Marine Mammals in the News

Estuaries are one of the most impacted habitats by human disturbance. Estuaries are also home to many unique species of marine life, and specifically, the estuaries of Germany and the Netherlands are home to the harbor porpoise. The harbor porpoise rotates periodically between the North Sea and these estuaries and are almost constantly hunting due to their energetic demands.

It just so happens that the estuaries these mammals frequent are utilized heavily by humans for transportation, tourism, shipping, etc. Little research has been done on how, when, and why harbor porpoises utilize estuaries. However, a study published in 2021 sought to do just that, with the goal of aiding estuary management.

Dr Thomas Taupp found that harbor porpoise presence was largely determined by the season, tide, and noise level, with the porpoises favoring low noise levels and the spring. The noise level was especially important due to the fact that harbor porpoises rely on echolocation to communicate and orient themselves. In fact, noise pollution is one of the largest threats to harbor porpoises, as it not only masks their communication but can also cause physical harm in extreme cases. Imagine you’re trying to order your dinner in the noisiest restaurant ever, or simply trying to speak to your friends! That’s how it is for these harbor porpoises operating within these estuaries.

The study suggests that the data collected pinpointing the times of the day/month/year that harbor porpoises are most active should be taken into account during daily operations within the estuaries. Seeing as harbor porpoises appear to be at their most active and abundant at night, this may be more feasible than it first seems!

Although harbor porpoises are not present in every estuary, and every estuary has its own individual problems, research like this should be looked at as an example of how science can go hand-in-hand with optimizing human actions, as well as highlight how human actions always affect nature in some manner and we should do so as mindfully as possible!

For more information, check out the original scientific paper:

Taupp, T. (2022). Against all odds: Harbor porpoises intensively use an anthropogenically modified estuary. Marine Mammal Science, 38( 1), 288– 303.

All families fight, it is just a fact of life. People have different opinions, ideas, and goals that tend to clash when groups are around each other too much. When your family is feuding, do you ever wish you could do something to ease the tension? Well, orcas have a solution! It is known as group splitting.

Like humans, orcas have a complex and deep-rooted social structure. They are one of the few animals on Earth whose offspring stay with their mother for life! Because of their matrilineal attachment, orca families can get quite large, thus, increased fighting is inevitable. To counter this, orcas practice a phenomenon called group splitting. This is when a single pod splits into two separate pods. While this term may have a negative connotation, do not fret, the two pods can still intermingle and communicate; having a smaller pod simply reduces stress for the family.

A study conducted from 1980-2010 observed the splitting habits of 16 pods in the eastern North Pacific. Group splitting, also known as fission, was hypothesized to occur for five reasons: 1) group size, 2) food availability, 3) reproductive conflict, 4) kindship, and 5) leadership experience. To clarify a few terms: reproductive conflict occurs when two (or more) pregnant or lactating females are in one group. These females must eat more to support their babies, and because of this, having more than one in a group is not optimal. Fission will occur to separate the costly females. Because orcas have a matrilineal society, pods are led by a female monarch; she is traditionally the oldest and wisest in the family. When a monarch dies there is usually a split to prevent a violent battle for leadership between the highest-ranking females. The final reason is when fission occurs without the death of a monarch. It is when two top females have equal ranking and knowledge; they will split and lead two separate pods to avoid internal conflict.

By the end of the study, only 4 of the original pods remained. The other 12 pods had split for one of the reasons above. Group size was determined to be the most prevalent reason for fission with food availability following as a close second.

Tough times are ahead for ocean dwellers, and orcas are no exception. Climate change is a present danger, and the effects grow with each passing day: food sources are disappearing, waters are warming, and tensions are rising. This study’s knowledge of group fission helps determine how orcas will be affected as their world changes. In the future, we may see smaller families of orcas, or even the abandonment of pods altogether. Only time will tell how orcas will adapt, and we must pray it is enough to ensure their survival.

For more information, check out the original scientific paper:

Stredulinsky, E. H., et al. (2021). Family feud: Permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca). Behavioral Ecology and Sociobiology, 75(3). https://doi.org/10.1007/s00265-021-02992

In the Western Pacific Ocean, the Pantropical Spotted Dolphin is at high risk of population decline from bycatch in commercial fishing nets. Bycatch is when a non-targeted species is unintentionally caught and entangled in a fishing net, which typically leads to the animal’s loss of life. Since the 1950s, oil and gas extraction industries, commercial fishing, and transportation have expanded. This expansion has resulted in increased threats to marine life, especially threats to the spotted dolphin from commercial fishing through bycatch. In a recently released study, researchers have developed a new system to decrease this threat to the dolphins. The researchers self-developed the Acoustic Deterrence System (ADS) to try to help decrease the number of dolphins that are being entangled in fishing nets. This system creates a noise at a frequency that only the dolphins can hear which causes them to change their actions, such as swimming away to get away from the noise.

Having an ecosystem with a diverse array of species is important to marine environments because all species allow the ecosystem to remain healthy and balanced. The research being done to reduce the number of spotted dolphins that are being killed is important because they play a major role in the balance of their marine ecosystem within the Western Pacific Ocean. There is an ecological phenomenon which describes how one species affects another and, in turn, affecting multiple other species, which can disturb an entire ecosystem. Pantropical spotted dolphins’ main food source small schooling fish, squid, and crustaceans. Thousands of these dolphins are being entangled and killed in the fishing nets that are meant for the dolphins’ food sources, causing a rapid decline in dolphin populations. This decline causes an increase in the dolphins’ prey populations which can have a negative effect on the ecosystem, such as harming the health of coral reefs.

The researchers found that within 20 minutes of the signal being on, all dolphins had swum away and were out of sight. The frequency caused the dolphins to avoid the fishing net without causing a change in the actions of the targeted fish species. Due to the positive effect that the ADS has on dolphin behavior, this system is one possible solution to the issue of dolphin bycatch. This system could be put into effect in all fisheries if the equipment were improved to be more easily operated by fishers and made less costly for the system to be expanded to users around the world. If fishing vessels employed this improved system on their nets, the number of dolphins that are entangled in their nets could dramatically decrease. This could immensely help to conserve and protect the pantropical spotted dolphin populations within the Western Pacific Ocean.

For more information, check out the original scientific paper:

Fu W, Song Z, Wang T, Gao Z, Li J, Zhang P and Zhang Y (2022) Acoustic deterrence to facilitate the conservation of pantropical spotted dolphins (Stenella attenuata) in the Western Pacific Ocean. Front. Mar. Sci. 9:1023860. doi: 10.3389/fmars.2022.1023860.

Recently in the area of Oaxaca, Mexico there has been an increased focus on two dolphin species due to an increased number of tourists visiting the area. Stenella attenuata, spotted dolphin, and Stenella longirostris, spinner dolphin, are the two species in the spotlight. This recent increase of interest about the two dolphin species has brought to light the question of whether or not there is foraging segregation between the two species of dolphin or if the two have similar feeding habits. In a study that took place of the coast of Oaxaca, Mexico in the south pacific from 2016- 2019 four observers took note of the various groups of dolphins in the area, and collected skin and blubber samples from which they were able to compare the isotopes in the samples to isotopes from samples of fish species collected from the local marketplace.

The researchers hypothesized that since the two species were in the same area there would be foraging segregation between them and that both species would have their own little niche if you will. This hypothesis did not however turn out to be the case and in fact when comparing the overall diets of Stenella attenuata and Stenella longirostris, the two species of dolphin seemed to have very similar diets with the most notable difference being that the Spinner dolphin diet consists of about 12.7% more Benthosema panamense, lanternfish, than the spotted dolphin diet but other than that the diets are quite similar. Although the two diets were quite similar other prey species that were not able to be found at the local market were not accounted for and therefore could play larger parts in the diets of these dolphins which unfortunately does leave some room for error in this experiment.

Overall while there is not as much foraging segregation as expected, the two dolphin species Stenella attenuata and Stenella longirostris do not seem to be competing for food resources and at the good old saying “there are plenty of fish in the sea” seems to reign true, at least for now.

For more information, check out the original scientific paper:

Enríquez‐García, A. B., Villegas‐Zurita, F., Tripp‐Valdez, A., Moreno‐Sánchez, X. G., Galván‐Magaña, F., & Elorriaga‐Verplancken, F. R. (2022). Foraging segregation between spotted (Stenella attenuata) and spinner (Stenella longirostris) dolphins in the Mexican South Pacific. Marine Mammal Science, 38(3), 1070–1087. https://doi.org/10.1111/mms.12912

Step (1) Slowly open the mouth as wide as possible with a large inhalation. Step (2) Keep the mouth open as wide as possible. Step (3) Quickly close the mouth with a large exhalation. After three simple steps, it is possible to complete a yawn. While these three steps may be routine for humans, this process of yawning has not been well documented across the animal kingdom. But recent data suggests that a second fully aquatic marine mammal will also respond to drowsiness in the same way that we do, with a simple yawn.

Dugong dugon or better known as a sea cow, is a species of fully aquatic marine mammals that are members of the order Sirenia. Following this study, the Dugongs are the second fully aquatic marine mammals species to exhibit yawn-like behavior similar to that of common bottlenose dolphins. The first instance of yawn-like behavior was seen by the female dugong “Serena” who lives at Toba Aquarium in Mie, Japan. This behavior was observed through a series of underwater cameras”for six days, between 7:50 am and 10:00 am, from October 2019 to July 2020.”

The yawn-like behavior was classified under the same conditions as the study conducted on common bottlenose dolphins eliminating potential misrepresentations of yawn-like behaviors. To define yawning, it was broken down into the three steps described earlier with additional requirements that Step 1 must last longer than Step 3. The researchers also calculated various swimming speeds to define a speed equivalent to that of resting state for the Dugong. After determining the requirements for classification of yawn-like behaviors and resting states, the researchers immediately began to record observations.

In terms of results, the researchers found 17 instances of open mouth behavior, and 14 of these behaviors were classified as yawn-like with the majority of these observations being found during a resting state. With these observations, the scientists found evidence to support their hypothesis that yawn-like behaviors would occur during resting periods similar to that of other marine mammals.

While these results of a yawning sea cow may seem insignificant, they provide great insight into the interconnectedness of mammals. Yawning is an often overlooked and simple behavior that is currently only known in a variety of mammals. By further expanding the list of mammals, this study illustrates the connections between various evolutionary lines that are objectively quite different. While it may be odd that yawning can illustrate such a large concept, it just further shows how interconnected all animals are.

For more information, check out the original scientific paper:

Enokizu, A. et al. (2021) Observation of Yawn-like Behavior in a Dugong (Dugong dugon). Journal of Ethology. 40:103–108. https://doi.org/https://link.springer.com/article/10.1007/s10164-021-00732-z#data-availability.

The need to find renewable energy sources is more important than ever before with the threat of climate change looming large on the horizon. Even with the advancements in wind and solar energy, the demand is still much too high to rely on those alone. To help lower the demand, a new marine energy industry looks to help solve this problem. Tidal turbines, much like their land counter part wind turbines, looks to harness the powerful energy behind the tides.

These turbines need to be in places with the largest and most powerful tides in places like the Bay of Fundy in Canada or Pentland Firth off the north coast of Scotland, where the largest tidal turbine array is currently located. This area is also home to a population of Harbor Seals (Phoca vitulina), a species in decline for the past twenty years for reasons such as entanglement in fishing gear and predation. The fear many scientists and other activists have is that since the turbines may be placed in areas with high seal or other mammal populations, strikes and other disruptions may occur.

In a first of its kind analysis of how marine mammals react with this new technology, researchers attached GPS tags to fourteen harbor seals. Their hope is to see when and where the seals are in relation to their haulout locations, where they typically go on land between eating cycles. With help from the operators of the turbines, they found behavior that was not expected yet promising for the future of this industry.

While there was no data that showed seals hitting the turbines, it did show something else. There was no observable difference in seal activity while the turbines were off. However, when the turbines were on, the seals stayed away from the area. Data showed that seals stayed at a minimum two kilometers (1.24 miles) away from the array, and there was an increase in seal activity at an island six kilometers (3.7 miles) away. This behavior is an avoidance response to the noise that the turbines create. These turbines operate at acoustic signals of 1 kHz (kilohertz) and 20 kHz, while seals are sensitive to noise between 0.1 kHz and 50 kHz.

This shows promise that the array, when operational, will deter seals and most likely other mammals from coming close to them, but this may cause other problems. If placed too close to haulout locations, breeding sites or other important locations for other mammals, these turbines can affect the animals in numerous ways. This is a first of its kind test and others to come may back up these findings or counter act them. While that may be the case, this form of energy making has a lot of room to grow, but we must be careful to protect these amazing species while we still have the chance.

For more information, check out the original scientific paper:

Onoufriou, J et al. (2021). Quantifying the effects of tidal turbine array operations on the distribution of marine mammals: Implications for collision risk. Renewable Energy. 180: 157-165. https://doi.org/10.1016/j.renene.2021.08.052.

Climate change is real and happening and most of the time when we think about climate change, we think about how it’s affecting ourselves or our earth, or the animal population as a whole. Rarely do we think about how it can specifically affect an individual population. In an article written this past year by scientists working in the Beaufort Sea, they studied how climate change will affect a population of beluga whales.

Beluga whales in the Beaufort Sea migrate throughout the year in order to mate, as well as feed themselves and their babies. The scientists in this study used transects, observations, aerial views, and discussions with other scientists to gather their data. They found that Belugas migrate from the Beaufort Sea in the winter to the Bering and Chukchi Seas in the summer. The scientists also found that Belugas chose their location based on multiple factors, but primarily the temperature and the amount of suspended particulate matter. Belugas prefer warmer waters and more turbid waters. They also chose their location primarily near the mouth of the Mackenzie estuary, located in the Beaufort Sea.

Global warming and climate change can drastically change the preferred ratio of these conditions for the Beluga whales, causing them to migrate elsewhere. Climate change can have a drastic effect on water temperatures, coastal erosions, and turbid waters. Beluga whales migrate to certain areas in the summer because of these exact conditions and climate change could make them have to relocate completely. Many efforts have been made to try and help figure out what to do with these animals as well as others when the time comes for them to have to relocate. The best thing we can do is to continue our efforts to try and slow down climate change and help figure out places for these animals to go that won’t cause too much stress and duress on them.

For more information, check out the original scientific paper:

Noel , A. N., et al. (2022). Environmental drivers of Beluga Whale Distribution in a changing climate: A case study of summering aggregations in the Mackenzie Estuary and Tarium Niryutait Marine Protected Area. Arctic Science. 8(4): 1305-1319. https://doi.org/10.1139/as-2022-0003

The on-going COVID-19 pandemic has had an immense effect on us all globally. But as the panic subsides and we find new ways to combat it, there is now another set of individuals the virus could begin pursuing: marine mammals! In recent studies, scientists are testing the potential of marine mammals’ susceptibility to encountering the COVID-19 virus. As concern over how the virus could be spread through wastewater grows, there has been a newfound look into whether marine mammals could pick up COVID-19. Wastewater has become an important factor in considering response to COVID-19. Through our own tests, we have found that infection can spread to several body systems, including the gut.

Wastewater sources entering natural water systems is an important example of how many ecosystems become interconnected. Wastewater typically goes through one, two or three stages of treatment. The first sorting out any solid waste, the second breaking down and filtering dissolved bio-material, and finally if a third treatment is used the water undergoes further processes to reduce nutrient and pathogen content. Studies have shown a decrease in levels of viral load with increasing levels of treatment of wastewater.

Now, conversation around the impacts that humans have on animals is not a novel subject, yet there is so much we can still learn. Animals such as the sperm whale, and sea otters which are quite coastal, are some of the most susceptible to COVID-19 risks. The case study looked into animals across many ecosystems and compared data of their locality to wastewater sites, their status on the IUCN red list (whether they are considered vulnerable, threatened or endangered) and how susceptible they could be based on known genetic information. The risks extend to far beyond just the animals in the study. Imagine these social creatures, who have no way of knowing if they are susceptible and become infected, could spread the virus to animals we are unaware of being susceptible as well. When many of the marine mammals discussed are considered threatened or endangered, this could pose a serious threat to vast numbers of populations.

While the whales, seals and otters have no way to prevent themselves from potential exposure – I sure wouldn’t recommend single-use masks to our marine mammal friends – there are many steps we can continue to take to fight this relentless virus. Diving deeper into the process of wastewater treatment, and improving these systems, is a great first step. As well as continuing to study effects of these and other human-to-animal viruses to mitigate any future risks. The more we know about our natural systems, the more we can maintain a healthy balance.

For more information, check out the original scientific paper:

Sabateeshan, M. et al. (2021) Pandemic Danger to the Deep: The Risk of Marine Mammals Contracting SARS-COV-2 from Wastewater. Science of The Total Environment. 760:143346. https://doi.org/10.1016/j.scitotenv.2020.143346.

What do you think of when someone says raking? Autumn leaves being swept into piles, perhaps with the intention of jumping in, or maybe just as a mildly annoying chore? While this may be the case for many of us, the term ‘raking’ has an entirely different meaning when it comes to killer whales. In their world, rake marks are thin lines seen on a whale’s skin as a result of other whales dragging their teeth across it during aggressive, and sometimes playful, behavior.

But killer whales are far from the only animal to show aggressive behavior to their own kind; in fact, most animals show aggression to members of their own species when resources, such as food, are scarce, so is this what’s going on with the killer whales? Take the Southern Resident Killer Whales for example. This is an iconic population off the coast of Washington and British Columbia that feeds primarily off the chinook salmon. However, when comparing rake marks from the Southern Residents with fluctuations in their prey source -the chinook salmon, scientists found a curious pattern. Unlike what the behavior of other animals suggested, the killer whales had fewer rake marks when food was low, even after additional factor such as age and sex were accounted for.

At first glance, this makes no sense, aggression to compete for limited food would clearly help the individual whales not starve. However, these interactions take a lot of energy, so in times of low food, they may not be worth the cost. Imagine how exhausting it must be to get into a fight if you’re already beginning to starve. Raking can also be attributed to play in certain circumstances, which is a behavior that is reduced during periods of low food. Finally, killer whales tend to split into smaller groups during these times, so the chances of two individuals interacting go down.

What this shows us is that raking, a behavior phenomenon which demonstrates complex social structure and hierarchy, is disturbed by changing food abundance. The chinook salmon, which they eat, are an endangered and actively declining population. We know that food shortages can have massive and devastating social ramifications on human populations, but what about other socially intelligent animals like the orca?

For more information, check out the original scientific paper:

Grimes, C et al. (2022) The effect of age, sex, and resource abundance on patterns of rake markings in resident killer whales (Orcinus orca). Marine Mammal Science. 38:941-958.

When you buy a can of tuna at the store, have you ever wondered why it says, “Dolphin Safe?” Why would dolphins be hurt when making cans of tuna? Well, in 1972 the United States enacted the Marine Mammal Protection Act, or MMPA, to protect the whales, dolphins, and other marine mammals we all love.

Part of the act is to minimize marine mammals caught by accident when fishing for other things, like tuna. So, while dolphin won’t be found in your tuna can, its possible that more than a couple may have died trying to get it. While the MMPA is only effective in America, countries and fisheries all over the world are partaking in similar acts to protect their own marine mammals.

Recently, a fishery in Peru has started implementing a new device which may lower dolphin by-catch; “pingers” were attached to fishing gear that would emit a high frequency ping meant to deter dolphins and other small marine mammals. You might remember that dolphins use echolocation to hunt food and thus are sensitive to high frequencies, and that’s exactly the thought behind these pingers. By making a high-pitched noise the dolphins will hear it and know to stay away.

Over the course of 16 months and over 300 fishing trips these pingers managed to show a reduced bycatch of small marine mammals by 83.3%! With such an amazing decrease in bycatch, its incredible to know that the ability to catch fish was not affected. It seems like a great leap in protecting our marine mammals, but there was one major downside to the observation.

Humpback whales were found to not be affected by the pingers. In the 16-month observation, 16 humpback whales became entangled by the fishing gear. However, this number is not necessarily larger than before and thus is not harming more whales. Since reducing bycatch of common dolphins and pilot whales (a close relative of the dolphin) was the main purpose of the pingers, this observation shows great success and a potential for safer fishing in the future.

Although we have a long way to go in the protection of marine mammals, fisheries in Peru have taken a big step in reducing the bycatch of marine mammals. Hopefully many fisheries in the future will continue finding innovative ways of protecting these species and continuing to put our best fin forward.

For more information, check out the original scientific paper:

Guidino, C. et al. (2022) Pingers Reduce Small Cetacean Bycatch in a Peruvian Small-Scale Driftnet Fishery, but Humpback Whale (Megaptera novaeangliae) Interactions Abound. Aquatic Mammals. 48(2).

Franciscana dolphins, also known locally as La Plata, are a species of small river dolphins distributed along the southeastern coast of Southern America. Rather than residing strictly in freshwater rivers, these dolphins may also inhabit murky, shallow ocean water that reaches depths of 6-25 meters and feed on a variety of prey sources, including benthic organisms, squid, and fish. However, due to these foraging strategies, these species are currently experiencing extreme population declines due to fishing industries.

As of 2017, the Franciscana dolphin was listed as vulnerable on the IUCN List of Threatened species due to a lack of sufficient data on population sizes. However, the Brazilian government has moved the Franciscana from “vulnerable” to “critically endangered” in their national list of endangered species. The primary cause for this species’ decline is due primarily to bycatch by gill nets. These nets are a type of gear that have vertical nets suspended within the water column which soak for multiple hours to a whole day. Due to the nature of these nets, the sheer amount of space they take, and the hours left unattended, are an extreme risk to many marine mammals, especially when the nets are intended to catch the animal’s prey sources.

One solution to avoiding any bycatch of these dolphins could be avoided by using pingers – small sound sources that produce specific frequencies to notify cetaceans about the presence of the nets. However, fishermen refuse to use them because of their “dinner bell” effect on pinniped species. Pinnipeds eventually associated the sound with easily accessible fish and would either damage the fishing gear or be more likely to tangle themselves in the gear as well. In 2021, Renan and his crew decided to experiment and test the effectiveness of a new type of pinger in Babitonga Bay in Southern Brazil. Called the “banana pinger,” this device is to emit frequencies lower than pinnipeds are able to hear. With most pinniped hearing sensitivity extending to 20 kHz and 40 kHz, sensitivity is thought to drop sharply above these values. So, with the banana pinger, the hope is to be able to deter the Franciscana dolphins away from the net without attracting any pinnipeds toward the gear.

Within their 65 days of experimenting, the results were positive! The presence of Franciscan dolphins next to the pinger and within 100m of the pinger decreased by 19.4% and 15.4% respectively, indicating that they were avoiding the pinger. However, this avoidance response could not be observed at 400m, meaning that the sound was lost somewhere in between. With modification and further studies, these pingers can be improved.

After their experiment, Renan and his peers suspect that accumulated data could result from seasonality and many other factors, but there is effectiveness. They encourage others to further study and look into the use of pingers adjacent to seasonality and different populations to establish better conservation efforts. However, action needs to be taken urgently. Even if shortterm, bycatch needs to be reduced to give the Franciscana dolphins a chance.

For more information, check out the original scientific paper:

Paitach, R. L., et al. (2022). Assessing effectiveness and side effects of likely “seal safe” pinger sounds to ward off endangered Franciscana dolphins (Pontoporia blainvillei). Marine Mammal Science, 38(3), 1007– 1021. https://doi.org/10.1111/mms.12907

Many people worldwide say we are now in a post-whaling world, but in reality we are all whalers. Even if you aren’t a whaler for a living, people are contaminating the ocean with hazardous toxins and killing whales without knowing. There has been a recently identified issue with the Eastern Caribbean and the over extraction of odontocetes, which are toothed whales, such as a killer whale or dolphin. This takes place in St. Vincent and the Grenadines (SVG), these whaling operations are harming the whales and the populations that consume Odontocetes.

In modern whaling times, challenges are arising within the industry. There are shifting cultures and dietary preferences that could lead to a decline in Odontocete populations in response to over extraction. The whaling industry is not only affecting whale populations, but people too because of toxins that have bio accumulated within the whale tissues people consume. Bioaccumulation is when toxic substances build up in an organism’s fatty tissues so fast that they cannot excrete the toxins out as quickly as they are being built up. The two main focuses of this whaling issue in SVG are understanding the consumption patterns and demands for Odontocete-based food and how this affects the whale population. The other focus is understanding how Mercury and other environmental contaminants are being consumed by humans. This may pose a major threat to human health, especially in regards to children’s neurological development. It was found that the whales they had harvested had alarmingly high rates of mercury in their tissues that had grown higher in levels due to bioaccumulation.

One issue that makes it difficult to study the whaling community in SVG is the records being kept by the whaling industry are unreliable because they don’t keep track of the numbers or they are dishonestly logging the whaling numbers. This is difficult because without having exact records it’s difficult to study the correlation between how many whales are being consumed and how many are being harvested. Now researchers are trying to propose ideas that can help keep whale populations high and also keep humans safe from consuming the toxic tissues in whales. One suggestion was to study how mercury is making its way into the ocean and what the route source is. If they understood the pathway mercury is coming from it will greatly help to reduce the amount of toxins coming into the ocean. Another recommendation was to accurately predict the populations of odontocetes and how whaling impacts their well being. They also suggest putting catch limits in place to preserve populations, but also humans would consume less toxic whale meat if they are not bringing in a surplus of whale catch. Other contributors to the decline in Odontocete populations is not only whaling, but ship-strikes, fishing gear entanglement, noise pollution, and anthropogenic pollutants. It’s unsure if progress will be made within the whaling industry, but one can only hope people smarten up before they too harm themselves with hazardous toxins from consumption of odontocetes.

For more information, check out the original scientific paper:

Fielding, R. (2022) Whalers in “A Post-Whaling World”: Sustainable Conservation of Marine Mammals and Sustainable Development of Whaling Communities—With a Case Study from the Eastern Caribbean.Sustainability, 14, 8782. https://doi.org/10.3390/su14148782

Summary: How is a warming world impacting marine mammals in arctic ecosystems? This study looked at the isotopic niches of ten marine mammals to analyze which species are most at risk in their warming environments. Skin and blubber samples were taken to identify lipid sources from their diets and their place in the arctic food web, in order to paint a better picture of their specific niches.

For more information, check out the original scientific paper:

MacKenzie, KM et al. (2022) Niches of marine mammals in the European Arctic. Ecological Indicators, 136: 108661. https://doi.org/10.1016/j.ecolind.2022.108661

In Peru, fishermen layout labyrinths of gillnets in coastal waters, attempting to catch rays, sharks, tuna, and other large game fish. These nets are constructed to capture target species similar in size to some local marine mammal species such as dusky, bottlenose, and common dolphins, as well as Burmeister’s porpoise. These mammals have found themselves under increasing pressure from bycatch, with landing by gill net fisheries reaching 20,000 individuals between 1990 and 1994. Despite a commercial ban on the capture of marine mammals in Peru, these gillnet interactions increase continuously, as local populations and demand grow. Another species often caught in these nets are Humpback whales. These whales, while larger than any target species designed for, often become tangled in the several hundred meter long stretches of netting.

Net removal practices have allowed some individuals to escape from entanglement, however, drownings still occur. An alternative solution to simply responding to the damages caused by these nets is the implementation of sonar pingers to act as active deterrents to marine mammal interactions. These pingers work by sending out short low intensity sounds, usually between 10 and 140khz, informing the marine mammals in the area of the net’s presence. Despite the positive results observed in interactions with small cetaceans, decreasing entanglement by 83%, Humpback whale interactions with these pinger-equipped nets remained high, with no statistically significant decrease observed. This is believed to be a result of the different frequencies typically heard by these different species. Pingers used for small cetacean species use a higher frequency noise, which may be imperceptible to Humpback whales, which typically send and receive calls in the 15hz to 3khz range. The implementation of acoustic pingers in a range heard by both species, possibly 8-12khz, or the inclusion of pingers specifically meant for the deterrence of humpback whales, could prove beneficial to recovering populations in Peruvian waters.

In addition to the reduction in bycatch of marine mammals, the capture rate of targeted species was relatively unharmed. Catch rates of fish species such as tuna rays were statistically unaffected. A 32.9% reduction in shark capture was observed, but alterations in frequency or use case of pingers, or economic incentives could mitigate this issue. Despite this promise, further research needs to be done to prove the viability, and test the ideal frequencies used for this conservation strategy.

For more information, check out the original scientific paper:

Guidino, C. et al. (2022) Pingers Reduce Small Cetacean Bycatch in a Peruvian Small-Scale Driftnet Fishery, but Humpback Whale (Megaptera novaeangliae) Interactions Abound. Aquatic Mammals. 48(2).

Researchers have long been perplexed by the phenomenon of the decrease in Blue Whale song frequencies since they observed it in the past few decades. Frank Malige and a team of researchers take a new approach to the question by incorporating mathematically derived models to attempt to see how different environmental or social pressures have on the decreasing frequencies that have been observed.

First the researchers looked at how a group of whales social interactions affect the song frequency. When they compared factors such as competition and conformity, they found that a higher competition level with a lower desire for conformity resulted in the most frequency drop, whereas a low competition level and high desire for conformity resulted in the lowest rate of frequency drop.

Next the researchers looked at how newborn calves in a group adapted to sing at the same levels of the group. They found that when new calves were born into the population, they almost instantly began to sing at the frequency levels currently being sung by the group of whales and continued to follow the drop in frequency for the rest of their lives. As more generations of calves were born, they would start out singing at lower frequencies than calves in the previous generation. This was because the male whales who could sing at the lowest frequency being the most desirable to females, and those male whales then passed the lower frequency trait to their young.

The researchers determined with this data that the most plausible reason for the drop in frequency was due to competition for females. The concluded that the female whales were more likely to breed with the lowest frequency males as it made them stand apart from the rest of the group. This study is one of the first that concluded that a possible reasons for the decreasing frequency observed in the whale songs was because of competition for females on breeding grounds.

For more information, check out the original scientific paper:

Malige, Frank et al. (2022) Mathematical models of long term evolution of blue whale song types’ frequencies. Journal of Theoretical Biology, 548:111184

Nowhere else in the world will you see an entire seal population exist so closely to humans as Lake Saimaa in Finland. The Saimaa ringed seal is a subspecies of the ringed seal with relatives the Baltic Sea and Lake Ladoga. This particular charismatic subspecies has been faced with an unfortunate dilemma; gaining a spot on the IUCN Red list, the equivalent of America’s endangered species list, due to years of overexploitation.

Though it’s hypothesized that the Saimaa ringed seal has been known and exploited for about 6,000 years through finding archeological evidence of their remains in hearths, they were first described in the late 19th century. Upon being discovered, they were immediately believed to be competition to the fisheries on Lake Saimaa. Bounties were placed on this seal subspecies, and continued to be in place for nearly 50 years until the population was so diminished that it caused local extinctions in certain parts of the lake.

Since then, conservation measures have been taken to ensure their survival. These methods include fishing gear regulation, protected areas, ban on hunting, awareness campaigns, and improved knowledge on seal-safe fishing methods. Due to these efforts, the Saimaa ringed seal managed to narrowly escape extinction in the 1980s and increase their numbers to the approximate 400 individuals that we see today.

While this recovery is incredible and leaves a highly optimistic feeling for the future of these seals, they are not out of the woods yet. They still face a number of challenges that keep them from being removed from the endangered species list. Some of these challenges include recreational fishing, climate change, pollution, human disturbance and habitat loss, fluctuations on lake water level, and stochastic effects of inbreeding.

Though these challenges seem daunting, Finland is rising to the occasion. To combat the dangers of recreational fishing, fish-baited hooks, certain fish traps, strong-mesh gillnets, multifilament nets, and trammel nets have all been banned from use in Lake Saimaa. There is also an annual ban on gillnetting in place from April 15th until June 30th. To combat increased pup mortality due to climate change, the people of Finland have begun creating makeshift breeding lairs and artificial nests that have helped to improve the survival of these seal pups.

The Saimaa ringed seal has experienced some tough times, and continues to face many new potential challenges as climate change continues to alter their habitat. However, they have proven to be quite the resilient subspecies and continue to pull themselves through. So long as Finland continues to mitigate human disturbance of these seals, they certainly have a fighting chance at long term survival.

For more information, check out the original scientific paper:

Kunnasranta, M., et al. (2021). Sealed in a lake – biology and conservation of the endangered Saimaa Ringed Seal: A Review. Biological Conservation. 253:108908. https://doi.org/10.1016/j.biocon.2020.108908

In the past few decades, the changing climate has demonstrated its potential to critically alter marine mammal growth and morphology. This trend has been studied in regard to anthropogenic anomalies along with naturally reoccurring events like El Niño and Antarctic Oscillation and has been of special interest to the researchers at the Center for the Study of Marine Systems (CESIMAR) in Argentina. South American sea lions are known to have a significant presence in the Argentine Sea and exhibit a very generalized diet, which can vary depending on prey availability and abundance. The diet of these pinnipeds is not only important for body growth and reproduction, but tooth development is also dependent on the vitamins and minerals they intake. With climate anomalies expected to increase, the researchers at CESIMAR set out to study how these events might affect the dental development of the sea lions.

Upper canines were collected from ninety-six South American sea lions that had stranded or been captured by fisheries as bycatch along the eastern coast of Argentina. Researchers focused on sexually mature individuals, which were considered as females older than six years of age and males older than four years. Tooth sections were then examined under a stereo-microscope using a method similar to dendrochronology to count and measure consecutive layers of light and dark dentine growth.

Across the series for female sea lions, when Antarctic Oscillation (SAM) was in a positive phase the growth index measured was greatly reduced in comparison to periods of negative phases. Conversely, there was no significant growth trend noted for males. Females appear to be more sensitive to environmental variances, likely influenced by having smaller home ranges than male sea lions and often being restricted by their pups. Shallow dives for food are directly affected by increased surface water temperatures and decreased upwelling, which are characteristic of Antarctic Oscillation. While these anomalies can be short-lived, these findings may pose another concern to researchers of climate change, an environmental “anomaly” that is not likely to be short-lived and displays increasingly negative effects over time.

This study bears significant implications for the future of South American sea lions and likely other marine mammals. With climate anomalies like El Niño and Antarctic Oscillation expected to increase and ocean temperatures continuing to rise, the composition and phenology of our primary producers, as well as primary productivity, are anticipated to feel an impact. The relocation of primary food sources to colder regions would be expected to have bottom-up effects and eventually lead to decreasing sea lion populations, that is if these predators are unable to gain the necessary nutrients for proper growth from an alternative source. This effect could be particularly detrimental to female sea lions and their young, who are known to hunt in shallower waters and prioritize the safety of their pups over the advantages of a larger home range that males can more easily embrace. Further research is required and greatly encouraged to gain a better understanding of how these climate events may affect sea lion populations, how the public might respond to support the populations most influenced, and how to avoid an ecological crisis due to climate change.

For more information, check out the original scientific paper:

Heredia, Federico M. et al. (2021) Climate anomalies influence tooth growth patterns of South American sea lions. Marine Mammal Science 38: 175-189.

Three thousand meters. In our oceans it is an unfathomable depth, and some might believe unfit for life. Not for Cuvier’s Beaked Whale. This marine mammal can dive to unthinkable depths to look for food. As other whales, they use echolocation, reflecting sounds off objects to locate them, and these sounds may allow for something else.

Scientists have been taking advantage of this. As image counts can’t create an actual picture for how many of this species there are because they only spend two minutes at a time on the surface, scientists have decided to use audio and acoustic technology to determine the whale’s locations. As all whales, they create a distinct sound at an identifiable frequency, and it is detectable up to four kilometers. This is over the maximum depth they reach which allows for reassurance in the numbers found.

Researchers placed 22 microphones specifically designed and programmed to capture these sound frequencies across the coast of California, a known location of these whales. They then, with third parties, set strict standards amongst the factors that would count as a Cuvier’s Beaked Whale sound. As they travel in groups, they determined findings with an assumed group size based on previous data. This resulted in finding over a thousand potential discoveries of individual whales and determined to be just about over 800. This is over 50% greater than found before meaning these whales are quite abundant in just this part of the world alone!

As they live in many of our world’s oceans, there are likely to be many more out there than we previously expected. However, the truth may never be known, as despite these findings, they were still heavily dependent on previous observational data that came before it. As this technology develops, with other species that use echolocation, be it dolphins or other species of whale, we may be able to find more accurate numbers of population size. This can lead to confidence in species stability or endangered status allowing governments of the world to allocate resources appropriately.

For more information, check out the original scientific paper:

Barlow, J., Moore, J. E., McCullough, J. L., & Griffiths, E. T. (2021). Acoustic‐based estimates of Cuvier’s beaked whale (Ziphius cavirostris) density and abundance along the U.S. West Coast from drifting hydrophone recorders. Marine Mammal Science, 38(2), 517–538. https://doi.org/10.1111/mms.12872

A paper published in the Aquatic Mammals Journal earlier this year has brought attention to the plight of California Sea Lions off the coast of Baja California, Mexico. More specifically, how 447 of the beloved animals ended up dead in the span of just three months during the summer of 2020. The proposed cause of this mass die-off could come as a surprise. The report found that a large bloom (sudden growth) of phytoplankton occurred in the area the sea lions were found, shortly before they were discovered dead. This piqued the interest of the scientists conducting the study. In previous years several other Sea Lion mass deaths were recorded off of California, USA. These events were linked to poisoning caused by toxic phytoplankton. The scientist were then faced with a question; could the same thing be happening in Mexico? Unfortunately no conclusive evidence of poisoning by toxin was available. At the time of the dieoff in 2020, no phytoplankton samples were taken. It was impossible to confirm if the plankton bloom that occurred that summer was toxic or not. However, several pieces of circumstantial evidence support the theory that a harmful algal bloom (HAB) could be responsible for the deaths. Local reports noted that the dead seals appeared to have no wounds or evidence of interactions with fishing gear and boats that could have resulted in death. The reports also recorded a level of decay similar to decay seen in other Sea Lions known to have been poisoned by toxic algae. This evidence, along with with plankton bloom reported in 2020, has led the authors of the paper to conclude that it is highly likely that a HAB was responsible for the deaths of hundreds of California Sea Lions. The scientists conducting the study highlighted the need for further monitoring of California Sea Lions in Mexico and plankton blooms, which are expected to occur more frequently due to global warming. As unlikely as it seems, an organism invisible to the naked eye has the potential to do untold harm to an already struggling species, and with rising sea temperatures, this is not an issue that will be resolved anytime soon.

For more information, check out the original scientific paper:

Elorriaga-Verplancken, FR., et al. (2022) Largest Mortality Event to Date of California Sea Lions in Mexico Might Be Linked to a Harmful Algal Bloom. Aquatic Mammals, 48(1): 59-67. https://doi.org/10.1578/AM.48.1.2022.59

The lives of our beloved bottlenose dolphins may be at risk if a land restoration project in the Barataria Bay is acted upon. Barataria Bay is located in Louisiana and is part of the Gulf of Mexico. The land restoration project (Mid-Barataria Sediment Diversion Project), involves building and operating a channel that would deliver seasonally changing amounts of freshwater, sediment, and nutrients in order to restore a marsh and reduce land loss. If acted upon, the project will not be completed until 2070 (almost 50 years form now!)

This project was proposed in response to the catastrophic Deep Water Horizon oil spill. This involved an oil drilling rig stationed in the gulf of mexico. The rig exploded and sank into the ocean, leaking 134 million gallons of oil into the sea. This oil damaged marsh land along the coast of Louisiana and other territories around the Gulf of Mexico.

The issue with this proposal is that the amount of freshwater coming into the bay would drastically affect the bottlenose dolphins which are native to the area. Studies show that long exposure to low salinity levels will cause skin lesions and other diseases for these dolphins that will oftentimes result in death.

Studies that were run on the risk of completing the project show that more than a decade after, dolphins of the area will be functionally extinct.

Is this morally right? Should we risk the lives and homes of these harmless creatures in order to prevent land loss? Completing this project will take years to complete, almost fifty to be exact,  as it takes a long time for sediment to be transported enough to rebuild land.

The project may be aimed around environmentally conscious in the sense of restoring a marsh habitat, but destroying the way of life of a magnificent creature is inhumane.

It doesn’t take an activist to see the issue with a project like this. As of now the project has yet to be completed. We can only hope the lives of the bottlenose dolphins are considered when making the final decision.

For more information, check out the original scientific paper:

Thomas, L., et al. (2022). Model predicts catastrophic decline of common bottlenose dolphin (Tursiops truncatus) population under proposed land restoration project in Barataria Bay, Louisiana, USA. Marine Mammal Science,1-11.

The quiet, reserved African manatee is a secretive animal that lives along the west African coastline spanning from Senegal to Angola and the Senegal River. Overall, not much is known about this animal due to its remote habitat. In the Senegal River, there are lots of dams used for agriculture and hydropower. These dams have affected the manatee’s ability to move within the river and between the river and coast. They have been known to isolate manatee populations, for example, the Diama dam in St. Louis, Senegal blocked off the manatee’s channel between the sea and the river.

Scientist Lucy W. Keith-Diagne and her colleagues have an ongoing research project studying all aspects of the African manatee which included observing their migratory patterns in the Senegal River in 2009 and published their findings in 2021. The scientists’ goals were to understand how the dams in the Senegal River affect the navigation of the manatees and how they use their habitat. The scientists freed five manatees that were stuck behind a dam near Matam, a city in the northeast region of Senegal. They assessed the health of the manatees and put a special floating radio tag on their tail fin on three of the manatees. This way, the scientists could track the manatee’s movements. There were two male manatees that both migrated northwest in the river and remained in the same area. They were both tracked for 86 days until they lost their tags. The one female manatee was tracked for 325 days, migrating up and down the river more than the male manatees. The scientists concluded that the tracked manatees used over 308 kilometers or 191 miles of the river.

The scientists believe that the manatees migrated in search of food as they moved from areas with low vegetation to high vegetation. In general, the Senegal River is a habitat with low vegetation requiring the manatees to migrate often, as seen with the female manatee. While this study provided valuable information about the whereabouts of the mysterious African manatee, it also helped raise awareness of the issue of manatee isolation and entrapment behind dams.

For more information, check out the original scientific paper:

Keith-Diagne, LW., et al. (2021). First Satellite Tracking of the African Manatee (Trichechus senegalensis) and Movement Patterns in the Senegal River. Aquatic Mammals, 47:21–29.

Everything in nature is connected, and something that affects one piece of it likely has an effect on some other part. The relationships that exist between different species in the wild are intricate and often the topic of intense research and study. Some researchers from California recently uncovered the subtle relationship between a large species of starfish and one of the most charismatic and adorable mammals in the state: the sea otter.

You’re probably wondering what in the world starfish have to do with sea otters. Some researchers from California wanted to study this exact relationship, and to start, they began counting starfish.

Starfish are interesting predators. Feeding upon shellfish, they expel their stomachs from their mouths to digest their prey outside of their bodies. Their prey is then just slurped up and the full stomach returns to the starfish’s body. Some species of starfish feed primarily upon sea urchins. So when a lethal starfish disease rocked the coast of California, the sea urchin population skyrocketed. With one of their main predators almost eradicated due to the disease, sea urchins boomed so prolifically that some areas under the sea became devoid of kelp as the urchins ate it all. This is where the sea otters came in.

Aside from starfish, the other main predators of sea urchins in California are sea otters (the Internet is full of pictures and videos of otters cracking the shellfish apart with rocks as they drift on the surface of the ocean on their backs). Some scientists revealed an interesting phenomenon that all began when the starfish disease hit California. The starfish population decreased, so the sea urchin population increased, then causing the sea otter population to increase. Researchers began observing more and more individuals in the wild. Otters and starfish, two sea creatures that are about as different as can be, actually exist in a harmony that is thrown off-balance when the natural state of one is altered. This goes to show how the environment is like a well-oiled machine. When one part is removed, it can have cascading effects on other parts, and the entire machine could even break down. Conservation efforts cannot be concentrated on the species that people think are cute, like sea otters. The urchins and starfish must be conserved too for the well-being of the entire ecosystem.

For more information, check out the original scientific paper:

Smith, JG. et al. (2021) Behavioral responses across a mosaic of ecosystem states restructure a sea otter–urchin trophic cascade. PNAS 118: 11.

A blue whale swims underneath your boat as you cruise through the ocean. Before you know it, a calf appears next to its mother, an amazing sighting for any marine mammal lover. But then, another young calf appears: twins. This occurrence is extremely rare amongst cetaceans, which are made up of mysticetes (baleen whales) and odontocetes (toothed whales), as well as dolphins and porpoises and are typically associated with single offspring pregnancies. However, up until now, few studies have been conducted regarding cetacean multiplets and most have involved examining fetal data obtained during whaling, rather than the observance of live twins.

One study aimed to investigate how often these twin pregnancies actually occur amongst a variety of cetaceans, including but not limited to, humpback whales, sperm whales, Antarctic minke whales, and common minke whales. Researchers R.W. Drinkwater and T.A. Branch estimated the proportion of twins that were identical and fraternal, while also estimating the probability of survival of the duos. This data could then be used to predict future population growth.

The backgrounds of each individual cetacean species vary and with this variation, comes differences in reproduction strategies. For example, most odontocetes demonstrate social schooling during mating, while mysticetes usually are more monogamous in their mating patterns. Despite these differences, one factor remains the same regarding reproduction amongst all cetaceans: the birth of a single offspring per pregnancy. Most sightings of cetaceans accompanied by more than one calf are likely cases of alloparenting (adoption or assistance by unrelated individuals), but it could very well be a case of live twin birth.

In the study conducted by Drinkwater and Branch, pregnancy data for captured females was taken from the International Whaling Commission’s 1908–2020 whaling database. Using this data, it was found that 0.87% (2,197 out of 252,651) of pregnancies included multiple fetuses, including 12 instances of five or more fetuses in five different species, all baleen whales. For six species, the proportion of twins that are identical was estimated using Weinberg’s differential rule. Identical twins were also found to be less common than fraternal twins in all species (4%–34%), except humpback whales (57%). In order to investigate twin survival rates, researchers fitted models to the proportion of twins by fetal length, finding that the probability of surviving twins declined to almost zero with increasing fetal length for sei, fin, and blue whales; but not for sperm, humpback, and Antarctic minke whales. Because some fetuses may be missed at smaller lengths, they repeated this analysis excluding fetuses shorter than 2 ft (61 cm), finding that twin survival declined with increasing fetal length for sei, fin, blue, and Antarctic minke whales.

Few multiple pregnancies (<1 in 500) actually end in live birth, and even these pregnancies experience high mortality after birth. Successful birth of multiplets in large whales is exceedingly rare, indicating that births can be assumed to be single. This data can then be used in predicting future population growth amongst cetaceans.

For more information, check out the original scientific paper:

Drinkwater, R.W. & Branch, T.A. (2022) Estimating proportions of identical twins and twin survival rates in cetaceans using fetal data. Marine Mammal Science. https://doi.org/10.1111/mms.12929.

Scientist recorded a sperm whale travelling from the Canadian Arctic to Bermuda. This information was recorded in an experiment that took place in September of 2018 and October of 2019. A male sperm whale traveled 5,556 kilometers between the Canadian Arctic to the western North Atlantic, north of Bermuda. This is the longest documented satellite track movements for sperm whales.  This is a huge breakthrough for this species since there is limited information about sperm whale movement ecology.

The funny part is that this result was not even planned. Even the scientists were shocked that this happened. The scientists were only planning to use satellite linked tags on three male sperm whales in the Canadian Arctic in an restricted fishing area. The original experiment was to tag sperm whales with satellite link trackers that would transmit their position every six hours and to see how long the transmitters will work. Scientists were just testing out this new technology for satellite tracking on whales, since this would be the first time using this type of technology on this species. They just wanted to get a sense of what type of information could they get from using satellite tracking technology. The other two whales stayed within the restricted area and their tags lasted 9 and 11 days

However, the third whale slipped away from the restricted area and started to swim southward heading towards the lower Atlantic. The tracking system which was placed in the whale’s skin started to transmit results to a satellite after being quiet for hours that the whale is migrating out of the Canadian Artic and heading South. The tracking system stayed on the whale for 13 days and during this time the whale migrated 5,556 kilometers.  The transmitter went silent again and the scientists realized that it must have broken off. Scientists do believe that this was not the end of the whale’s journey, and they assume the whale continued southward possibly to the Gulf of Mexico or the Caribbean Sea which are breeding grounds for sperm whales.

Although this does not answer many questions like the most important one, which is where was the whale going to? It does provide insight into movement ecology especially for male sperm whales, where scientists are still questioning their movements from low latitudes to high latitudes. This is still a great breakthrough whether on purpose or accidental for the science community.

For more information, check out the original scientific paper:

Lefort, K et al. (2022) Satellite‐tracked sperm whale migrates from the Canadian arctic to the subtropical western North Atlantic. Marine Mammal Science, 38(3): 1242-1248

Scientists have used stranding events to their advantage in a quest to detect and document haplotypes of long finned pilot whales. The term haplotype refers to genes within an organism that are inherited together. Scientists have used these haplotypes to further scientific knowledge on the social structure and regional variation of long finned pilot whales in the Eastern North Atlantic and adjacent waters. From previous studies we know that long-finned pilot whales have complex social bonds, that take form in matrilines in small stable units. A matriline describes a social structure traced through the descendants of a female family line. From these units’ pods form, and larger social bonds come into play when pods interact with other pods.

The social interactions are critical to understanding stranding events. The objective of this study was to explore the social structure of pods involved in mass stranding events, assess maternal population structure in terms of regional variation, and investigate the haplotype diversity of these long-finned pilot whales. To complete these goals scientists collected 180 samples of muscle or skin tissue from long-finned pilot whales from stranding events between 1995-2019. DNA extraction and sequencing was completed for every individual, then compared to previously defined haplotypes of long-finned pilot whales in the region.

The study defined 9 haplotypes, with only 4 having been previously recorded in the North Atlantic. Haplotype S was the most found haplotype in the sample set, being present in 72% of individuals. Another trend noted was in single stranding events the individuals sampled were predominately male, while in mass stranding events the individuals sampled were predominately female. Lastly, most genetic variation was found to be within regions with large variation being between region groups. The proportion of genetic variation between regions was deemed nonsignificant.

The findings from this study are groundbreaking, being the first to prove mixing of matrilines at mass stranding events. For the North Atlantic, the haplotypes defined in this study were substantially higher than previously detected from the coast of Ireland and Scotland. In addition to this, it is hypothesized that the number of matrilineal pods in this area may be underestimated.

From a conservation standpoint, the data presented in this study is extremely important. For effective conservation management plans the information about genetic diversity and social structure of the long-finned pilot whales is essential. Along with this, the study was cost effective and opportunistic by collecting genetic data from stranded cetaceans.

For more information, check out the original scientific paper:

Ball, R et al. (2022). New haplotypes found in stranded long-finned pilot whales (Globicephala melas) in the eastern North Atlantic and adjacent waters. Marine Mammal Science. 38: 898-912. https://doi.org/10.1111/mms.12893

The Arctic is currently warming around four times faster than the rest of the world. Within the Arctic ecosystem, the European Arctic which is located in the Barents sea region and encompasses the Svalbard, Franz Josef land, and Novaya Zemlya archipelagos is warming twice as fast as the rest of the Arctic. A major indicator of this warming is the delay in sea ice formation. This change in sea ice arrival has a large effect on polar bear ecology. Apart from housing the polar bear’s main source of food, sea ice is also important for reproduction. Female bears in the Barents sea subpopulation rely on sea ice formation to reach denning sites, where they give birth to and nurse cubs. Female bears will dig dens in the snow where they will then give birth to their cubs and stay there until the cubs are developed enough to be able to go outside. The dens are reached from their hunting ground, sea ice, so when it is time to exit the den the bear family can easily reach a food source.

A study done in 2022 with Merkle and Aars looked at how climate change affects bears in the Barents sea subpopulation by exploring how the loss of sea ice impacts the availability of denning habitats for female bears and what the effect on their reproductive ecology means for the future of the subpopulation. This was done by estimating possible denning areas and mapping observed and predicted sea ice coverage. These two things were then used to estimate whether or not female bears can reach the denning site on time and what that will look like in the future. For the sea ice arrival estimation, they used observed data from 1979 up to 2020 and then predicted the arrival of sea ice from 2021 until the year 2100.

Overall they found that there is around 19,176 square kilometers of potential denning area (most of which is located on Svalbard and Novaya Zemlya). From that area 53% was reachable in 1980, 33% of sites are reachable currently, and that in 2090 and beyond there is predicted to not be any accessible denning habitats. In summary, there is an overall trend of late sea ice arrival and a decreasing access to preferred denning sites.

If female polar bears cannot reach their preferred denning sites, they will be further away from their food source: leading to thinner moms and thinner cubs. The overall study suggests that there will be a general decline in the Barents subpopulation in the future and that the population will become smaller and more concentrated around a single area. The population will be unable to spread out due to less ice access which will result in a decrease in genetic diversity which will lead to even more unhealthy bears. The future may be bleak, but for the European polar bear subpopulation it is even bleaker.

For more information, check out the original scientific paper:

Merkel, B., Aars, J. (2022). Shifting polar bear Ursus maritimus denning habitat availability in the European Arctic. Polar Biol 45, 481–490. https://doi.org/10.1007/s00300-022-03016-5

What Do Manatees Sound Like?

Do you think manatees moo like cows? Or do you think they don’t produce sounds at all? Well, they actually squeak, squeal, and chirp to express their different behaviors! Think of it as the various types of dog barks that express whether they are angry or excited. Manatees communicate in a very similar way that expresses different behaviors.

Are you interested in what Sea Cows sound like? Or interested in understanding their language? In the state of Florida, there lies the thousand pound aquatic mammal which is the Florida Manatee. They are commonly referred to as “Sea Cows” in which these aquatic mammals actually share a common ancestor with elephants. Unlike elephants, they have a small brian-to-body ratio for being large and intelligent marine mammals!. Further study needed to be researched on the social aspect of manatee calls and vocalization.

In a recent research under the Florida Atlantic University Institutional Animal Care and Usage Committee, the research team aimed to figure out whether the various manatee calls and vocalizations varied with behavior. They collected and gathered recordings of manatees from five different locations in the warm waters of Florida; Crystal River, Portosueno Park, Singer Island, and Harbor Branch Oceanographic Institute. They recorded five distinct calls (squeaks, squeals, high squeaks, chirps, and squeak-squeals) from manatees.  These types of calls were used to determine whether they were stressed, cavorting (physical interactions), resting, or feeding.

Researchers found that manatees vocalized using only three primary calls regarding behavior. The most common call were squeaks which indicated the animal was stressed based on the long duration and high frequency. High squeaks were correlated to calf-presence.  Manatees were also found to communicate more when there was calf-presence using both squeak and high squeak calls. High squeals were used when manatees were cavorting which is when they are in a higher state of arousal.

For more information, check out the original scientific paper:

Brady, B., Moore, J., & Love, K. (2022). Behavior related vocalizations of the Florida manatee (Trichechus manatus latirostris). Marine Mammal Science, 38(3), 975–989

In February of 2020, a humpback whale calf was killed during the crossfire between two mature males fighting over a female. The tragedy was observed at a breeding ground in the Mexican Pacific. The calf belonged to a female Humpback named CRC-15467, which has been researched and observed since 2010. Male Humpbacks have been escorting this female through migration along the coast between mating periods. Escort behavior has the same implication of a “dib” in human social interactions. All goes south when competition arises between males.

So could it be that the majestic, gentle giants of the ocean are not so docile as previously perceived? Could it be a “eat or be eaten” world?

CRC-15467 and her newborn calf were first spotted on January 13, 2020, with a heavily scared male companion. Just 36 days before its death, researchers estimated the calf to be less than 1 week old. The next intriguing glimpse of CRC-15467 and her calf was a month later, now with a party of escorts alongside. The pair were seen moving quickly along the coast, for three competing males were exhibiting aggressive behavior a mere 500m away from them. To say the least, the calf’s final 24 hours were chaotic.

During the early morning of February 19, 2020, the calf displayed a great deal of activity on its surface, indicating that it was healthy. During the 15 min observation period, CRC-15467 and her calf moved toward the coast. Females tend to seek shallow water as a tactic to avoid male harassment. At 10:33 am the competing escorts are sighted making their way towards the coast, ready to join the fight for a mate. Six minutes into the altercation (10:39 am), one of the whales reappeared at the surface and slammed into the water. Following the hit, a large pool of blood flowed to the surface. And in the blood floated the calf, lifeless and still, losing buckets of blood. The group of escorts, including CRC-15467, continued the chase down the coast leaving her calf without a second thought.  Once the waters calmed, fishermen who witnessed the tragedy contacted the proper authorities, the Federal Attorney General for Environmental Protection (PROFEPA). The calf’s body was sadly lost and unable to be recovered for future investigation.

These observations make us rethink how we look at the marine world and alter how we perceive social structures. Reminds us that natural selection is evident, and maybe “not judging a book by its cover” relates to more than just people. However, this is just one story; who knows what else occurs in the oceans just outside our sight?

For more information, check out the original scientific paper:

Ransome, N., et al. (2022). Escorting of a mother humpback whale (Megaptera novaeangliae) and the death of her calf during aggressive mating behavior. Marine Mammal Science. https://doi.org/10.1111/mms.12922

Maine’s rocky coastline has always been known to harbor hidden gems, ranging from the massive sea cliffs that stand tall and proud to the small critters that call this coastline home. In recent scientific news, a three year study focused on finding an accurate population size of southern Maine’s marine mammals has been concluded. It has always been known that right off the coast of Maine you can find a variety of interesting marine mammals, such as the harbor seal, gray seal, and various types of whales. But what has not been as well known is the accurate size of these marine mammals populations in areas like the mouth of the Piscataqua river. Following the three year study, conducted by Ann M. Zoidis and colleagues, it was found that the mouth of the Piscataqua river is called home by a population of over one hundred and fifty harbor seals, less than a dozen gray seals, and a few occasional rarities such as harbor porpoises and minke whales.

One might ask how such a project takes place, three years is a very long time to keep up with such a continuous survey across the water to count all those individual marine mammals. The answer being the dedication of researcher Ann M Zoidis, a fully assembled team of her peers, and some state of the art recording equipment with its software. Specially trained technicians were able to visually identify individual marine mammals in the water and then record such observations in a type of software called WinCruz, which would then map out all observations and check all entries for any possible recording errors. All of the research data recorded from the WinCruz software would then be uploaded into a second software called DISTANCE. This second software would take all data and format it into maps and statistics so that the research can be easier understood.

Aboard this sizable research vessel the team of scientists took to the water each month to make sure that observations were complete for the project to work out. Following the strict routine of using visual surveys to record data that was later uploaded into the two separate softwares, they followed this routine for all three years consistently and have just now finished putting the data together.

Concluding concepts taken from this research project is the large presence of harbor seals at the mouth of our beloved Piscataqua river, and low presence of other marine mammal life. So the next time you find yourself near the water make sure to keep an eye out for some fun little friends swimming around.

For more information, check out the original scientific paper:

Zoidis, AM., et al. (2022) Distribution and Abundance of Marine Mammals in the Estuarine Waters of the Piscataqua River, Maine, USA. Aquatic Mammals, 48: 25-35. https://doi.org/10.1578/AM.48.1.2022.25

Dolphins are known for many different things; Their playful nature, their intelligence and their grace in the water. But one thing that they are most well known for is their sounds, squeaks, and chirps. Many people would be able to identify a dolphin just by their vocals. Shown in a recent study done on the Pacific White-Sided Dolphins shows that there is much we still do not know about when it comes to how dolphins verbally communicate.

This study was the first research done on the types of sounds made and what they look like on a chart, also known as their contour, in the wild of Pacific White-Sided Dolphins. It confirmed that whistles are less frequently used than burst pulses. Surprising, not all types of dolphins whistle, in fact, there are three groups dolphin species are placed in. One group communicates with mostly whistles, this section can contain the commonly known Bottlenose Dolphin. The next group does not whistle at all with one of the more well-known species apart of this group being a Harbor Porpoise. Lastly, the group that our Pacific White-Sided dolphins are a part of is the one that only whistles a tiny bit. As said above their main communication is through burst pulses. A burst pulse is a strong sound that is mainly made up of just vibrations and not as much sound. Whereas a whistle can be heard as a high pitch noise, a burst pulse has a much lower frequency or sound to it.

The research was completed in the Pacific White-Sided Dolphin’s home of the North Pacific Ocean off the coast of Japan. Throughout the research, there were a total of 42 survey boats between 2014 and 2017 and over this time period they recorded a total of 62 hours and 41 minutes of sounds from these dolphins. These recordings included 183 whistles and 14,297 burst pulses! One of the main things these researchers go out of their finding was that the dolphins used these different types of sounds to communicate different things with each other. When it came to identifying the different type of whistling the scientitiscs looked at the rate whistle it would come in a show up on the graph. When a high rate whistle is shown it indicates that they were traveling, a medium rate whistle meant to forage and a low rate whistle meant that it was time to rest. The way that they could tell what rate a whistle was, was based on the whistle’s contour or shape when it would show up on their data screens as lines. If the lines went higher up in the chart it was a high rate whistle, a medium rate whistle would stay towards the middle of the chart and a low rate would show up lower on the chart.

If you would like to dive deeper into the whistles and bursts feel free to check out the research paper below:

Matsushiro, M et al. (2021) Contour variations and acoustic characteristics of whistle sounds emitted by Pacific white-sided dolphins in shallow coastal waters of the Sea of Japan. Marine Mammal Science, 38(3): 881-897. https://doi.org/10.1111/mms.12892

Summary: Marine microplastics are all over the world and including inside marine mammals. Through a comprehensive review of 30 studies Laura Zantis and her team showed how pervasive an issue microplastics are within the scope of marine mammals.

For more information, check out the original scientific paper:

Zantis, LJ et al. (2021) Marine mammals and microplastics: A systematic review and call for standardisation. Environmental Pollution, 269: 116142. https://doi.org/10.1016/j.envpol.2020.116142

Researchers in Mexico set out to find the biggest causes of harbor seal disturbances. The Pacific Harbor Seal is a local along the west coast and loves beaches just as much as any person. They use these beaches to rest, and most importantly to raise their pups. Nursing moms need these beaches to rest, as their journeys to sea are focused on refueling. Because of this, this resting period is extremely important.

The main question of this study was to figure out what was bothering the local seals, and to what extent they were being bothered. With many hard-working observers putting in many sandy hours, they were able to watch when seals were being disturbed, and for how long. They mainly were looking at nursing behavior, and whether said behavior was halted.

With lots of work, they discovered that people and cars were the biggest culprits. Cars, using beaches as a mini highway, caused the most disturbances in seals. They hypothesized that this is due to the large and loud noises that cars make. What is more interesting is that people walking the beaches caused more intense disturbances. This means that the disturbances lasted longer where the seals never returned for the day. The researchers assumed that this intensity of disturbance is caused by the vicinity, where people can get closer to seals then cars. They also suggested that humans historically hunted seals, causing them to be known predators.

The results of this study will help future biologists create a more seal friendly environment in the future. These observations and numerical data are important to represent more clearly what is going on. They can take this information and make better rules and regulations preventing high disturbances on these beautiful beaches.

All of this is crucial to understanding how to better help seals on our beaches. As we dream of sunny beach days, we must keep in mind that many animals also need the sandy dunes to live. The team suggesting better outreach and beachgoer awareness is going to be crucial to future prevention of seal disturbance. When out on the coast, remember to keep our blubbery friends in mind. Keep your distance, respect the wildlife, and enjoy all that the world has to offer!

For more information, check out the original scientific paper:

Ruiz-Mar MG, Heckel G, Solana-Arellano E, Schramm Y, García-Aguilar MC, Arteaga MC (2022) Human activities disturb haul out and nursing behavior of Pacific harbor seals at Punta Banda Estuary, Mexico. PLoS ONE 17(7): e0270129. https://doi.org/10.1371/journal.pone.0270129

There is a war over resources and space between us and the cute and charismatic bottlenose dolphins. That statement may be a bit dramatic, however, there is an overlap between human activities and bottlenose dolphins, especially in the Mediterranean. Fishing vessels and dolphins are looking for the same thing: fish. Bottlenose dolphins have even been found to seek out and follow fishing vessels to find food. How are these interactions between fishing vessels and bottlenose dolphins changing the behavior of  bottlenose dolphins? That is what a team of researchers led by Dr. Laura Rudd have discovered.

To dig deeper into the mystery of how fishing practices are affecting bottlenose dolphins, the researchers conducted hundreds of surveys from September 2016 to August 2020 off the coast of Montenegro in the South Adriatic Sea, across from Italy. They compared the behavior of dolphins when they were near fishing vessels to when they were not near fishing vessels. They noted if those vessels were from a small-scale, low-technology artisanal fishery or from a large-scale, high-technology commercial fishery. The four behaviors the researchers examined were diving, socializing, surface feeding, and traveling.

They discovered that the fishing practices of the artisanal fisheries had a smaller impact on the dolphins’ behaviors than the fishing practices of the commercial fisheries. In the presence of commercial fishing vessels, the dolphins’ socializing behavior remained the same, but their traveling behavior decreased, their surface feeding increased, and their diving behavior increased. In the presence of artisanal fishing vessels, dolphins’ surface feeding decreased while traveling, diving, and socializing did not significantly change. This means that commercial fishing vessels, and to some extent artisanal fishing boats, substantially changed the dolphins’ behaviors.

This study highlighted how the proximity between bottlenose dolphins and fishing vessels is changing bottlenose dolphin behavior in the short term, causing them to do things like  lengthening their dive intervals. In the long term, the close proximity between dolphins and fishing vessels will increase the chances of collisions and entanglement. This reliance on human activity for foraging can even lead to habitat displacement if the presence of fishing vessels continues to shift the bottlenose dolphins’ foraging behavior.

In the Mediterranean region, bottlenose dolphins are classified as a vulnerable population. While fish in the Mediterranean sea are an important food source for humans, they are important for dolphins too. The stresses put on these dolphins by fishing vessels increase the dolphins’ struggle to survive, making them an even more vulnerable population. It is important for us to be conscious of how human actions are affecting bottlenose dolphins in the Mediterranean.

For more information, check out the original scientific paper:

Rudd, Laura, et al. (2022) The Effect of Commercial and Artisanal Fishing Practices on the Behavioral Budget of Bottlenose Dolphins off the Coast of Montenegro, South Adriatic Sea. Marine Mammal Science. 38:990-1006.

Sea otters are marine mammals that belong to the Mustelidae family. They typically live near shallow habitats as sea otters dive at a maximum depth of 100 meters. Their diet contains fish and many invertebrates, such as sea urchins and clams. Around the 18 th to the 19 th century, sea otters were almost extinct because they were harvested for their fur. Currently, a group of sea otters in Southwest Alaska has been listed as threatened by the Endangered Species Act in 2005. The Endangered Species Act purpose is to provide a means where threatened and endangered species can be conserved.

Researchers have studied the genetic population of sea otters in the North Pacific since there hasn’t been significant attention in this area. They took 501 skin and muscle samples at 14 locations throughout Southcentral Alaska, Southwest Alaska, and the Commander Islands in Russia, specifically the Bering and Medny. For each sample, they took 13 microsatellite loci. Microsatellites are short segments of DNA that are repeated in a succession and loci is the location of the specific gene on a chromosome.

The researchers found that there is a high degree of genetic differentiation between the 14 locations and it follows the isolation by distance model. The isolation by distance model means that genetic similarities between populations will decrease as the distance between the locations increase. Another observation was that the sea otters’ genetics formed 6 geographic clusters. Based on these findings, they concluded that there is enough genetic variation between each group of sea otters that they can be given their own conservation management practices, especially since the Southwest Alaska group has been listed as threatened. Without having management practices, harvest rates of the sea otters can lead to overexploitation and can eventually decrease in production and biodiversity.

For more information, check out the original scientific paper:

Flannery, Blair G. et al. (2021) Genetic variation in sea otters (Enhydra lutris) from the North Pacific with relevance to the threatened Southwest Alaska Distinct Population Segment. Marine Mammal Science 38:858-880.

Sound is an important sense especially for harbor porpoises because they use sound to navigate, locating prey and predators and communicating. Pile-driving sounds are high sound pressure that levels in both air and underwater environments. Pile Driving sounds are created by human activates (ships, boats, oil rig sites, etc.). This causes stress and can mess them up when they are looking for food, locating prey and predators, navigating, and communicating.Image yourself eating food and someone across from you is eating with their mouth open and chewing loudly, it can get very annoying when you are just trying to enjoy your food. The researchers used a female harbor porpoise that was 9 or 10 years old and her hearing was responsive. They kept the harbor porpoise in a pool that had both a indoor and outdoor setting at SEAMARCO Research Institute in the Netherlands, where they conducted their experiment. They were going to use six different noise levels and record what happens to the harbor porpoise when hearing those sounds.

When the experiment began they turned on the level of sound they wanted to play and then turned the sound off for 1 to 5 hours because they wanted to observe what happened after. They began this experiment in April and ended in October 2020 and they didn’t conduct the experiment when it was raining or if it was windy. When all the sounds were played at random order, the tests were used to compare the distance of the harbor porpoise from the transducer and what was her respiration rate in baseline periods and test periods. The transducer is a machine that creates high-frequency sounds underwater.

During the baseline periods, the harbor porpoise swam in ovals in the outdoor pool and the distance from the transducer was low and her respiration rate was low, so it was similar to her regular baseline periods, but she never jumped out of the water. Baseline means that they are the results where no sound was played. During the testing period, piling sounds that were 1 and 3 the harbor porpoise moved away from the transducer and increased her respiration rate, piling sounds from 4 and 6 she also moved away. From sound 1 and 2, the harbor porpoise swimming speed increased and she never reduced her swimming speed relative to the baseline period, but from sound 1 and 2 she jumped out of the water sometimes.

Harbor porpoises can’t hear anything below 1 kHz (kilohertz) so to reduce these noises above 1 kHz , there should be a reduction of energy in high frequency sounds that are in the spectrum. Removing these high frequency energy can make mitigation more feasible and affordable for the harbor porpoise plus some countries are using air bubble screens that helps reduce sound levels that are above 1 kHz. If more fishermen and companies use air bubble screens it won’t mess up their way of life.

For more information, check out the original scientific paper:

Kastelein, R. et al. (2022). Behavioral Responses of a Harbor Porpoise (Phocoena phocoena) Depend on the Frequency Content of Pile-Driving Sounds. Aquatic Mammals, 48:97-109.

Washington’s sea otters (Enhydra lutris kenyoni) faced extirpation in the early 1900s as a result of the maritime fur trade. During this time, nearly a million sea otters were killed for their highly sought after fur pelts. The loss of these adorable critters would spell disaster for nearshore ecosystems as sea otters played an important role by controlling herbivorous invertebrates such as urchins and other mollusks.

In an effort to restore the population, The Washington Department of Fish and Wildlife released 59 sea otters from Amchitka Island, Alaska to two different release sites along the Washington coast. 29 sea otters were released at Point Grenville in 1969 and an additional 30 sea otters were released at La Push in 1970. In order to track and monitor a target population size and geographic range, information from sea otter surveys from 1977 to 2019 was gathered and analyzed to estimate abundance.

Upon reviewing the data, researchers found that the population size in their model increased from 21 in 1977 to 2,336 in 2019. The population of sea otters also increased with an annual average growth rate of 12.42% over the span of 42 years. In terms of geographic distribution, the model that the researchers used showed that in the next 25 years, the population and range of Washington sea otters will expand east and south of their current range.

So what are some takeaways about these cute and cuddly mammals? It has been shown that equilibrium density of sea otters in Washington state that was estimated from the study was higher than what was previously thought. The updated estimates of abundance and projections of population increase will help in the decision-making process regarding conservation and population status of our beloved sea otters.

For more information, check out the original scientific paper:

Hale, J. R., Laidre, K. L., Jeffries, S. J., Scordino, J. J., Lynch, D., Jameson, R. J., & Tim Tinker, M. (2022). Status, trends, and Equilibrium Abundance estimates of the translocated sea otter population in Washington State. The Journal of Wildlife Management, 86(4). https://doi.org/10.1002/jwmg.22215

Did you know northern fur seals can spend more than 80% of their time at sea? There are many types of seals, and one of the most charismatic is the northern fur seal which can often be found resting on a sandy beach or floating on ice until it’s time to eat. Their aquatic nature gives them the ability to dive to amazing depths of up to 600 feet to find prey, even though they are more commonly found diving around about one-third of that depth. These meat-eating aquatic mammals are also called pinnipeds, along with their close cousin, the walrus.

Northern fur seals are a member of the family Otariidae (eared seal) found in the North Pacific. They are commonly found on sandy or rocky beaches near open water. They prey on small fish, such as anchovies and squid.  To better understand the habits of these curious creatures, McHuron, and her colleagues further researched the variations in body mass and food intake that occur in northern fur seals. 

A total of forty-one seals were studied (21 in captivity and 20 in the wild). Wild fur seals’ ages were estimated, while the age of the captive fur seals was known. The groups observed were pups, juveniles, males, and females each at different stages of development.  In addition to their age, the different groups of fur seals were studied and measured to learn about their body mass as well as their food and energy intake. 

In terms of results, all groups showed changes in food and energy intake, as well as body mass with age. Two specific groups were highlighted: reproductive females and males. Reproductive females maintain a stable food intake until pregnancy when it approximately doubles. In male seals, researchers observed the “fatted male phenomenon”. This is when adult males build up energy reserves to sustain themselves while they attempt to hold and defend territories during breeding. In a nutshell, the daily intake and age of fur seals have the greatest effect on body mass changes. 

Over the past 25 years, the home of these charismatic marine mammals has increased by 0.05 degrees Celsius per year. This gradual change may seem insignificant, but the overarching effects are changing the marine food webs. The result of this is a negative effect on all marine mammals, including fur seals due to loss of prey. The researchers of this study provide new insight to aid fur seals when faced with the vulnerability of loss of prey. With a changing, warming ocean, the proposed findings will help future studies on other pinnipeds. 

For more information, check out the original scientific paper:

McHuron, E. A., Rosen, D. A. S., Carpenter, J., Leonard, P., Sirpenski, G., & Sterling, J. T (2022). Variation in body mass and food intake of northern fur seals (Callorhinus ursinus). Marine Mammal Science, 38( 3), 1160– 1181.

Manatees are herbivorous marine mammals also known as sea cows. They are a friendly species that are amused easily and mean no harm to us humans. Having said that, we are an increasing danger to them. Unfortunately, as we increase human activity and tourism in waters where manatees are present, the risk of boat collisions and strandings also increases drastically. When a marine mammal is stranded, it means that they could either be dead on the beach or floating in the water, or alive, and most likely injured, on the beach and cannot return to the water on their own. The Belize Marine Mammal Stranding Network documents the strandings of all marine mammals in the area, while Jamal Galves and other researchers analyzed 23 years of their documented data to find patterns with Antillean manatees.

Antillean manatees, one of the many species at risk, are found around the coasts of Central America and the northeastern portion of South America. They are considered endangered due to significant mortality rates, and one of the leading causes of their mortality is collision with watercrafts. According to Jamal Galves and his accompanying researchers, between 1997 and 2019, 451 Antillean manatee strandings were reported in Belize and 376 of them were verified. Of the 376 verified strandings, 131 were from watercraft collision, accounting for almost 2/3 of the total strandings. The rest of the strandings were from other causes, such as dependent calves, poaching, and entanglement.

Clearly, manatees suffer the most from being struck by boats and other watercrafts, which is something that can be changed by an implementation of regulations and rules that humans must follow. The research done by Jamal Galves et al. was done to push the idea that boating regulations must be put in place in order to save manatee species from endangerment and extinction. With the implementation of no-wake zones where there is an abundance of manatees and regulation of tourism in manatee’s native waters, the threats to the Antillean manatees may be reduced.

For more information, check out the original scientific paper:

Galves, Jamal et al. (2022) Analysis of a long-term dataset of Antillean manatee strandings in Belize: implications for conservation. Oryx, 1-9. doi:10.1017/S0030605321000983

The deep ocean is cold, dark, and largely a mystery. Although many challenges arise from living and diving to the ocean’s twilight zone, many creatures are still inhabitants of this deep realm. Deep diving gives us a peek into understanding oceans with a “full ocean” approach especially in a time when the oceans are changing at drastic rates. The secrets of deep diving mammals can help answer questions about the impact of carbon transfer between the depths and the ocean surface, fisheries in the deep ocean, mammal conservation, and the connectivity between humans and the ocean.

The deep ocean, 200 meters and below, comes with severe challenges like low light, high pressure, chilly temperatures, and low oxygen levels. However, animals like the short-finned pilot whale have found ways to dodge these challenges. They’ve adapted special reflective tissue in their eyes that help them guide through the darkness or use vocal sounds to communicate and find prey. Marine mammal species can also perform an inhuman act of holding a breath while submerged for extensive periods of time. There is no end to the miraculous adaptations marine mammals have formed to dive into the ocean’s twilight zone, but why bother? What is down in the depths of the deep ocean that can not be found closer to the surface?

The ocean’s twilight zone offers more food sources for some marine mammals like the elephant seal who deep dive to hunt larger populations of prey and also benefits from some prey swimming slower and becoming easier to catch due to less oxygen at ocean depths. On the flip side, animals can also escape to the dark to flee their predators because the deep ocean can be a perfect hiding spot.

Deep diving is also used as nature’s GPS to marine mammals. Although humans may not be able to detect it, marine animals can read environmental cues and use gradients of the deep ocean to navigate and determine direction. Studies indicate that Hammerhead sharks deep dive and can sense the magnetic field which is three times stronger at ocean depths. This allows them to use the magnetic landscape to guide them during migrations.

The ocean’s twilight zone is suggested to provide other benefits to marine animals. For example, it may help marine mammals to evict parasites who may not be able to survive in deep harsh conditions. Deep diving may also allow for more social interaction since shallower waters have more noise, increased energy saving, and increased ability to regulate body temperature.

Going into the future, it is important to recognize that deep diving is prevalent among many large marine mammals and that it may help answer our questions about the ocean ecosystem.

For more information, check out the original scientific paper:

Braun, Camrin D. et al. (2022) The functional and ecological significance of deep diving by large marine predators.  Annual Review of Marine Science 14:129-159.

How hard do you think it would be to protect your child in the open ocean? Humpback whale mothers spend a lot of time with their young, staying near them and keeping them safe. Previous studies done off Hawai’i Island have shown that, during the day, mothers and their calves are typically in shallower waters where there are less risks, such as harassment by males looking to mate, who tend to stay in deeper waters.

A recent 2022 study looked at humpback whales off West Maui, Hawai’i, to see if the whales there followed similar daily movement patterns. They looked across the ocean and recorded every mother-calf humpback whale pod they saw. They used specialized technology to collect their geographical location, as well as the location and type of all vessels, and the depth and terrain type across the survey area.

The results found that mother-calf pods (calf-pods) actually moved into deeper waters over the course of the day. Whales without calves (non-calf-pods), such as males, had a pretty constant depth throughout the day.

They also looked at calf-pod versus vessel depths. Nonwhale-watching vessels kept a relatively constant depth throughout the day, whereas whale-watching vessels moved deeper throughout the day, with the goal of being where the whales are. This means the nonwhale-watching vessels are undesirable to the whale calf-pods, forcing them into deeper waters where they also prefer not to be. They are unable to avoid whale-watching vessels, as those vessels follow the whales wherever they go.

The main finding of this study was that mother-calf pods off West Maui Island actually move into deeper waters throughout the day to try to avoid nonwhale-watching vessels, in contrast to off Hawai’i Island, which had almost no human or vessel interference at the time. This disruption of their daily depth trends can put them at risk to other issues, such as male harassment, which could distract the mother from her calf, putting the calf in potential danger. As a side note, showing how big of an issue this could be, mother-calf pods have also been found to stay over rugged terrain in the evenings as opposed to flat terrains. This is because the males are more active at that time, and the rugged terrain may be a way to disrupt whale sound waves, making it harder for the males to locate females. This is only one of the ways that humans negatively impact marine mammals. The health of the ocean and its inhabitants is critically important, and humans have massive negative impacts on it. Special care and attention is needed to preserve marine ecosystems before it’s too late. Issues like this are harder to combat, but always do a little extra research before planning vacations to make sure you minimize your effects on animals and the environment.

For more information, check out the original scientific paper:

Pack, Adam et al. (2022) Diurnal increases in depths of humpback whale (Megaptera novaeangliae) mother-calf pods off West Maui, Hawaiʻi: A response to vessels? Marine Mammal Science 38:1340-1356.

You’ve heard people compare marlins to cheetahs and blue whales to elephants, well, dalls porpoise is next in line. Over years of extensive research, we still know very little about marine mammals. Paul Ponganis’ group of scientists set out to gather information from past research; specifically focusing on Ridgeway and Johnston’s study from 1966 which focused on the diving behaviors and various biological factors (weights, metabolism, and other adjacent qualities) of dalls porpoise, pacific white-side dolphin and the Atlantic bottlenose dolphin. Utilizing the data collected from years past, they formulated a variety of equations and speculations connecting the morphology and behaviors of these dolphins.

They took particular interest in diets, inexpensive and expensive tissue masses, and various weights of other parts of the body. Inexpensive tissue means muscle, bone, and blubber and higher percentages are often associated with deep diving mammals whereas expensive tissues include the brain and spinal cord and are associated with the beloved bottlenose dolphin (due to their high intelligence). They also noted the specific muscle, lung, and heart masses of these dolphins and graphed differences. Finally, they took note of the total body 𝑂2 stores; this means the amount of oxygen an organism can store in its body with the two major sinks being blood and muscle. This is estimated using a variety of equations and factors within the species that impact how fast O2 is used, stored, or otherwise, and is used as an indicator for deep divers and fast swimmers.

After vigorous studies of the datasets, tables, and graphs, they determined that the dalls porpoise had the largest heart mass, largest inexpensive tissue ratio (indicating it can be a deep diver), and one of the largest total body 𝑂2 stores in cetaceans and marine mammals with only two whales (sperm and beaked) and three seals (Weddell, elephant, and hooded) being higher! All of these indicate a new potential deep diving marine mammal to the scientific scene. Coupling this data with what it could mean and the observations that have been made in the wild, the dalls porpoise has been noted to be remarkably fast and athletic, perhaps Ponganis’ team has discovered a deep diving athlete!

To wrap up their study, they would comment on the Dalls porpoise’s remarkable anatomical similarities to a racehorse due to its high inexpensive tissue ratios, specifically in reference to heart, lung, and muscle mass, which racehorses are well known for and gives them their incredible athletic abilities.

All in all, this study aimed to put past collected data into perspective for new studies, but it also emphasized the lack of research on marine mammals which surprises many and can act as an inspiration for a new generation of marine scientists.

For more information, check out the original scientific paper:

Ponganis, P. J., Fujise, Y., & Miyazaki, N. (2022). Morphology and physiology in some small pelagic cetaceans: Is Dall’s porpoise a deep diver and a thoroughbred of the sea? Marine Mammal Science, 1– 28.

Each year, tens of thousands of krill make their way to warmer waters during the summer months. Following close behind: the blue whales. Blue whales will time their migrations each year from breeding to feeding grounds to avoid missing peak prey abundance. During the winter months, blue whales use their energy to breed and will then travel to feeding grounds to prepare for the next season.

A group of scientists have recently conducted a study, using the social and mating calls of blue whales, to determine the timing of this migration. What they found at the end of the study was that the blue whales were arriving at the feeding grounds one month earlier than they were when the study was first conducted. However, their departure time remained the same. This timing aligned perfectly with the change in warmer ocean temperatures, earlier in the year. The main question that remains: What implications does this have for the blue whale population, as ocean temperatures continuously rise?

With temperatures becoming warmer earlier in the season, blue whales must adjust their timing to survive. However, the departure time of the blue whales remained the same for the entirety of the 10-year experiment. This climate induced adjustment leaves blue whales with increasingly less time away from feeding grounds. If this pattern persists, will the whales have enough time to successfully mate? In addition to a loss of mating time, blue whales could now be exposed to increased ship traffic and fishing gear for longer periods of time, as well as in locations that fisherman do not expect. This simple adjustment of migration timing, due to changes in ocean temperatures, could lead to life threatening implications for the blue whale population. While this information is integral in our understanding of blue whales behavioral and physiological traits, conservation strategies (like restricting fishing to specific times and places) need to be implemented in order to adjust to their new schedule. If they aren’t, balance in the oceans could be offset and its unknown how this may throw off the balance of life as we know it.

For more information, check out the original scientific paper:

Szesciorka, A.R., Ballance, L.T., Širović, A. et al. (2020). Timing is everything: Drivers of interannual variability in blue whale migration. Sci Rep 10: 7710.

The Steller Sea lion and California Sea lion are both at the top of the list for being the most common sea lion in the US. Many may think this is a positive fact, but in the scientific field, it is more of a concern. This causes concern for scientists researching marine life because it may cause an unbalance or other social problems among other marine mammals in the environment. In a recent study on the prey consumption between the Steller Sea Lion and  California Sea Lion, data showed a significant outcome that there was an abundance of sea lions in one area and they were only hunting a select few species of fish. This outcome is a concern scientists sometimes face. When only a couple of species of fish are hunted at a time, other species tend to grow into more significant populations and soon become overpopulated in an area. This action leads to becoming a problem for the environment around them. Not only do scientists face this problem, but while research was being conducted, an observation was made on the consumption of sea lion pups and their mothers. This adds to the concern of prey consumption, because not only do mother sea lions need to hunt their prey for themselves but they need almost double caught and consumed just so they can provide for their pups. Researchers and Scientists are still observing these mammals and examining what other concerns there may be and how they can be fixed down the road.

For more information, check out the original scientific paper:

Scordino, J.J., Akmajian, A.M. and Edmondson, S.L. (2022) Dietary niche overlap and prey consumption for the Steller sea lion (Eumetopias jubatus) and California sea lion (Zalophus californianus) in northwest Washington during 2010–2013. rep. Neah Bay, Washington: National Marine Fisheries Service, pp. 39–54.

Depending on where you live one truth may quickly become apparent to you; humans make a ton of noise. In the morning you may step out of the house and encounter cars, trucks, motorcycles flying by at incredible speeds with even more incredible amounts of noise. As you go about your day you may encounter much more irritating noises, sirens, and construction. All to return home and repeat the next day; it may seem tempting to go off grid and get away from it all. While this thought is nice, our wild spaces are far from free of this noise pollution.

Marine mammals such as dolphins, seals, and whales are under constant stress from noise pollution. Noise pollution that causes stressed behavior in these animals that would not be seen without the presence of the increased noise. In the marine environment mammals have to deal with underwater noises like pile driving, sonar, engines, to name a few. Knowing this it is important to understand how these marine mammals respond to these stimuli in order to effectively adjust how these practices are implemented in marine environments that these mammals inhabit.

To do this Brandon Southall, a professor of marine science at University of California Santa Cruz, developed a scale in order to assess how certain noise exposure affects marine mammals. The scale is graded from 0-9 assessing the responses that the mammals react to stimuli.

Southall’s noise criteria scale has been applied to numerous observational studies over the last few decades. These studies aim to look at interactions between specific criteria and an individual, species, or population in a designated area. One of the first and most telling noise exposure interactions was the reaction of harbor porpoise populations and pile driving (a process in which poles are driven into soil with heavy machinery) in their local environment. What was seen over the course of three different studies was an almost exact replication of behavior with each population registering scores of a six. Another instance of the scale being applied is studies on beaked whales where the animal was subjected to sonar. When the whales interacted with the sonar there were response severities that registered a seven on multiple occasions.

The marine mammal response severity scale is important as it allows us to gauge our interactions with marine mammals in a way that allows us to adjust how these noises are regulated in a marine environment. If a species is sensitive to a stimuli it may be beneficial to remove that stimuli from an environment altogether or simply limit the use of it.

For more information, check out the original scientific paper:

Southall, B. L., Nowacek, D. P., Bowles, A. E., Senigaglia, V., Bejder, L., & Tyack, P. L. (2021). Marine Mammal Noise exposure criteria: Assessing the severity of marine mammal behavioral responses to human noise. Aquatic Mammals, 47(5), 421–464. https://doi.org/10.1578/am.47.5.2021.421

Like humans, dolphins spend a lot of time in familia groups. Unfortunately due to human activity we are beginning to see fewer of these groups. Recently a group of scientists in North Carolina researched a group of dolphins. Dolphins are greatly affected by human disturbances. For example, fishing gear that was potentially left behind can trap dolphins despite them being intended for smaller fish. Noise from boats like military vessels that may be using sonar is another example of human disturbance.

These outside influencers negatively impact the distribution of the dolphins, whether by avoiding noisy areas or, unfortunately, in some cases, death. This group of scientists wants to track the number of dolphins found along North Carolina’s coasts, keeping track of where and how many dolphins are spotted. A similar study occurred ten years prior, where scientists created a catalog of the number of dolphins in the area. The recurrence of this study shows how pertinent it is that we take the necessary measure to ensure we are protecting these dolphins and future generations.

To do this, scientists sampled about 547 individual dolphins across three sampling sessions. They focused on two estuaries, in the north, and the south, along the coast. An estuary is the beginning of a river where coastal water and river streams mix. During these three sampling sessions, they could map where the dolphins were most commonly spotted, how often, and whether they were in groups or alone.

Of the 547 individuals spotted, 201 had been tagged from the previous counting ten years prior. They also found that the dolphins were most abundant in coastal waters and estuaries. However, only a few were spotted entering both. Based on their finding, these scientists concluded that these dolphins have incredibly complex social structures and thus would need to conduct further research. In addition, smaller groups would require different conservation efforts, considering whether they are found in coastal waters, estuaries, or both.

For more information, check out the original scientific paper:

Hohn AA, Gorgone AM, Byrd BL, Shertzer KW, Eguchi T. (2022) Patterns of association and distribution of estuarine-resident common bottlenose dolphins (Tursiops truncatus) in North Carolina, USA. PLoS One. 17(8):e0270057. doi: 10.1371/journal.pone.0270057. 

Many of you most likely have never heard of a Bryde whale before; if you have, you may have mistaken it for another species! There are several different subspecies of Bryde whales. Still, I am focusing on Balaenoptera edeni brydei and B. e. Edeni, they are both found in the waters around New Zealand. Sahar Izadi, et al, asked the question of how these whales are different from other baleen whales and how they manage to survive in these warm unproductive waters. Since these whales do not migrate like most whale species they can often be seen feeding on both zooplankton and fish.

What makes these whales special is that they use surface head slaps as they lunge to obtain prey. This strategy uses a lot of energy so most people are unsure how this whale manages to be productive in these warm waters. Using many different strategies such as drones, harmless self-de-attaching tags, and observation scientists were able to learn more about the strategy that this whale now does. These strategies were useful in tracking and seeing where and how deep they feed. It was discovered that 91% of the 102 surface lunges on zooplankton and 8% percent on fish, while no head slaps were used for fish. This data is necessary because 20 years ago a study was done and it was discovered that the whales mainly feed on fish and now they prefer and mostly eat zooplankton. Now they were also discovered to only feed during the day and stay resting during the night. This is a direct sign that climate change or overfishing is impacting these marine mammals. Their prey is disappearing due to those issues stated. Since these non-migrating whales can survive in this ever-changing environment due to climate change, they provide hope for prosperity in the growth of these whales’ population.

For more information, check out the original scientific paper:

Izadi, S., Aguilar de Soto, N., Constantine, R., & Johnson, M. (2022). Feeding tactics of resident Bryde’s whales in New Zealand. Marine Mammal Science, 38( 3), 1104– 1117. https://doi.org/10.1111/mms.12918

The climate is changing the landscape for polar bears and other charismatic animals of the arctic. Polar bears (Ursus maritimus) and many other arctic species have undergone long-term population declines in large part due to habitat loss and geographic isolation between habitats (fragmentation). The authors of “Variation in Beaufort Sea Polar Bear Habitat Use” wanted to analyze how polar bears moved across the landscape, and more specifically, the habitats they used at different times of the year. This study took place in northern Alaska, and they believed that monitoring how an at risk species used habitats on the landscape could provide insights to a greater understanding of population level responses. These include the overall loss of sea ice, the location of prey on the landscape, and warming temperatures.

To accomplish these goals the authors played a game of tag with the polar bears! Yes, the researchers captured polar bears and placed GPS tags on a subset to best understand their movements. These GPS tags were in the form of collars fitted around the bear itself, and collected a location (latitude and longitude) every four hours. It is crazy how much technology has improved to aid in the understanding of species and their movements!

The next step for the research team was to go through and observe trends in the massive dataset that was collected. They divided each collected location into four seasonal categories: winter, spring, summer and autumn. Next, they utilized a statistical model to estimate the preferences of the individuals that were tagged in the study.

The researchers found some very interesting results upon reviewing the data. For instance, sea ice was used by the subset of bears almost uniformly. This means that no surprise, polar bears follow the ice when making decisions about where to go. Next, they found that there were differences between how mamma and papa bears used ice seasonally. All bears used locations closer to shore in the winter and spring, but many moved to areas further in the summer. The researchers believed that this was to follow the ice as it represents the most efficient form of foraging habitat for the bears. Lastly, they found that moms used landfast ice in the spring, allowing the cubs to hunt seal pup dens. This provides the cubs with a nutrient rich food source and an escape from older enemy polar bears who could be looking for a quick meal.

So what is next for these charismatic species of the arctic? Well it is clear that their landscape is changing rapidly. With less ice on the surface due to warming temperatures, it could mean less energy efficient hunts of harbor and gray seals. This could lead to starving and exhausted bears in the summer months. It is important for us to make smarter decisions in terms of energy and resource usage in the future. The livelihood of these beloved species depend upon it!

For more information, check out the original scientific paper:

Johnson, A.C., Derocher, A.E. (2020) Variation in habitat use of Beaufort Sea polar bears. Polar Biol 43, 1247–  1260.

“Evidence that bottlenose dolphins can communicate with vocal signals to solve a cooperative task” is one study that made new and interesting discoveries. This experiment was conducted at the Dolphin Research Center (DRC) in Grassy Key, FL between January 2018 and August 2019. The goal was to determine if the dolphins can use vocal signals to coordinate their behavior in a cooperative button-pressing task.

Bottlenose dolphins are well-known for cooperating in the wild. One example is their feeding strategies, which require coordination because they have to work together to obtain food efficiently. Another example is male alliances, requiring cooperation between individual males when acquiring females of interest for mating.

The subjects of this study were four common bottlenose dolphins. The first pair consisted of Aleta, a 33-year-old female, and Calusa, a 17-year-old female. The second consisted of Delta, a 9-year-old male, and Reese, a 7-year-old male. They were all born in DRC and lived in natural seawater lagoons. The members of the female pair lived together during this study and the members of the male pair lived together as well.

The task was that each pair had to swim across the lagoon where each individual would press an underwater button within one second of their partner. It was considered unsuccessful if there was more than a one second delay.

Both pairs used vocal signals to communicate during trials with increasing levels of difficulty. These tests ranged from the pair partners together to delays between pair partners to no visibility between pairs during the button-pressing. The researchers recorded the physical and vocal behavior of each pair during each trial by using an underwater microphone to find vocalizations. This helped determine how and when individuals communicated with each other.

Figure 1 (shown above) shows how the experiment was set up for each trial. For the first 4 trials, the buttons were placed directly next to each other where the figure is labeled A. The 5th and 6th trials had the buttons placed facing away from each other where it is labeled B. The 7th trial had the buttons placed halfway across the lagoon where it is labeled C. For the last trial, the buttons were placed on opposite sides of the lagoon where it is labeled D.

The figure (shown above) shows the vocal behavior results by each pair during the experiment. Graphs A and B show the presence of whistles vs. the time between button presses. The horizontal lines represent the cut off for a successful trial. Both the male and female pairs were successful with or without vocalizing. Graphs C and D show the trial outcomes vs. number of whistles. The male pair proved much more successful in solving the task when communicating.

Both pairs were capable of using vocal signals to solve cooperative tasks. The whistles could be used as a signal to coordinate pressing the button. An interesting finding was that whistle timing proved to be one of the most important parts of the task. Whistles prior to button pressing implied that most likely the dolphins used whistles to decide when to press.

The ultimate conclusion was that some bottlenose dolphins have the ability to communicate and work together to solve tasks.

For more information, and to see the figures, check out the original scientific paper:

King, Stephanie et al. (2021). Evidence that bottlenose dolphins can communicate with vocal signals to solve a cooperative task. Royal Society Open Science. 8: 202073.

How much energy do we as humans use daily?

Well, we have some pretty good technology such as smartwatches that track our steps and alert us of unusual activity. But a study is working on finding a baseline for the daily movements of Marine Mammals like the Bottlenose Dolphin.

The study was published by a team of researchers at Duke University in 2022 with a team of veterinarians, students, and specialists. They began this study to get a baseline of the cost of energy for bottlenose dolphins and then apply it to free-range Dolphins to get a better idea of how much energy wild dolphins use daily and how that may compare when human-induced factors come into play. With recent Anthropogenic (human-caused) factors that can disturb the environment of Marine mammals, this becomes important to know.

Human-induced factors can cause cetacean species like Dolphins to use more energy speed away from perceived threats these can come from noise pollution, increased trade routes, and possibly invasive species. This study investigated captive male dolphins ages 10-34 years old and recorded them swimming 9 laps each in an enclosed space.

So, how do we measure how much energy marine mammals use during each lap?

Two devices are used. The first device measured breathing while completing the 80m laps. The second device measured and recreated how the dolphin moved, whether up, down, side to side, or rotations.

So, what did they find in this study?

Well, overall, the study found that as the dolphins completed the laps back-to-back, they used much more energy on their last few laps. This can be compared to running laps on a track, in the first lap you start with the most energy but by the time you get to your last lap, it is harder to finish. The results of this study created a baseline for male dolphins in captivity and how much energy they use.

This is a start, but the study is looking to apply this to wild dolphins that swim much more in a day foraging and looking for mates. While also swimming through a stronger current and increased drag on the open ocean.

This is hoping to predict the cost of daily locomotion when anthropogenic effects add to the amount of energy Bottlenose dolphins use while trying to avoid or swim away from increased noise, large boats, and possible human interference come into play.

For more information, check out the original scientific paper:

Allen, Austin S., et al. 2022. Dynamic Body Acceleration as a Proxy to Predict the Cost of Locomotion in Bottlenose Dolphins. The Journal of Experimental Biology 225 (4). https://doi.org/10.1242/jeb.243121.

The rapid emergence of marine structures, such as marine renewables and port infrastructures, has led to the increase in man-made structures in marine environments.

Scientists’ knowledge of species interactions with human-structures is limited because it’s difficult to observe such interactions. Understanding whether marine life avoids, interacts with, or adapts to these structures is essential information for future developments to conserve marine species and their ecosystems.

Off the coast of Shetland, UK, the use of an unmanned drone in early 2022 captured aerial video footage of a predator-prey interaction around a marine infrastructure.

A group of 27 killer whales (Orcinus orca) entered an inlet where they began to mill around a blue mussel farm. Soon after, video footage was used to observe a harbor seal (Phoca vitulina) seeking refuge within the mussel farm to avoid the group of foraging killer whales. The drone provided valuable insight into how man-made structures are being incorporated into predator-prey foraging strategies.

Examining the 38 minutes of video footage provided by the drone proved critical for revealing how predators and prey might behave around a man-made environment.

After reviewing the footage, the researchers split the data into two parts: behaviors exhibited by the killer whales and behaviors exhibited by the harbor seal.

In terms of the killer whales, many different behaviors were recorded. However, the most important data was that the killer whales spent 73.7% of their time interacting with the mussel farm, these interactions usually only occurred when the killer whales were seen actively tracking, observing, or pursuing the seal (aka. predation activity).

As for the harbor seal, it spent 94% of its time interacting with the mussel farm in some way.

Emily L. Hague and her team of researchers were able to observe previously undocumented behaviors from the video they recorded of predators and prey interacting with a man-made structure. In general, structures could act as refuge for prey, but hinder feeding for predators. Or, structures could act as ecological traps for prey.

On a broader note, entanglement risks by man-made structures could pose real threats to marine life, so Emily L. Hague and her colleagues urged that more research was needed to figure out ways to prevent entanglements with structures in the future. Understanding the potential risks of man-made structures should be taken into consideration when modifying and developing coastal areas.

For more information, check out the original scientific paper:

Hague, Emily L. et al. (2022) Predation in the Anthropocene: Harbour Seal (Phoca Vitulina) Utilising Aquaculture Infrastructure as Refuge to Evade Foraging Killer Whales (Orcinus Orca). Aquatic Mammals, 48:380-393.

Marine mammals are beloved around the world for their charisma and adorable faces, as well as their beauty in nature. Scientists and civilians alike often ponder the question; what are the effects of climate change on marine mammals? And what can we do to help? Due to the massive scale of climate change and the shortage of studies that look into its effects, there is little proven evidence of its impacts on marine mammal species. Despite this, there have been countless observations made about indirect effects linked closely with changing climate, many of which affirming that it’s a serious concern that should be further studied. Many believe it should be made the focus of marine mammal research globally, so that we can understand how to better help these species in the future.

In a recent study conducted by a team of researchers, over 1,000 journal articles were read and analyzed, looking for evidence correlating previous predictions about climate change with current documentation on how marine mammals are being affected. Rather than establishing the most severe effects or what species are being most strongly impacted, the team focused on the evidence provided to confirm these predictions, determining if the effects themselves had been documented and supported with data, or presumed likely based on observations made alone. The team also hoped to suggest research and conservation methods that would help with finding new evidence and expanding our knowledge about climate change. After analyzing the articles about numerous marine mammal species, it was concluded that effects of climate change including warming coastal temperatures, loss of sea ice, and sea level rise resulted in reduced health and population numbers of many vulnerable species. Range shifts of main prey sources followed by marine mammals themselves, has led to increased mortality due to ship strikes and fishing gear entanglements in several whale species, including the critically endangered North Atlantic right whale. Sea level rise and unpredictable weather has caused loss of terrestrial habitat for species like the Hawaiian monk seal that have experienced declines in pup survival rates as well as increased interaction with humans on beaches.

Among these species mentioned were many others that encountered similar concerns, primarily through what’s believed to be the indirect effects of changing climate. For all the articles with actual data, there were countless others that could only make predictions on how climate change is affecting different species because there is just not enough information to truly justify their reasoning. With so many possible factors that can contribute to a species decline, it can be difficult to tell whether it is climate change driving those consequences or something else entirely. There is hope that with continued climate change-based research, enough evidence and information can be gathered to help improve the conditions these marine mammals face. Climate change is a pressing issue we all share and it’s up to us to stay aware and help conserve and protect the marine mammals that bring joy to so many.

For more information, check out the original scientific paper:

Gulland, Frances et al. (2022) A review of climate change effects on marine mammals in United States waters: Past predictions, observed impacts, current research and conservation imperatives. Climate Change Ecology, 3:100054.

When looking at a seal, sea lion, or walrus, what’s the first thing you notice? Their fat blubber filled body? Maybe you look at their fins and tails that they use for swimming. If you’re inclined to look at their adorable little face then maybe you have observed their head size and whiskers!

One study performed and observed by Milne et al., compared the size of the infraorbital area (eye area behind the skull) to the vibrissae, which are the whiskers of mammals. This study was performed to determine if there were evolutionary changes going from terrestrial animals to aquatic. To see if there is a correlation, scientists compared skulls of land-dwelling carnivores to those of seals, sea lions, and walruses.

All of the pinniped skulls were obtained from various museums in Europe, while the data for the carnivores came from a previous study done by Muchlinski in 2010. The skulls were measured for the eye area in the back of the skull and recorded. For the whisker measurements, Milne et al., counted the individual follicles upon the skin of the species from the museums for the pinnipeds while the carnivore data was again gathered by Muchlinski, 2010.  To analyze the data that was collected, a phylogenetic tree was utilized along with some statistical analysis to determine a phylogenetic signal.  If the phylogenetic signal was high, then the species was evolving, and conversely, if the signal was low, it showed that it leaned on life history and ecological traits.

The conclusions of the study were that the eye space and the whiskers were indeed correlated within pinnipeds, directly demonstrating the evolution for the aquatic mammals. Additionally they discovered that the eye space is larger in the walruses compared to the seals and sea lions. The final conclusion that was drawn from this study was that as the size of the species increases, the number of whiskers increases as well. Across the species of both the carnivores and pinnipeds, their whiskers are a shared homologous trait. The skull also shows changes in teeth for the pinnipeds which indicates and helps prove their evolutionary claim.

For more information, check out the original scientific paper:

Milne, A. O., Muchlinski, M. N., Orton, L. D., Sullivan, M. S., & Grant, R. A. (2022). Comparing vibrissal morphology and infraorbital foramen area in pinnipeds. The Anatomical Record, 305(3), 556–567. https://doi.org/10.1002/ar.24683

The humpback whale is a species of baleen whale that have Adults ranging in lengths from 14–17 m and weigh up to 40 metric tons. They are Filter feeders that have a distinctive body shape, with long pectoral fins and a knobbly head. In a recent study, most humpback whales are commonly found in the near-shore waters of the Hawaiian islands between late fall and mid spring (November–May), with a peak in mid-winter (January–March). Hawaiʻi and other low latitude waters are considered mating and calving areas. Most females are believed to mate in these waters and return the following year to calve.

The shore-based observation site used in the study is located on the northwest coast of Hawaiʻi Island, overlooking Kawaihae Bay at an elevation of 63.6 m. The site is known as “Old Ruins” because of the stone wall remnants of a Hawaiian village on nearby hillsides. The waters of Kawaihae Bay are steeply sloped, leeward waters, typical of volcanic islands like Hawaiʻi. In this study, they conducted scan samples once per week in each of four time-blocks to ensure that scans were conducted at various times during daylight hours to capture any patterns that recur every 24 hours which is also known as a diurnal trend. Data was collected between late January and late March from 2001 to 2019.

A total of 366 scan samples were collected between 2001 and 2019. An analysis was conducted after the 2018 season to test for diurnal effect. Since no effect was detected, the protocol for 2019 removed the time-of-day requirement.

Models indicated that whale numbers and crude birth rate fell when climate indices reflected warmer water on high latitude feeding grounds in the North Pacific. The largest marine heatwave ever recorded occurred in the Northeast Pacific Ocean over several years, starting in late 2013 causing the drop in crude birth rates and less sightings. During the 2014–2016 marine heatwave and the persistence of lower calf production in the study suggested that the ecological disruption affected whales from various North Pacific feeding areas.  Numerous other marine predators appear to have experienced similar declines.

Although the mechanisms by which these oceanic changes directly or indirectly affect humpback whales are not well understood, there is evidence that these linkages exist. During the 2014–2016 marine heatwave, the value of the data time series became very apparent.

The increase in the number of humpback whales in Kawaihae Bay over the past 19 years is encouraging but the sudden changes in climate bring negative consequences to the whales. If whale numbers remain low over the next few years, a general population decline is the most likely hypothesis. Only time and systematic monitoring will tell.

For more information, check out the original scientific paper:

Frankel, Adam S. et al. (2022) Humpback whale abundance in Hawai‘i: Temporal trends and response to climatic drivers. Marine Mammal Science.38:118-138

A recent study released in March 2022 shows the resting metabolic rates of Weddell seal pups in air and in water during developmental stages. Scientists wanted to understand how much energy during development was going to be exerted during periods of being submerged in water or on the ice. To begin the experiment, week one testing was only done in the chamber for air’s resting metabolic rate and excluded water’s metabolic resting rate. For week three and beyond, the pups were tested in air and water for the resting rate.

The air tight chamber was filled with water to cover only the torso down of the seal, leaving the head above water to discourage swimming. This method was used to monitor the heart rate of the seal while it was resting in the water. If the seal swam then the resting heart rate reading wouldn’t be accurate due to actively swimming. There was no difference in the resting heart rate in water between the ages.

To record the rest air rate, the chamber was drained and monitored with air flow as the seal rested in the chamber. The resting heart rate in air increased as the mass of the seal pup increased. This shows that as age and mass increases so does the metabolic rate. Rather than there being no difference between the mass of the seal and the resting heart rate like seen in water experiment.

Once the pups have fully molted then the difference between heart rate in water compared to on land is not much different. The mass for both is equivalent to air and water. Blubber thickness and stage of molting were the most influential factors in metabolic rate. This being the most influential factor should be well known to scientists, but it’s still a mystery to why the development stage is the way it is. Early development can have many confounding factors that Affect overall energy demands. There is some variation in reproduction history and age. All the pups were born from multiparous mothers allocating the chances of successfully raising the pups. During development the pups showed that calendar age was not as important as the developmental stage for metabolic rate.

For more information, check out the original scientific paper:

Pearson, L. E., Weitzner, E. L., Tomanek, L., & Liwanag, H. E. M. (2022). Metabolic cost of thermoregulation decreases after the molt in developing Weddell seal pups. Journal of Experimental Biology, 225 (6): jeb242773. https://doi.org/10.1242/jeb.242773 

Summary: Long time ago in a land far away from the coast of Maine a mountain range rose from the earth’s crust the himalayas were born, millions of years later this has caused a bit of an identity crisis for these two dolphins from the Platanistidae family that inhabit these south asian rivers.

For more information, check out the original scientific paper:

Braulik, Gill T. et al. (2022) Taxonomic Revision of the South Asian River Dolphins (Platanista): Indus and Ganges River Dolphins Are Separate Species. Marine Mammal Science. 37:1022-1059. https://doi.org/10.1111/mms.12801

Have you ever wondered why whales have scarring on their tails? Are they from boat propellers? Or, maybe from predatory animal attacks? Researchers have been looking into these observations for years. Enrico Corsi is one of those researchers who has used his expertise to determine the origins of the scarring. Corsi and his team observed photos of tails from Cascadia Research Collective’s collaborative photo-identification catalogs for humpback, blue, and gray whales. These photos are from the west coast of the United States of America between the years 1980 to 2017. They examined the location of the scarring, the number of marks on the animal, and how intense the scarring was from the attack. The scientists labeled predatory scarring on these whales as three or more parallel lines on the fluke. There is more scarring on the flukes than in other parts of their bodies because these whales use their flukes as a defense mechanism from killer whales. What Corsi is studying is how the differences in rake marks determine the hunting behavior of killer whales.

The biggest difference in the amount of scarred and mutilated tails in these three species (gray, blue, humpback) is that gray whales nearly double the amount of scarred whales compared to the other two species. Killer whales have scarred 42% of the gray whales that the researchers identified. Whereas, 20% of blue whales and 19% of humpback whales were scarred respectively.

Another difference that they discovered between the whales was where the scarring was located on the fluke. Humpback and gray whales tended to have more scarring on the trailing edge, the portion of the tail that concaves. Meanwhile, blue whales had a higher proportion of scarring on the leading edge, the portion closest to their body, of their tail. It has been proven in previous studies, that scarring on the trailing edge is due to the humpback and gray whales fighting back against the killer whale. The rake marks on the leading edge found in blue whales are caused by the blue whale’s flight-only response toward being attacked.

The findings are indicative that killer whales have evolved a species-specific attack approach. This is because they adopted a different way to hunt due to gray and humpback whales having the instinct to fight back, while blue whales instinctually flee from their predators. This study was only from one portion of the United States. More research needs to be done in order to understand how and when this evolution took place, and what the future holds for other species of whales.

For more information, check out the original scientific paper:

Corsi, E., Calambokidis, J., Flynn, K. R., & Steiger, G. H. (2022). Killer whale predatory scarring on mysticetes: A comparison of rake marks among blue, humpback, and gray whales in the eastern North Pacific. Marine Mammal Science, 38( 1), 223-234.

Orcas are highly social animals, and one can often find them in familial groups, no matter where on the planet you are. Most studies on orca social behavior is conducted in more temperate areas, such as Alaska or British Columbia, so not as much is known about populations in the tropics. However, a study published in February 2020 by Judith Denkinger and others sought to shed some light on the subject.

In the study, researchers used opportunistic sightings from around the Galápagos Archipelago from 1991-2017 to analyze the occurrence of killer whales and look at their social networks. This was done by taking the total number of 627 photos across 91 sightings and looking at the whales’ dorsal and tail fins, saddle patches, and eyepatches, as well as any nicks, cuts, or scars that could be used as identifiers with a computer algorithm used to find matches. When they found a whale that appeared in more than three photos, it was labeled with a number 0001-0067. From these photos they determined groups based off of which whales were seen around each other the most.

Almost half of the orcas spotted in the photos were deemed “non-local”, as they did not appear nearly as often, or were never re-sighted from year to year, though 18 individuals were deemed “local”. The groups were mostly pairs or triads, but two sightings of 15 animals did occur, and sightings of 7+ made up about 12% of the total sightings. Calves were mainly seen in triads or larger groups, with very few groups that were just mother-calf. Interestingly, male/male bonds were frequent, reflecting those of bottlenose dolphins, which is unusual in higher latitudes.

The researchers theorized that the overall patterns of the Galápagos orcas more closely reflect that of “transient” killer whales of more temperate populations. (Transient whales in Alaska and British Columbia typically travel more, live farther from shore, have a more varied diet, and live in smaller groups.) Whales in the Galápagos seem to follow this pattern, possibly because smaller groups tend to have higher energy efficiency, and the small groups will join into larger pods to take down larger prey, including multiple sightings of groups hunting baleen whales such as sperm whales and the Bryde’s whale. They still follow the typical matrilineal associations, but the ever-fluctuating warm and cold seasons seem to have an effect of the fluctuation on group size, unlike their more northern counterparts that have a more stable environment. The researchers deemed this social fluctuation “fission-fusion” and note that since all of their data came from opportunistic photos, it may have skewed the identification of certain individuals.

For more information, check out the original scientific paper:

Denkinger, J, Alarcon, D, Espinosa, B, et al. (2020) Social structure of killer whales (Orcinus orca) in a variable low-latitude environment, the Galápagos Archipelago. Mar Mam Sci. 36:774-785.

It’s no secret that plastic is overtaking our beautiful earth. The amount of plastic in our oceans is projected to reach 250 million metric tons by 2025. The implications of these plastics on marine mammals are unknown and the research is limited due to multiple constraints to data collection. When trying to conduct this research researchers face ethical, legal, and logistical roadblocks.

You may be thinking, where do microplastics come from? These small particles of plastic are broken down from industrial processes and discarded commercial goods. At this point, it seems almost impossible to avoid the use of plastics day to day. Even the most cautious consumer can unknowingly contribute to the dispersal of plastic into the oceans. More and more scientists are motivated to answer how this will affect the magnificent creatures of the oceans.

Beluga whales are iconic toothed whales and found in abundant numbers in the western Canadian Arctic. This species is an important traditional food to the native people of Northern Alaska and Western Canada. Each year the whales are hunted and harvested by the native groups creating a unique opportunity for researchers. In collaboration with the Inuvialuit Settlement Region the community harvested whales are used to collect samples for measurement of environmental pollutants as well as other health parameters. Researchers worked with the community of Tuktoyaktuk to investigate the presence and degree of potential contamination by microplastics in the local beluga population.

A recent study observed a total of eight captured and deceased beluga whales that were harvested by the indigenous people of Western Canada. The researchers examined the stomachs, intestines, and feces of each animal and found evidence of plastic in every whale sampled. More than eight types of plastic polymers were present in the samples, with polyester being the most prominent. The size of the plastics and plastic type are important indicators for the potential toxicity plastic microfibers have. These plastics have also been found in seawater and multiple fish species around the world. In another study arctic cod stomachs were examined and microplastics were found, proving that whale prey are ingesting plastics. It’s important to realize that whales are not deliberately ingesting these plastics, it is assumed that they are passed by the ingestion of prey.

The implications for impacts on mammal health are mere hypotheses in these early stages of research. There’s no denying that plastic is impacting our environment. The fate of marine mammals is in your hands. Will you think of the whales next time you grab a single-use plastic?

For more information, check out the original scientific paper:

Moore, R.C. et al. (2020) Microplastics in beluga whales (Delphinapterus leucas) from the Eastern Beaufort Sea, Marine Pollution Bulletin, Volume 150: 0025-326. https://www.sciencedirect.com/science/article/pii/S0025326X19308793

“There she blows!” This was what you wanted to hear if you were a New England whaler in the 19th to early 20th century, especially if it was a North Atlantic right whale. The North Atlantic Right Whale has historically been classified as the “right whale” to hunt because they are rich in whale oil, slow swimmers, and these whales float when dead. Nowadays, it is illegal to hunt North Atlantic Right Whales, which are critically endangered with only around 421 individuals remaining. However, the species remains threatened by risk of fisheries entanglements and ship strikes.

The North Atlantic right whale feeds on krill and small fish near the surface by swimming with their mouths open and straining huge amounts of water through their baleen. This foraging behavior places them at particular risk of entanglement. The biggest culprit of large whale entanglements are the vertical end lines of lobster traps that suspend in the water column connecting a chain of lobster traps on the seafloor to a buoy at the surface. Entanglement can result in mortalities and serious sublethal impacts to North Atlantic right whales that inhibit the ability of their population to recover. NMFS has calculated Potential Biological Removal (PBR) for North Atlantic right whales at less than one animal can be killed each year due to human activity, yet the death of about 3.25 North Atlantic Right Whales each year are attributed to interactions with the lobster industry.

The population of North Atlantic Right Whales is more fragile than ever, and any possible recovery must begin with a large alteration in the number of vertical end lines to reduce entanglement risk. The most effective method would be to eliminate endlines completely during right whale migration through a time/area closure. However, time/area closures are especially unattractive to lobster fishermen because they believe a reduction in fishing time means a reduction in lobsters landed.

Conveniently, in New England, the Right Whale’s migration season corresponds with the low season in terms of landings per trap for lobster fishermen. Scientists Hannah J. Myers and Michael J. Moore recently validated that time/area closure would allow lobsters that otherwise would have been caught during the closure period to increase in size and contribute to the reproductive cycle to grow the total stock year after year. So for lobster fishery and right whale population alike, time/area closures can facilitate sustainability and growth for both populations.

Both scientists also suggest additional bycatch reduction methods that permanently eliminate the presence of endlines and further reduce risk of entanglement. The suggested methods are acoustic-release ropeless fishing that triggers an airbag to rise with an endline only during retrieval, and grappling by having no endline at all and retrieving groundlines with a specialized hook. These direct endline elimination methods along with time/area closures could finally facilitate an increased rate of growth for North Atlantic Right Whales. This will simultaneously allow growth of American lobster populations, and corresponding sustainability and success for the U.S. lobster industry.

For more information and data, check out the original scientific paper:

Moore, M., Myers, H et al. (2020). Reducing effort in the U.S. American lobster (Homarus americanus) fishery to prevent North Atlantic right whale (Eubalaena glacialis) entanglements may support higher profits and long-term sustainability. Marine Policy 118:104017.

Have you ever missed a part of a conversation and wished you could hear better? Or simply wished your senses were improved, like some type of super-hero, like superman, flash, or one of the avengers? Well according to recent studies done by marine scientists Northern Elephant Seal’s don’t have that problem!

These massive deep diving Marine mammals ranging from 800-5000 pounds depending on age and sex, they are found in the eastern and central part of the northern pacific range of the ocean and have an incredible ability to hear unlike other mammals and here is why. Recent research is suggesting that Elephant seals have super hearing. Scientists believe this to be due to the Elephant Seal’s ossicles which are small bones in the middle ear of the animal. Research suggests they do not use air when moving sound vibrations from the middle ear to the inner ear when hearing such as other mammals like humans. Scientists then looked deep in the ear of Elephant seals with the dissection of specimens that had expired from natural causes. They found that instead of air surrounding the ossicles it was fluid. The bones are held in fluid within the inner ear and will vibrate when listening to sound around it.

These mechanisms greatly improve the Elephant Seal’s ability to hear under water as they dive so deep, because of this adaptation they hear higher frequencies then most. This is advantageous for hearing prey species as well as communication between other members of the species. This new discovery is an exciting and interesting look into the constantly improving and changing information in the Marine sciences world. So careful what you say next time you are swimming of the coast of Cali! You never know who OR what is listening!

For more information, check out the original scientific article:

Smodlaka, H etal.(2019) A novel understanding of Phocidae hearing adaptations through a study of northern elephant seal (Mirounga angustirostris). Ear Anatomy and Histology. Anatomical Record 302:1605-1614.

We as humans are all big fans of animals especially seeing them interact with humans. Many people however view animals being trained for human pleasure to be abusive and not ethical. However, researcher Jay Sweeney conducted research to study the interactions between humans and dolphins to answer the question of what are the possible benefits to this type of behavior?

During the 1970s, there were two major breakthroughs both in interaction with animals and the medical aspect. The first being that the training of these marine mammals changed from a more formal and more strict structure to a more diverse and dramatic behavior which included trainers in the water with the mammals for a more personal interaction between dolphin and trainer. These interactions included physical behaviors and a calmer interactive behavior at the surface of the water. Trainer and veterinarians used a teamwork approach to help stabilize the animals under medical examinations. This led to the focus on disease prevention and the examination of the animal’s current state of health. This allowed for trainers to invest more time with the animals which allows a true positive relationship of trust between the two.

Within the 1990s, the relationship between the marine mammals and their trainers were the focal point as well as the priority of the daily interactions that took place at public display facilities specifically for cetaceans. During this time the use of reinforcers to promote training became more common. The primary reinforcements often consisted of food (fish) however, there also happened to be secondary reinforcers which were often toys and or expressions of excitement by the trainers. With the participation of interactive activities allowed for more time spent with the animals as compared to repetitive show activities.

Now onto our more recent decade the 2000s. Researcher Jay Sweeney recorded that cetacean reproduction within the animals being trained under certain conditions, had a 30% fatality rate in the first month of early growth of newborns. Reason as to why there was such mortality is due to the fear of handling the newborns from the veterinaries. In later years, at Dolphin Quest there was a decision made to implement 4 regulations that would make a better handling of the newborns. After considering these regulations, there was also a consistent observation that showed mom and baby cetaceans are always touching each other. This allowed for a social context which is necessary for future social conditioning. It is known that newborns love to be touched and also love to touch a member of their same species which includes their trainers. Trainers quickly sprung to action and took the initiative to connect within the dolphin mom and newborn social aspects by creating a barrier of trust between mother, baby and trainer. While it may be hard in captivity to see animal benefits, with the use of dolphin/human interaction it shows the resultant in in developing the quality and longevity of life and wellness for these animals as well as actually taking the time and look deeper into what is actually happening behind the scenes and understand that in some areas this could be helpful and less harmful in certain ways.

For more information, check out the original scientific paper:

Sweeney, J. (2020) Genesis and benefits of human/dolphin interactions leading to dolphin interaction programs: Personal observations from 1969 to 2020. Aquatic Mammals 46:418-428.

Killer Whales are apex predators at the top of the food chain. They are known to have very diverse diets feeding on prey of all sizes from small fish to large whales. As scientists have studied their broad diet more closely, they have learned different local populations or ecotypes have different dietary preferences. These prey preferences are culturally transmitted within matrilineal social units. North Pacific killer whales are divided into two ecotypes: “residents” that feed mostly on fish travel in maternally related stable social units, and “transients” that feed mostly on marine mammals and travel in smaller less structured social groups.

Scientists have developed a non-invasive approach to analyzing killer whale diets using stable isotope analysis. Stable isotopes are atoms of the same element that have an equal number or protons and unequal number of neutrons giving them different atomic weights. Isotopes are present everywhere in the world, in the food we eat, the water we drink, and the air we breath. By measuring the different ratios of isotopes in tissue or bone, we can identify what, when and where the killer whale ate.

Skin samples of killer whales were collected in 2009 – 2018 in the Bering Sea. Both Nitrogen 15 and Carbon 14 were measured in resident and transient killer whales off the coast of eastern Russia. Evidence suggests transient killer whales feed on one trophic level higher than resident killer whales. This is important to differentiate because of the killer whales role in the food chain. Top predators have a major impact on controlling and maintaining a healthy ocean ecosystem. Without the ocean’s top predators there to control growth, many other species would see a dramatic population increase, thus having a cascading effect on the ecosystem.  The diet difference between transient and resident killer whales have important implications for conservation management in Russia. This research highlights the need for Russia to take an ecosystem-based approach to fisheries management. Ecosystem-based fisheries management is a holistic approach that recognizes all the interactions within an ecosystem rather than considering a single species or issue in isolation. Population dynamics for these ecotypes are important to stabilize in order to avoid a top down trophic cascade, affecting the populations of lower trophic levels. For example, a population decrease in resident killer whales would reduce the pressure on salmon, while a population decrease in transient killer whales could increase the pressure on salmon due to the decrease in salmon-eating predators. This evidence emphasizes the importance of co-managing these populations based on their dietary specializations in order to properly assess their role in marine ecosystems.

Killer whales inhabit all oceans around the world therefore, it would be ecologically beneficial for all fisheries to consider adopting a ecosystem-based approach to fisheries management. It is important to understand not only how the ocean’s many complex interactions function now, but how they may change in the future due to anthropogenic stressors in order to maintain the balance and functioning of the ocean ecosystem.

For further information, check out the original scientific paper:

Borisova EA, Filatova OA, Fedutin ID, Tiunov AV, Shpak OV, Hoyt E. Ecotype and geographical variation in carbon and nitrogen stable isotope values in western North Pacific killer whales (Orcinus orca). Mar Mam Sci. 2020;36:925–938. https://doi.org/10.1111/mms.12688

It has been known for many years that Killer Whales, also known as Orcas, travel and hunt in packs called pods. These pods are similar to wolf packs, except that the boss is the oldest female, sometimes called the matriarch. Orcas are very social creatures, as they spend most of their life in a group, but even they need to branch out and meet new whales every now and again! A group of scientists recently conducted a study on killer whales native to Alaska, to see how social activity was affected by different groups coming together. What they found was that when the orcas were around groups from different pods, they were much more social, not taking part in normal activities like feeding or hunting. This was even more apparent when pods that were not seen in the larger group very often showed up, as all of the whales seemed to want to be social with the newcomers to get to know them better.

First off, the scientists had to determine how many whales were present. They did this through photo identification and biopsies to determine genetic heritage. The photo identification involves identifying individuals through their size, markings or scars, and any other specific characteristics of each whale. Biopsies were also taken from the whales, which involves taking material which can be tested for genetics and DNA. This also helped identify rarely sighted pods, which were pods that were seen at less than 5% of the recorded interactions, which came out to 12 pods, with 15 pods ranking as frequently seen pods (more than 5% of interactions).

Activities the whale took part in were separated into four categories: socializing, foraging , traveling and resting . These were each defined for the researchers by previous studies in the field. These activities were timed and were averaged to look at the overall scope of the whale’s interactions. What the researchers found was that the larger the group of whales, the less likely they were to engage in foraging activities, and the more likely they were to engage in social activities. Also, if rarely sighted pods were present, the amount of time spent on social activity was much higher since the whales were trying to bond with the newer whales to the group. The orcas were seen to be much more vocal during these social activities as well, even mimicking vocal patterns of other pods! This study showed that whales are more like people than we thought, building communities and making friends along the way.

For more information, check out the original scientific article:

Olsen, D.W. et al (2020) Social behavior increases in multipod aggregations of southern Alaska resident killer whales (Orcinus orca). Marine Mammal Science 36(4):1150-1159.

Over the past several years, the Pacific Northwest has witnessed the return of the Guadalupe fur seal, a species that is listed as threatened under the US Endangered Species Act and was once thought to be extinct. This seal species once inhabited the Pacific coast of North America from Mexico to British Columbia. This range shrank drastically as the species was hunted for its fur until its presumed extinction in the 1800s. Since then, the first sighting of Guadalupe fur seal individuals was reported in at Isla Guadalupe in 1928, followed by another sighting in 1949. The GFS population then grew steadily and is currently estimated to be about 20,000 individuals.

This was revealed by as study done by Erin D’Agnese et al. The presence of GFS individuals was indicated by sightings and strandings on the coast of Oregon and Washington. The scientists conducting this study monitored and collected data from stranded GFS individuals from 2005 to 2016. They recorded a total of 169 strandings and did postmortem exams on 93 individuals over this period. They found the main causes of death to be emaciation, trauma, and infectious disease. They found that most of this trauma was related to commercial fishing in the area, as some of the stranded seals were tangled in fishing gear. Most of the infectious disease related deaths were caused by the parasytes Sarcocystis neurona, Toxoplasma gondii, and gastrointestinal helminths, which are parasitic worms that infect the digestive tract of seals and other animals. The data also show an annual increase in GFS strandings in the summer. This suggests that the seals are migrating to the Pacific northwest from the coast of Mexico, and they are likely following migratory prey species such as squid and anchovies. While the fact that dead seals are being found on the coast of the Pacific Northwest does seem grim, it still indicates that these seals are finally returning to their historic habitat.

This return and resurgence of the GFS is due in part to conservation efforts carried out in the US and Mexico, as the GFS is protected by law in both of these countries. This, along with the rebounds of other marine mammal species over the years, goes to show how effective conservation efforts can be. These findings also indicate how important it is that we continue and improve these conservation efforts. With several of these GFS deaths being related to fishing and other human interactions, it is crucial that we work to adjust fishing methods in order to reduce entanglements and other unnatural causes of deaths. While we have made great progress in preserving our marine ecosystem, we need to continue that progress and avoid reversing it.

For more information, check out the original scientific paper:

D’Agnese, E. et al. (2020) Reemergence of Guadalupe fur seals in the U.S. Pacific Northwest:The epidemiology of stranding events during 2005–2016. Marine Mammal Science 36: 828-845.

Humans use clapping as a way of celebrating or showing appreciation, but what would gray seals use clapping for? Could it be for reproduction, social cues, defense? Sounds are a crucial part of marine life, but non-vocal behaviors are important to observe as well.

Video footage shows male gray seals using their paw-like forelimbs to create a snap-like clapping sound underwater. The sound lasts for less than 1 second and can reach frequencies over 10 kHz! The forelimbs of the seal adduct until the palms are ventral to the chest when the clap occurs. The forelimbs then separate and retract until the palms are near the abdomen before returning to their original positions.

Other video footage suggests that the clapping is a social interaction between seals. This suggestion is because of observations of a male and a female gray seal swimming together and the interaction occurring after the male claps. The video observation shows the female swimming off and the male clapping after her leaving; the male seal received a response clap from another individual in the area. Shortly after this response clap the female swam back to the male. The male seal pursued the female and attempted to bite her hind limb and chases her away. After the pursuit the male then claps for a final time.

So, is the clapping to show fitness to the females? It could be. Is the clapping being used for defense? It could be, but this could also be to ward off competitors in the area.

These clap sounds have also been recorded previously but were interpreted as knock-like vocalizations resembling a walrus. The knock-like sounds have the same short duration, high maximum frequency, and occur in small numbers. The knock sounds were likely misidentified non vocal claps, implying that gray seals use underwater clapping as some sort of signal or communication method. More observations and studies need to be completed to know the exact reasoning, but for now we just have the likely theories of showing off fitness, defense, and/or warding off competitors.

There is not sufficient data yet to confirm or deny if clapping occurs in other marine mammals, but this specific signal is common in other marine mammals. For example, harbor seals slap their pectoral flippers, knock-like vocalizations in walruses, and gunshot sounds by right whales. These variations among species are likely to stand out from one another. Although more observations are necessary to completely understand why the gray seals are clapping underwater, we do know it is not for the same reasons we clap as humans, but hey it’s nice to know humans and gray seals do a daily behavior the same way even if it’s for different reasons!

For more information and to see the pictures of the claps, check out this publication:

Hocking, David P. et al (2020). Percussive underwater signaling in wild gray seals, Marine Mammal Science, 36(2), 728-732.

“We’re going to the aquarium today!” is probably one of the most exciting things we heard as children as we hopped in the car bright and early to take a family trip to see the dolphins and the seals. For many of us, this is where our recognition and appreciation of these animals first started and continued to grow with us throughout the years. But where has this recognition gone? Why aren’t we taking our children to the aquarium anymore? Why has appreciation for our neighbors under the sea declined in recent years?

Researchers indicate that this lack of knowledge about marine mammals could possibly be due to our ever-changing world. Increased urbanization and technological advancements towards the internet and social media play a part in people not wanting to go outside when they can see an augmented reality form of outside from their screens.

But what does increased screen usage have to do with the livelihoods of marine mammals? Well, one of the most evident ways we can see a clear connection between these can be observed through the frequent occurrence of strandings. On the east coast of the United States alone, there are approximately 1,000 strandings that occur each year. This, of course, is a small number compared to the 356,000km of coastline in the entire world, where each and every kilometer was home to at least one stranded marine mammal. North America is fortunate enough to at least have some established facilities to rehabilitate these animals for a period of time, but many other countries lack the basic knowledge and interest to have any sort of rescue team or aquarium in place.

In order to get more people to be conscious of, curious about, and take part in lowering harmful impacts on our oceans, we have to facilitate the method that initially generates interest, resulting in some stage of curiosity, and, ultimately, to an understanding of our impacts and what we have to do to scale them back. Personal experience drives passion. Once you see something with your own eyes, you develop a connection that a screen cannot replicate. When people become exposed to a dolphin or a seal in real life, the respect and appreciation for them increases drastically, like it suddenly hits them that this is a real, live animal in front of them. All that is needed is that initial spark of a connection, followed by continued and developed public engagement, for appreciation to be brought back to marine mammals.

So, next time you’re thinking of an activity to do on your day off, consider taking a trip to the aquarium. You never know the lasting impact one experience could leave.

For further information, please visit the original article below:

Nightingale, J. (2020) A key to a positive future for Earth and its oceans. Aquatic Mammals 46:237-239

Wolves, lions, elephants, bees, and gorillas. How are these species related? They live in packs, herds, prides, hives, and troops. These charismatic animals live in communities and work together with other individuals in their groups. Living in large groups has many advantages like protection against predators and greater ease in predation and foraging. There is another species that also has a social structure and is extremely reliant on interaction with others, the killer whale.

The resident killer whale is found only in the northern Pacific Ocean and exclusively feeds on salmon. The term “resident” refers to a population of killer whales that remain in inland or nearby coastal waters. Resident killer whales are often found in larger pods than other populations of killer whales with pod sizes ranging from five to forty individuals.

Killer whales have complex social structures called matrilines. A matriline is a group of killer whales that are connected by maternal descent, like a female with her offspring and sometimes their offspring. Male and female offspring remain in their matriline for life. Males will only leave for a short time to mate with an individual of another pod and then return to their matriline. A matriline is very stable and individuals in the group have very strong bonds with each other. It is common for related matrilines to travel together and form a pod.

One possible reason for resident killer whales living in groups is to help forage for fish. The size of the group is critical to foraging success because a group that is too large can increase competition for food sources and decrease the amount of food each individual can eat. This is very confusing because it is common for large multipod aggregations to occur and can exceed 150 killer whales. Researchers have found that important functions like resting and foraging significantly decrease when multipod aggregations occur. Those functions are further decreased when multipod aggregations include pods that are usually distant from others and thus rarely sighted.

So, what’s the purpose of these large multipod events if it isn’t to help forage for prey? Social interactions are increased and vocal activity is very high in these aggregations which leads scientists to believe that these events serve a social purpose to the resident killer whale. Multipod aggregations may help to reinforce social bonds between other matrilines and pods, and provide opportunities for mating. These events may also provide vital opportunities for juveniles to learn social, mating, and reproductive skills.

The resident killer whale is an intelligent, long-lived, gregarious species which clearly has dynamic and complex social behaviors. However, these behaviors are not fully understood and further research is needed to better define the role and function of their behavior.

For more information, check out the original scientific paper:

Olsen, D. et al. (2020) Social behavior increases in multipod aggregation of southern Alaska resident killer whales (Orcinus orca). Marine Mammal Science 36: 1150-1159.

Off the coast of South Carolina, dolphins and humans interact all the time, and they’re a large part of tourism in the area. Scientists have been investigated how human interaction affect dolphins and their behavior. A new study investigates how plastic pollution may be starting to affect dolphins as well. Researchers F.N. Battaglia, B.A. Beckingham, and W.E. McFee, looked at several different stranded Common Bottlenose dolphins off the South Carolina coast to see if microplastics (MP’s) have made their way into the ‘diet’ of larger marine organisms.

MP’s are grouped into different categories based on how they look, and how they’re made up. Most commonly, secondary MP’s, those that’ve been changed by chemical or mechanical processes, were found in the animals. Each dolphin that was analyzed was found with MP’s in their GI tract (gastrointestinal tract). The most common type of MP’s the researchers found were white / clear pieces.

Dolphins have three stomach cavities, the fore stomach, fundic and pyloric. The forestomach was analyzed on its own and the fundic and pyloric cavities were analyzed together. One other section that they looked at was an intestinal subsample, which was a portion of the intestines. When they first started this study, they predicted a correlation between size and the amount of MP’s found within the individual. The research showed that the only correlation between MP’s abundance and the animal were “the number of MP’s and the mass of the contents in the intestinal subsample” (Battaglia et al. 2020). Their original hypothesis was incorrection, however it may guide future research.

It is unknown how the MP’s have gotten into the GI tracts of larger marine organisms, such as these dolphins, but the most plausible explanation is trophic transfer. Trophic transfer is the transfer of energy and materials through the food web. If a tiny little phytoplankton is filled up with MP’s and a filter feeding fish comes by to eat the plankton, the fish now has MP’s in its system. This continues on, and on, through the food web and may be the reason that MP’s were found in the dolphins sampled.

Plastics have been found in many marine organisms, such as the stomach of stranded whales, however MP’s have slowly been found in more marine organisms, such as these dolphins.  As humans continue to pollute the water, it puts more marine organisms at risk for consuming plastic, which in turn could cause us to consume MP’s as we share a food source with dolphins. The researchers of this study do warn that it may not represent that population as a whole since the samples are just a snapshot in time right before the animal dies, but it does show that MP’s have made their way up the food chain and it’s uncertain how it will continue to affect these large marine mammals.

For more information, check out the original paper:

Battagila, F.M. et al. (2020) First report from North America of microplastics in the gastrointestinal tract of stranded bottlenose dolphins (Tursiops truncatus). Marine Pollution Bulletin 160:111677. https://doi.org/10.1016/j.marpolbul.2020.111677

Polar bears have always been a beloved animal and keeping them safe has been a mission many have undertaken and vowed to uphold. Climate change on our planet has led to the loss of sea ice which polar bears utilize for hunting, traveling, and mating. Mothers also utilize sea ice as dens while they care for their young through the winter months. Due to the importance of these dens, many locations were identified and recorded in the 1973 Agreement on the Conservation of Polar Bears and are now critical habitats to protect.

In this study, Katie R.N. Florko and colleagues collected information from sources on polar bear maternity denning including data from traditional ecological knowledge (TEK) studies, peer-reviewed literature, government reports, and some data from unpublished reports. They then created a den map using a geographic information system (GIS) database in ArcGIS^R 10.3 (ESRI Inc., Redlands, CA, USA), a system which aids in working with maps and geographic information. The data was then available as either map point locations, map polygon data (location of denning area), descriptive point data, and/or descriptive polygon. Map data points were then geo-referenced in the GIS and descriptive data points were interpreted. Data was then scanned onto JPEG images and geo-referenced onto a North American map to project data in the Canada Lambert Conformal Conic coordinate system.

The results from the study yielded location data from 64 different sources, locating 1593 den points and 430 denning areas. Most of the coastal regions within the Canadian Arctic had dens, though uniform dispersal of dens was not the case, with a lack of dens in Nunavik, Nunatsiavut, and the western Canadian High-Arctic. Some dens were also located on pack-ice in the Beaufort Sea and land-fast ice in the Canadian Arctic Archipelago. Because of the constant relocations of dens due to human disturbances and climate change, this study goes to show how important it is to monitor polar bears and where their dens are so we can protect them and their habitat.

If you want to learn more about this topic, check out the original scientific article:

Florko, K.R.N., et al. (2020) Polar Bear Denning Distribution in the Canadian Arctic. Polar Biology 43:617–621. doi:https://doi.org/10.1007/s00300-020-02657-8

Climate change is one of the most talked-about topics in today’s society, and it is a known fact that climate change is not good. However, recent studies are revealing that climate change may benefit certain types of animals.

Pacific Gray Whales migrate annually from lower latitudes in the winter months to higher latitudes in the summer months. However, one group of Gray Whales stay up north. A previous study noticed that these whales typically weigh less, which in turn affects the reproductive rates of females. It was discovered that there is a positive correlation between the length of the previous season’s amount of ice and calf production.

In a paper recently published, the relationship between environmental conditions and Northbound Pacific Gray Whales is explored. Using data collected from 23 years of visual surveys a shocking conclusion was made. But first, the not-so-shocking discovery that environmental conditions during the early phase of the Gray Whale’s gestation period are important. The data shows that years of substantial ice cover in the feeding grounds of gray whales will then negatively affect the number of calves born the following year. This is because the lack of food resources causes female Gray Whales to avoid pregnancy, not carry a pregnancy to term, and even prevent the female from ovulating. This means that for the Pacific Gray Whale, it is more favorable to live in an environment where ice is minimal. Which also means that climate change will benefit this species.

Climate change is causing the ice in the Arctic to melt earlier, which means that the ice-free season will increase. This allows for more nutrients to flow into the feeding grounds of gray whales, causing the whales to reproduce. Some other species that will benefit from climate change are bowhead whales and other baleen whales. Data collected on bowhead whales shows that they too benefit from a longer ice-free season.

For more information, check out the original scientific paper:

Perryman, W., Joyce, T., Weller, D. & Durban, J. (2020). Environmental factors influencing eastern North Pacific gray whale calf production 1994–2016. Marine Mammal Science.

“Call me Ishmael.” This is the famous opening line of the literary classic, Moby Dick, that brought one species of whale – the sperm whale – to minds of people around the world. Now, this whale is in the minds of scientist as they make new strides in understanding this unique species’ long history.

Sperm whales, Physeter macrocephalus, are the largest species of toothed whale and have the largest brain of any animal. Because of these characteristics, along with their ability to dive in and adapt to extreme conditions, they are known to be very evolutionarily unique. This means that their traits and behaviors cause them to stand out when compared to other similar organisms.

Over the course of a few years, a collaboration of researchers in China worked to map the first chromosome-level genome for a marine mammal using samples from a beached female sperm whale. A chromosome-level genome is a complete set of all the genetic material in an organism. This is similar concept of the well-known Human Genome Project (HGP). Researchers could use this genome to further examine the evolution of marine mammals.

Guangyi Fan and their colleagues used a technique known as whole genome sequencing (WGS), commonly used for these types of studies, to unpack the intriguing evolutionary history of the sperm whale. Using additional analyses, they found that marine mammals have evolved more slowly than terrestrial mammals, identified key characteristics of the sperm whale genome that are the reason the whales can adapt to long and deep diving, and found that the whales showed a rapid decline in population during the Pliocene and Pleistocene transition.

This study and others of the like are important keys to unlocking and understanding many biological questions. For example, the ability to identify what specific parts of the genome are instrumental in determining the sex of an organism. Additionally, as technology continues to develop and genome-wide studies become more readily available, scientists can perform evolutionary studies looking at many different species and their physical and evolutionary relationships.

For more information, check out the original scientific paper:

Fan, G. et al. (2019). The first chromosome‐level genome for a marine mammal as a resource to study ecology and evolution. Molecular Ecology Resources.

Alaska, the last frontier filled with beautiful wildlife and nature. A particularly popular spot for tourists is Glacier Bay National Park, an isolated fjord, filled with an abundance of marine mammals. Many of these mammals are dependent on their hearing to survive, reproduce and communicate. Their ability to communicate is dependent on their ability to hear around them. This might come to a shock to some, but the ocean is not quiet, in fact it is filled with sound from us humans, from the environment, the earth and those that live in it. The noises that we make can minimize the communication space of these animals and in turn affect their ability to survive; this is referred to as masking. In particular, this popular tourist spot with heavy vessel traffic from cruises and private boats is a prime example of how anthropogenic noise can mask marine mammal communication.

In an experiment performed by Gabriele et al. they tested how different levels of varying vessel traffic and nature generated noise affects the call space of two species that reside in the bay, humpback whales and harbor seals. Using real vessel traffic, vocalizations from harbor seals and humpback whales, they compiled these data into a simulation run for three days, each with different ship traffic. The communication noises they used in this experiment were whale songs, whale whups, and seal roars. Then using sound ecology, detection and noise analysis software they created a simulation testing the effect of high, moderate and low vessel traffic. They tested how masking affected the size of communication space for each call.

After running the simulation, results showed that moderate traffic had the greatest effect on the area for communication or communication space. On days with moderate traffic mammals lost around 30-50% of their communication space. Although in the study they also included ambient noise that was wind based, vessel noise still contributed to a loss of more than 70%. Vessel traffic that had synchronized arrivals and departures on high traffic days had less of an effect on the communication than moderate traffic.

Losing communication space for these marine mammals can have many negative effects on their mating and survival. When their vocalizations are masked, the mammals have to compensate by communicating at higher and louder frequencies. In turn this could change the message they’re trying to transmit. Although vessel traffic can affect their communication space there are actions we can take to decrease anthropogenic noise. Using quieter ships, implementing speed limits and synchronizing departures and arrivals can aid in decreasing the noise we create. As humans we have a desire to see nature and explore the last frontier, but we should be conscious of how our desires can impact the world and wildlife around us.

For more information, check out the original scientific paper:

Gabriele, C.M., et al. (2018) Underwater acoustic ecology metrics in an Alaska marine protected area reveal marine mammal communication masking and management alternatives. Frontiers in Marine Science 5:270.

Cuts. Bruises. Strangling. These are all injuries that marine mammals such as gray seals and humpback whales can sustain from human activities like fishing. The National Marine Fisheries Service is mandated by the Marine Mammals Protection Act to report these impacts. But what is a serious injury? The National Marine Fisheries Service created guidelines so that observers on fishing vessels can monitor fishermen so harm to marine mammals doesn’t go unnoticed. An observer and an at-sea monitor work together to make sure that all marine mammals that are caught in nets by accident are documented, not only what species they are but how badly they are hurt. Everything from what specific injuries they have to how they are released (did they swim away quickly or sink like a rock?) is recorded.

Also, how the crew handles the marine mammal and how it’s tangled is written down. This is important to know: can the animal escape if it had more time? Is it totally stuck if humans don’t help it? We’ve all seen pictures and videos of seals caught helplessly in fishing gear, and how long it can take to cut them loose or untangle them without hurting them even worse. Thankfully, this year the records show that most of the marine mammals that were captured were gray seals that were not seriously injured, but there were also some whales that were seriously or fatally injured. We should also pay attention to who is writing the report. How does the National Marine Fisheries Service, an industry with stake in commercial fisheries, write their reports without bias seeping in?

Some of these mammals are already endangered. For example, the right whale is in danger of becoming extinct because of entangling problems with fishing gear close to where they forage. If fishing continues in the same way without changing, these beautiful, historic animals have a very slim shot at survival. This death can throw off a whole ecosystem if an important predator like a dolphin or a whale is eliminated. The report showed that small cetaceans are being killed by what humans use to fish, but doesn’t even begin to show how that radiates through the community. Perhaps more pressure needs to be placed on these agencies to reduce harm to marine mammals caught in nets.

For more information, check out the original report:

Waring, G. T., Josephson, E., Wenzel, F., & Lyssikatos, M. (2019). Serious Injury Determinations for Small Cetaceans and Pinnipeds Caught in Commercial Fisheries off the Northeast US Coast, 2012. Northeast Fisheries Science Center.

We’ve all become familiar with the devastating photos of polar bears struggling on sinking pieces of floating ice in the Arctic. This has become the poster board for melting ice caps, so it’s no surprise that increasing global temperatures are negatively affecting the landscape for polar bears. What most people may not know is that these rapid changes in climate are also affecting the main food source of these predators; ringed seal pups.

Ringed seals tend to have alternating years of high reproductive rates, with many new births, followed by years with a low amount of new pups being born. These years with low production of pups are in years with late ice breakup. When the ice takes longer to break up, there is less light penetration through the water, making the water overall less nutritious. This also makes it harder for mature seals to come up to the surface. Without this broken up substrate, the seals don’t have a place for giving birth, nursing, and shedding old fur.  In years of low productivity the polar bears, who normally feed on the pups of ringed seals on this substrate, have to alter their prey preference.

Scientist Jody Reimer conducted research to study how polar bears altered their diet in years with less seal pups. She looked at survival rates, reproductive rates and effects of predation on the population of ringed seals in the arctic. Her goal was to test if polar bears would choose to consume a different life stage in ringed seals in years of low productivity of pups, their usually primary choice. She also looked at how this predation in years with low productivity would affect the population.

Her results showed that years with smaller populations of pups led the polar bears to feed more on mature seals. This change in life stage of their prey actually proved to reduce the growth rate of the population. On the bright side, less predation on pups allowed more pups to survive into the next year. This is due to the change in behavior of the polar bears. With less pups available on the ice substrate, they tend to seek out larger, older seals on the packed ice. Besides the negative effect on the growth rate of the ringed seal population, this also comes with its own energy costs and risks that come with seeking out stronger, more experienced prey types.

It is important that we continue to study the effects of climate change on these arctic species whose environment is greatly changing, possibly faster than the animals can adapt to. Learning how these animals are adapting to changes in the environment can help us predict their survival in future years, as well as how their relationships with their prey species will be affected throughout this process. The more we learn about how our changing world is negatively affecting the species and environment around us, the more crucial it is that we push for changes in our society that are more sustainable and environmentally-friendly.

For more information, check out the original scientific paper:

Reimer, J et al. (2019) Evidence of intraspecific prey switching: stage-structured predation of polar bears on ringed seals. Oecologia 189: 133-148.

The dolphins of Florida Bay have learned to muck it up when it comes to finding new ways to get a full meal. The end result: a flying buffet of mullet to fill the gullet.

A newly described feeding strategy by only the Southern Florida Bay dolphins further reveals the intricacy of teamwork that bottlenose dolphins are capable of. This strategy, called “Mud Ring Feeding”, had only been observed occasionally until Laura Engleby and Jessica Powell underwent a four year observational study to further understand this fascinating example of teamwork.

Engleby and Powell define mud ring feeding as “a cooperative foraging strategy in which one dolphin creates a ring of mud around a school of mullet (a broad group of fish species) and dolphin group members capture the fish mid-flight as the fish leap out of the mud ring and into the air”.

Sounds easy right? Turns out that there is much more to it than meets the eye, and a lot of strategy and skill is required to successfully feed on the flying fish. First, the eldest or most experienced dolphin forms a “J” using its tail to stir up the sediment on the ocean floor. Next, the rest of the dolphin pod (group) herds the fish into the curve of this “J” shape of stirred up mud. The eldest dolphin then closes the circle with stirred up sediment and thrusts its tail powerfully inside the ring towards the other dolphins who are waiting mouths agape at the edge of the ring. The fish who are frightened by the low visibility of the mud and the powerful pressure of the tail thrust, leap out of the water predictably towards the waiting dolphins.

The further research of this remarkable technique by Engleby and Powell reveals that these groups average at only 3-4 individuals per feeding and that each dolphin can get up to 3 fish each mud ring. Each ring only takes about 5 and half seconds to complete and an average of 11 rings are created on each hunting trip. This add adds up to a lot of mullet for each dolphin in a relatively short amount of hunting time.

Engleby and Powell have discovered that the eldest dolphins have the highest rate of success when they form the actual mud ring. Younger dolphins have been observed watching their elders and trying their own mud rings, yet they are often unsuccessful and need much more practice.

Not only is it an incredible feat to see this teamwork in action, but thanks to Engleby and Powell, we now also know that this flashy style to get food is actually very efficient and more than just for show.

For more information, check out the original scientific paper:

Engleby, L. K., and J. R. Powell. (2019).Detailed observations and mechanisms of mud ring feeding by common bottlenose dolphins (Tursiops truncatus truncatus) in Florida Bay, Florida, USA. Marine Mammal Science 35(3): 1162-1172.

Northern elephant seals are typically known for their large elephant trunk-like noses and being the longest and deepest diving pinnipeds. The study “A Novel Understanding of Phocidae Hearing Adaptations Through a Study of Northern Elephant Seal (Mirounga angustirostris) Ear Anatomy and Histology” by Hrvoje Smodlaka, et. al. found that there is something else that is unique about this species. They have a submucosal cavernous sinus, basically a sack filled with fluid, that surrounds the ossicles in their middle ear and those ossicles are much larger than other phocids’. Ossicles are very tiny bones inside the ear that vibrate when the sound waves hit the ear drum. There are three ossicles; the incus, the malleus, and the stapes. The ear is essentially split into two parts. The part closest to the outside world, the middle ear, is filled with air and the part closest to the brain, the inner ear, is filled with fluid. In most mammals, these ossicles are surrounded by air and they concentrate the vibrations of the sound waves so that less is reflected as it travels to the inner ear. This is called the “air-dependent” impedance transformer mechanism.

In this study, the researchers dissected the inner ear of seven northern elephant seal pups that died of natural causes from the Marine Mammal Care Center in California. They took measurements of the ossicles, the tympanic membrane (eardrum), the stapes, and the cochlear nerve. The eardrum is also a part of the “air-dependent” impedance transformer mechanism. There is a number value that can be associated with this mechanism that is found by multiplying the ratio of the of the eardrum to the stapes by the ratio of the malleus to the incus. The value for the human ear is 18:1, but they found that for northern elephant seals it was only 10:1. This suggests that they do not use air when transferring sound from the middle ear to the inner ear.

The researchers looked deeper and found that the ossicles were surrounded by a submucosal cavernous sinus, and that they vibrated in this fluid. This fluid-dependent impedance mechanism has also been found in teleost fish and odontocete whales. Since northern elephant seals dive so deep for such long periods of time, they use hearing as their primary sense. The fluid impedance matching mechanism enhances their ability to hear underwater and the large ossicles allow them to hear higher frequencies than most other phocids.

For more information, check out the original scientific paper:

Smodlaka, H et al. (2019) A Novel Understanding of Phocidae Hearing Adaptations Through a Study of Northern Elephant Seal (Mirounga angustirostris) Ear Anatomy and Histology. Anatomical Record 302:1605-1614.

Blue whales are the largest known animals to ever exist. Yes, you read that right, the largest animals ever still live today, although they are on the endangered species list. Despite their gigantic size, blue whales eat mainly small shrimp-like creatures called krill that measure an average of only 2 inches in length.

Have you ever heard the saying “An elephant never forgets”? A recent study has found evidence to suggest that a blue whale also never forgets, at least not when it comes to finding food.

The study was developed by scientists to test the “Green Wave Hypothesis”. The “Green Wave Hypothesis” is the idea that animals, specifically herbivores, have long-term memories of where and when they can find abundant food sources. These types of studies have been done on several terrestrial species, but this is the first attempt at testing the hypothesis on a marine mammal.

This study used information collected from temporary radio tags that were placed on 60 blue whales during the 15 year span from 1994-2008. The tags sent signals which tracked whale migration from the coast of Baja Mexico all the way up to British Columbia. They also used satellite data to estimate algae blooms (which is the primary food source for krill).

They ended up finding patterns that suggest blue whales do have memories which last for decades! Specifically, blue whales seemed to go to areas with high algae concentrations and low interannual variability.

This new information about the life of blue whales may have important implications for the management of this endangered species in the future and help explain the effects climate change and human interaction may have on these animals.

While no studies have been done yet to show the effects climate change might have on blue whales’ migration, the authors of this paper think that climate change could potentially alter the locations of algae blooms, making the blue whales’ ability to remember, not helpful. They hypothesize that changes in ocean temperature, currents, and/or light exposure, caused by climate change, could alter the sizes and locations of algae blooms. This makes sense because algae photosynthesis (the process of turning sunlight and nutrients into energy) is dependent on temperature and light exposure.

For more information, check out the original scientific paper:

Abrahms, B., Hazen, E.L., Aikens, E.O., Savoca, M.S., Goldbogen, J.A., Bograd, S.J., Jacox, M.G., Irvine, L.M., Palacios, D.M., Mate, B.R. (2019) Memory and resource tracking drive blue whale migrations. PNAS. 116(12) 5582-5587.

When picturing beluga whales, what do you imagine? They’re cute and they’re all white, right? How complex can they really be? As natives to the Arctic, this species can sometimes be hard to study, but recently, scientists have begun to reveal some of their best kept secrets. One of these secrets concerns their interpersonal relationships with other members of their pod. In the wild, it has been seen that male belugas interact more with other males than females do with other females or males. This finding has led researchers to ask two questions: When does this behavior develop and why?

Researchers Lauren Mazikowski and Heather Hill from St. Mary’s University in Texas worked to understand this by placing 19 individual beluga whales into two different facilities. The whales varied in age from one to five years old and also in gender with a total of 6 males and 13 females. The first facility, Marineland of Canada, housed 15 of the whales and the second, Seaworld San Antonio, housed the other 4 whales.

Perhaps the most interesting thing about beluga whales that they found lied in their social dynamics. Like other toothed whales, the beluga pods generally consist of both males and females living together. However, a key difference separated the belugas from other whales. The captive juveniles interacted with the adults normally, but, from an early age began to show early signs of gender and age specific preferences. The unusual thing was that only the juvenile males showed these preferences. Although they appeared to favor other juvenile males, they were also often seen with adult males. Meanwhile, the juvenile females showed little to no preference at all for either sex.

With the question of when this behavior develops answered, the question of why still remains. This question, it turns out, is much harder to answer. One theory for this gender related favoritism lies in the dynamics observed in adults. The male-male bond seen in the wild is important to beluga whales, as it seems to reduce the amount of fighting that happens within a pod. This suggests that male juvenile belugas choose to spend more time with other males of their age to learn these social skills necessary to keep peace within the pods. While it remains a mystery why females do not have as strong of a bond with others of the same gender it is thought that competition and aggression are not as prevalent in female-female or female-male interactions.

Although this study offered a lot of insight into beluga whale dynamics, there is still much for researchers to uncover still. What was determined, however, is that both in the wild and in captivity, young male belugas formed stronger, lasting bonds with others of the same sex that young females did not display.

For more information, check out the original scientific paper:

Mazikowski, Lauren, et al. (2018). Young Belugas (Delphinapterus leucas) Exhibit Sex-Specific Social Affiliations. Aquatic Mammals. 44(5): 500-505.

You’ve heard of Bigfoot, the large-footed cryptid to roam the forests of the Pacific Northwest. Now wrap your heads around this one: Melon-Headed Whales. With a seemingly made-up name, not quite as catchy as Bigfoot, these animals hold a story similar to the cryptid mentioned above. Impressively, in this era of mass information, they are one of the few whales to maintain an elusive existence. Most information about Melon-Headed Whales comes from Hawaiian waters. Still, beyond that, data over food habits or diving behavior are scarce. They live across warm waters in the tropics and subtropics, mainly Hawaii and South Africa. Just like their name, these whales have ‘big heads’ cause by an enlarged melon or area of fat in their forehead, that is used for echolocation or communication.

Experts like Kristi West and her team of researchers concentrated on the diet and diving behavior of these whales as a way to decipher the secret lives of Melon-Headed Whales. Now hopefully, we all know that animals can be susceptible to their environment. As our world continues to change with oceans warming, seasons shifting, and climates cooling, it is our responsibility to help animals impacted by these changes. Scientists’ research on diet and diving behavior and how it may be affected by future environmental changes revolves around the whales’ ability to search and forage for food.

Researchers studied what exactly whales ate by examining stomach contents collected from strandings in 1985, 2009, and 2017 off the coast of Hawaii and South Africa. Strandings are when whales get marooned on land, usually due to human factors or undetermined causes. Studying the diet by looking at the food inside stranded whales stomachs may sound gross, but it’s a crucial part of their work to decipher what’s inside whales’ stomachs. This work involves identifying the different animals inside their stomachs and, for their diving behavior, tagging three live whales with depth-transmitting satellite tags – like a GoPro, but for whales.

These fancy GoPros delivered data showing a preference for diving during dawn and dusk to grab the most common food found amongst 11 whales stomachs – cephalopods. Diving deeper during the night helps whales capture more squids and octopi. Yet, during the day, swimming behavior is near the surface for eating active and small fish. This diving preference is not only for feeding but may also be a result of high human activity during the day vs. the night.

Like the Great Wall of China with its 30 million stone steps, the research done by West and her team is only a small stepping stone in the future investigation of Melon-Headed Whales. This research may not be as exciting to some as say, finding Bigfoot, but the fact that we’re just now learning more about these whales is absolutely monumental. Once previous myths of the sea with bare information lingering around them, now Melon-Headed Whales are stepping, or swimming, forward into the future of scientific research.

For more information, check out the original scientific paper:

West, Kristi et al. (2018) Stomach contents and diel diving behavior of melon-headed whales (Peponocephala electra) in Hawaiian waters. Marine Mammal Science. 34: 1082-1096.

Keystone species. Ever heard of them? Well, those cute furry, aquatic mammals that hold hands and swim in the ocean, known as sea otters, are important keystone species in their ecosystem. These organisms provide important ecological services to their ecosystem, that most ecosystems could not do without changing dramatically. So, what sea otters eat is important, since that can affect the food web of this beloved animal. These adorable water creatures are actually top predators and eat a myriad of different food. These food choices depend on where the otter is living, location of food, seasonality and food availability. Quite the little seafood connoisseurs. Sea otters will eat urchins, bivalves, crabs, snails and more. They sure aren’t one to turn down a meal. No matter how many legs it has.

But first, let’s dig into the history of one specific population of sea otters: the Washington State northern sea otter population. From the mid 1700’s to the beginning of the twentieth century, when the fur trade was hip and happening, sea otter pelts would be used for coats and other fashion related uses. This greatly reduced sea otter populations and led to the complete loss of the northern sea otter in Washington. So, what do you do when you nearly wipe out a population? You bring in some NEW sea otters from Alaska! The Alaskan otters were brought in from 1969-1970, bred with the remaining Washington population and numbers have increased ever since. Because of this new, hybrid population of Alaskan/Washington sea otters, previous range and food selection for Washington State sea otters changed, since the old population dynamics changed.

Since northern sea otters in Washington State are listed as state endangered, it’s essential to monitor the population. To better understand this species and its foraging ecology, scientists decided to study what they eat and how they eat. Luckily, sea otters eat their prey near the shore and above water, so watching them is easy and important data is gathered. In a study by Hale et al., the authors wanted to see if the population was having any negative population effects because of the increase in sea otter numbers over the past few years, especially in heavily occupied sea otter areas. If this was the case, there would be increased fighting for food or difficulty finding food, which leads to increased foraging, lower energy, and an increased variety of food choices.

The authors found that the more otters there were, there more there was a variety in prey. However, this didn’t necessarily represent overgrowth in the population. It shows that sea otters have the ability to choose different food sources when needed. They also found that where the otters lived, led to diversity in food choice. By understanding these foraging behaviors, management plans can be implemented to continue conservation of this lovable species, the sea otter. With ongoing population monitoring and an increase in commercial fishing regulations, the population could continue to grow.

For more information, check out the original scientific paper:

Hale, J et al. (2019) Influence of occupation history and habitat on Washington sea otter diet. Mar Mam Sci. 35: 1369-1395.

The North Atlantic Ocean is home to one of the most charismatic species, which also has quite a talent. Male fin whales, Balaenoptera physalus, are observed to sing to either attract a mate or to compete with other males for a mate. Their singing is one of the strongest known sounds that whales can make, having a frequency of 16-40 hertz. The songs that Fin whales create are able to be heard more than 600 miles away.

Scientists Christopher Clark, George Gagnon and Adam Frankel found a relationship between the whales’ swimming speed, song duration, and mating season which resonates with impacting noise that covers their own songs.  Through data collected from the US Navy’s marine mammal monitoring program, which uses a hydrophone to collect sound, they were able to open up a world that not many know about. Living above water, we often fall negligent to understanding all of the sounds that happen underwater. From shipping vessels to military sonar to species communication, the singing of whales is just a fragment of what goes on underneath.

How exactly are songs, swimming speed, and mating related? These scientists found that Fin whales would stop singing loudly when swimming at a faster speed and instead would mostly sing at a higher volume while swimming at slower speed. Fin whales were seen to be seasonal singers, where they would sing with a seasonal peak from September to February. This connects perfectly to their mating season, which is observed to be between the months of November to January. When finding a mate, the female fin whale will often judge the males as if they were on an episode of American idol; where their singing ability and physical fitness play major roles in finding a mate.

Why is this something we should be studying? Well, a major threat that marine mammals face are noises created by humans. These noises come from circumstances such like shipping vessels, military sonar, and offshore drilling. Clark and his team sat through and analysed years of data to come to the conclusion that the noises created by humans are plausibly impacting Fin whales in a way that disturbs their singing patterns and reproductive strategies. Think as if you were trying to communicate with your partner in a romantic way, except each time you were to talk, a loud alarm would go off which you had no control over. Sadly, this is what it is like for many species who try to communicate with each other.

For more information on the songs of Fin Whales, check out this publication:

Clark, C. W., Gagnon, G. J., & Frankel, A. S. (2019). Fin whale singing decreases with increased swimming speed. Royal Society Open Science, 6(6), 1-13.

Are you emotional and enjoy being alone? Then BuzzFeed might tell you that your marine mammal type is the blue whale! Don’t get down on yourself, you can look to the bright side—you have actually lucked out by being named as this species!

All jokes aside, blue whales (Balaenoptera musculus), are an incredibly amazing marine mammal. Blue whales are the largest animal to have ever lived on Earth, as well as one of the loudest. Even though they are considered to be one of the noisiest, we unfortunately do not have the ability to hear them because their calls and songs are much lower than our hearing thresholds. Blue whales are also known to be solitary, but in a recently published paper by Schall et al., blue whale trios were observed and studied.

Much about blue whales is still unknown, specifically pertaining to their migration patterns and breeding habitats. Like many other mysticetes, also known as baleen whales, male blue whales produce songs and vocalizations as a way to attract a female mate. (Fun fact! Baleen whales have modified “teeth” that allow them to filter their smaller prey that usually consists of plankton). Interestingly enough, it was recently discovered that blue whales not only create songs, but also calls. Referred to as the D-call, both male and female blue whales can create them. These D-calls have been observed to be produced in various social contexts, specifically when a group of two blue whales come into contact with a third blue whale. D-calls are noteworthy because they are defined as non-song vocalizations and have been observed in almost all blue whale populations.

In this interesting report, the authors studied three blue whale trio encounters. They aimed to explore similarities in their display behavior, focusing in on vocalization characteristics and the potential functionality of their calls. In order to collect their data, scientists relied on passive acoustic and visual observations. Passive acoustic observations consisted of underwater microphone recordings and visual observations consisted of photo and video recordings. Trio behavior was documented by using the GPS position of the observer, the time it occurred, and through visual observations at the surface of the water. Visual observations were recorded using both videos and photos. One trio was observed between Chiloe Island and the Chilean continent, and the other two trios were observed in the St. Lawrence estuary off of Canada.

Overall, the scientists were able to come to some fascinating conclusions. From their data, they suggest that D-calls may be more of social call then a reproductive call. This is actually very exciting because whales are quite understudied and little is known about their calls when not in reproductive contexts. They also suggested that females may produce D-calls as a way to signal their understandings of others calls. This could also be used to ensure that pairs do not become separated. Most importantly, these scientists were able to discover that D-calls play a role in encoding information for specific behavioral contexts.

For more information, check out the original scientific paper:

Schall, E. et al. (2019) Visual and passive acoustic observations of blue whale trios from distinct populations. Mar Mam Sci. https://doi.org/10.1111/mms.12643

Just like us, whales love fast food. A quick bite from a fisherman’s line is the perfect one stop shop. Killer whales and sperm whales are prone to taking fish from commercial long lines. These lines are deep sea fishing lines that have a hundred and sometimes even thousands of baited hooks on a single line. This leads to whales diving for already caught fish (depredation) and often causing injury from the fishing gear in the process. These encounters are not only negatively affecting the whales, but also the fisheries. Inaccurate stock assessments and damage to equipment negatively affect fisherman’s stocks and profit. To learn more about these interactions, scientist Jared R. Towers et. al attached satellite-linked location and dive-profile tags on both killer and sperm whales in South Georgia. These tags allow the scientists to track both the whales location and depth of their dives.

Naturally these whales target squid and octopi to feed. The fish most targeted on the long lines are the patagonian toothfish. This fish has a high lipid (fat) content and is a preferred meal for killer and sperm whales. Patagonian toothfish swim at 500-2500m depth. Most interactions with the longlines were during gear retrieval. When the fishermen retrieve their gear, the whales would take deeper and longer depredating dives than their natural foraging dives, to get to the toothfish caught on the line.

Taking unnaturally deep dives can cause physiological damage to the whales from the dives alone.  Some argue that the depredating dives are more beneficial to the whale population than detrimental. These interactions allow for an easily accessed, supple food source.  Some hypothesize that the depredating dives were due to increased competition for nutrient resources. From the data the scientists collected in the study they found that the toothfish were mostly supplemental feeding, they could survive without this resource.

There have been efforts to help decrease the frequency of depredation from killer and sperm whales. One attempt to decrease the encounters between the whales from depredating dives was to set the lines at deeper depths, but the data show whales diving to whatever depth the gear was set. This may indicate that the whales may be capable of diving to the seafloor. Steps have also been made to modify gear and to delay taking the gear up when whales are present. There is a lot to be learned about these whales and depredating dives. What we do know about these interactions is that both fishermen and killer and sperm whales are being negatively impacted by these interactions. Efforts need to be made to limit these interactions, and learn more on why they continue to occur.

For more information, check out the original scientific paper:

Towers, J et al. (2019). Movements and dive behaviour of a toothfish-depredating killer and sperm whale. ICES Journal of Marine Science. 76(1): 298–311.

Human use of the ocean affects marine mammals in a major way. Confused by loud noises, whales, dolphins and porpoises often sustain traumatic injuries and even end up as marine roadkill in shipping lanes. Survivors of these encounters are forced to adapt, which takes valuable energy away from essential activities like feeding and reproduction. Traditionally, these responses have proven difficult to study as marine mammals spend large portions of their time underwater. However, recent advances in technology have allowed researchers to study even the most elusive of species through an ‘eye in the sky’ approach.

Due to their lack of a dorsal fin and small body size, the finless porpoise is poorly visible at the surface. There is very little scientific knowledge of their sociality. Among the local people, they are generally thought to exhibit small group sizes. However, they have relatively large brains similar to those of more socially inclined mammals, suggesting that they do have the capacity for complex social interactions. Using drones, two researchers in Misumi West Port, Ariake Sound, Japan, were able to successfully track the behavioral responses to human disturbances of both single and groups of finless porpoises over the course of a year. They were particularly interested in the social dynamics within groups and how these change in response to encounters with boats.

The researchers found that finless porpoises, which are not generally thought to be strongly socially bonded, engage in social behavior to mitigate adverse effects of close encounters with boats. They reduce the stress associated with these experiences by sticking together and even exhibit affectionate behavior by rubbing their bodies against one another as if they are consoling each other. A common avoidance behavior among marine mammals is to dive in response to a threat, this is thought to be a stress induced instinctual reaction. The time that porpoises stay under water was shown to be reduced in larger groups. This is beneficial because diving costs a lot of energy. By reducing the amount of time they spend diving to avoid boats, more of this energy can then be used to invest in normal activities.

The study of the finless porpoise is important in furthering our understanding of the impacts we are causing in the marine environment and developing new methods to study how this affects marine life. But it’s more than that. Their responses to stress tell an important part in the story of the evolution of the social brain. Under normal, non-threatening circumstances, the finless porpoise is a lone wolf despite having a brain that is capable of complex function. However, under stress it’s as if this function is activated, and the porpoises learn to find strength and comfort in numbers to ensure their wellbeing. Studying their behavior can teach us about the development of social structures in marine mammals, and may even be analogous to better understanding our own.

For more information, check out the original scientific paper:

Morimura, Naruki and Mori, Yusuke (2019). Social Responses of Travelling Finless Porpoises to Boat Traffic Risk in Misumi West Port, Ariake Sound, Japan. PLoS ONE 14(1): e0208754.

Have you ever walked out onto a jetty or a rocky beach somewhere along the coast of California, or possibly even Japan? Did you ever notice how some of the rocks or slabs by the water’s edge may have been chipped or damaged near the sharp edges and ridges? Well, it’s nothing natural! Fuzzy, cuddly sea otters actually use these to help them break open the hard outer shells of some of their prey, mainly mussels found living in coastal waters.

Sea otters only survive in remnants of their original habitat, which spanned from Baja, California, Mexico, around the Pacific Rim through the coast of Japan, and are the only known species of marine mammal to use stone tools. Sometimes they’ll float on their backs and use stones as anvils – an object on which things can be hammered and shaped – to open clams or crabs, but they also use stationary stones or concrete slabs to crack open mussels. These large stones are known as emergent anvils. A group of researchers spent a total of ten years, 2007 – 2017, watching tagged and untagged sea otters’ foraging habits at Bennett Slough Culverts in California. During this period, they concluded that otters often targeted mussels as their preferred meal and only used emergent anvils to consume them.

After close archaeological observation of the emergent anvil stones used by these otters, they discovered that they left distinct damage patterns that were distinguishable from markings human use might leave behind. The sea otters appeared to have a striking preference, only pounding the mussels on points or ridges of the stones, but only from in the water. Michael and Jessica et al. also observed the shell middens – an accumulation of disposed matter – left behind at emergent anvils by the otters at BSC. After analyzing a random selection of these shell fragments, they discovered a very consistent breakage pattern; the right side of the shells appeared to have diagonal cracks running through them. With this discovery, it is exponentially easier to identify mussels broken by otters as compared to other marine mammals or humans. This concept is exceedingly important for archaeologists, as they need to be able to tell the difference between past human behaviors from that left by other animals, such as sea otters.

The scientists that led this study hope that its results will help archaeologists that are working around coastal regions distinguish human and sea otter behaviors when analyzing impacts of marine resource consumption, as well as help identify how far back the use of emergent anvil use in sea otter foraging behavior can be observed. It may also be useful in identifying other possible areas of current and past sea otter residence in a specific coastal area. In addition, this information can help establish the areas that are used most for foraging, that way conservationists can try and protect these locations so that their food sources are not at risk. These kinds of studies up until this point in time have primarily only focused on primates, so more studies such as this will help establish a new and exciting path for the augmenting field of animal archaeology.

For more information, check out the original scientific paper:

Haslam, M. et al (2019). Wild sea otter mussel pounding leaves archaeological traces. Scientific Reports. 9 (1) DOI: 10.1038/s41598-019-39902-y

Mammals, both marine and terrestrial, use acoustics as an important role in their behavior with how they interact with the environment, as well as other animals around them. Roars are performed by male seals and play an important role in both territorial defense and possibly even for female choice. Roar duration and frequency is thought to play a role in how females choose a male. Dominant males have a low frequency and long duration roar, whereas the subordinate males have a high frequency, short duration roar.

In a study performed by Matthews et al., they playback the sounds of different male harbor seals that were residents of California. There were 5 female harbor seals from the Oregon coast aquarium who were subjected to test over two years, with 7 different treatments. Year one used short duration high frequency calls, long duration low frequency calls and then a control water noise for sounds played. Year two used long duration high frequency calls, short duration low frequency calls, the water control, and an added control with sounds synthetically made to have similar duration and frequency to that of a harbor seal roar. Speakers were placed underwater and played for equal durations on different days for all treatments. The piece of data being looked at by the researchers was a response from the females. A “response” is classified as when a seal would approach the speaker. This was shown by cameras that were taking video. Time spent at speaker by a seal was also recorded.

For year one the treatment with the highest approaches on average is long duration low frequency. Year two showed the treatment with the highest response on average was long duration high frequency. There was not a significant difference between the response to long duration low frequency and short duration high frequency in year one. But there was a significant difference between the roar playbacks and the controls. The dominant male roar playback still had the highest average approach. Ultimately  the choice of the female still comes to preference, and there is evidence backing that dominant males have an advantage. Choice is shown by this test because the females all tended to go to one of the treatments more than the others.

What can be looked at now after these results were interpreted? There can possibly be new studies done, like this one, but done in the wild to see if these results will vary any. The most important thing that can be taken from this study is that female seals show a form of choice in what male they mate with, and that it isn’t entirely based on if the male is dominant or not.

For more information, check out the original scientific paper:

Matthews, Leanna et al. (2018) Female harbor seal (Phoca vitulina) behavioral response to playbacks of underwater male acoustic advertisement displays PeerJ 6: 45-47

Imagine that you are a young mother and right in front of you your newborn was murdered. This did happen to a young orca mother.  In a research center in Johnstone Strait, studies a population of orcas living in the area is where this attack happened. The attackers were an adult male orca and his mother. Both of them were the ones who killed the baby orca.

The killing of a newborn by a male is a result of sexual conflict. This attacking is not well observed in marine mammals; however, this attack is different because it is the first time this behavior has been seen in orca. Also, the first time where both the son and mother take part in the attack. The killing of a newborn gains the male a mate (the female) that was not available to him and for the mother she also gains benefits of finding a mate for her son. The killing of a newborn by a male very commonly studies in land mammals. The reason why males perform this killing is that the lactating female goes back to being fertile and can mate again.

Another explanation for this behavior could be environmental stressors. That sad day for both the young mother and baby. At about 10:00 am there was some orca vocalization detecting from a remote hydrophone (a record that place in the water). These vocalizations were strange for the population of orca that lives in the area. Because of the strange vocalization, a team of researchers went out into the field to see what was happening and to find what was the causes of the noises.

When in the location where the strange noises came from observation toke place. The first thing was an adult female and her adult son were traveling behind a young mother, her offspring, and her sister.  New wounds was seen on the young mother’s sister. All orcas are moving west and soon stop once splashing occurs.  Splashing slow down the young mother’s baby was no longer with her. Instead, it now inside the adult males’ mouth, while the young mother tries to help her baby the males’ mother got in between them. It was later seen in a video that the mother made the first move in drowning the baby by grabbing the baby’s’ tail.

This attack happens because of sexual selection. The mother and son attack the young mother because her baby was a newborn and it would be easier for her to switch from lactating to reproduction. This is the best conclusion because the baby orca body was intact. This means it was not food driven. After the attack, both mother and son stop acting aggressive meaning this was not a territory attack. The big picture of this experiment is that this type of behavior can happen again in orcas due to the fact they have a high lactation to pregnancy rate and orcas have some experience of killing small mammals.

For more information, check out the original scientific paper:

Towers, J.R., et. al. (2018) Infanticide in a Mammal-Eating Killer Whale Population. Sci Rep 8: 4366

It’s never easy to cope with the death of a family member or a friend, and the grieving process can look very different for different people. Do you isolate yourself to process the death on your own, or do familial bonds become stronger as individuals lean on each other for support? What happens to these bonds as more and more family members start dying in succession and it seems like there’s nothing you can do to stop it? Scientists were looking to answer these questions in response to a massive mortality event from 1996-2002 of killer whales in the Crozet Islands, South Indian Ocean.

Sociality, or group living, is an ecological strategy that increases individual success. People say there’s strength in numbers and killer whales are no exception. These whales live in matrilineal pods, meaning that the mother is at the center of social systems. The Crozet Islands killer whale population in question has been studied since the 1970s and has been determined to associate in stable groups with limited dispersal. Interactions with illegal fisheries increased when killer whales began taking Patagonian toothfish directly from the fisheries in an act called depredation, which resulted in the fishermen using firearms and explosives on the killer whales. This is considered to be a human-induced additive mortality event, meaning that the deaths are above the naturally occurring threshold as a result of human activity. Scientists were interested in investigating both how the social structure of killer whales was impacted by a human-induced additive mortality event and how social impacts affected the survival of individuals.

The methods used were photo identification paired with social and demographic analyses, although conclusions focused primarily on social analysis. Mean half weight index (HWI) quantifies how often a pair of individuals are seen with each other. Mean HWI and mean sum of associations were calculated over three subperiods: pre-illegal fishing, illegal fishing, and post-illegal fishing.

Both the mean half weight index and sum of associations decreased from the pre-illegal fishing period to the illegal fishing period. The mean HWI continued to decrease post-illegal fishing but the sum of associations returned close to what it was pre-illegal fishing. This means that there was an increased association with individuals from other social groups. This was likely to maintain a functional group size for foraging, but bonds were weak and there was no stable group reassociation.

The results from this study show that a loss of individuals in a particular killer whale social group results in weaker associations between surviving individuals, and that the disruption of social systems as a result of demographic stress can have negative effects for years following an additive mortality event. To put it simply: familial bonds grow weaker following the death of family members in killer whale social groups.

For more information, check out the original scientific paper:

Busson, M., Authier, M., Barbraud, C., Tixier, P., Reisinger, R., Janc, A., & Guinet, C. (2019). Role of sociality in the response of killer whales to an additive mortality event. Proceedings Of The National Academy Of Sciences, 116, 11812-11817. doi: 10.1073/pnas.1817174116

In the media driven world of the 21^rst century, we have all seen the videos of marine litter and its impacts.  The turtles and fish caught in plastic rings or the floating trash islands eating up miles of ocean surface.  There are, however, many hidden impacts of marine litter that don’t make it onto our phone screens.  The impact of marine litter on marine mammals, and how we measure the impacts, were the focus of the scientists, politicians, and speakers that attended the 31rst annual European Cetacean Society Conference workshop in Middelfart, Denmark in 2017.   This workshop focused upon the collective current knowledge of marine litter impacts, the policies and procedures currently in use, and improvements that can be made to increase this knowledge in the future.

This workshop hosted many speakers from both academic and private institutions, as well as government and non-profit organizations.  Cristina Panti discussed this workshop and its outcomes in her paper: Marine litter: One of the major threats for marine mammals. Outcomes from the European Cetacean Society workshop.  This paper discussed the major marine litter impacts, data collection methods, and policies and procedures that are currently used by the organizations and institutes from many different countries.  Her paper also discusses the policies and procedures that were discussed as improvements to increase world knowledge of marine litter and its impact upon marine mammals.  The speakers of this workshop wanted to use their workshop to increase the connectivity of the worlds’ knowledge through networking and harmonized methods of data retrieval, along with increased communication and raised public awareness about marine litter.

There are many things limiting the data we have today.  Current methods, from the speakers attending the workshop, limited data to marine mammal strandings.  Strandings were also tested with very loose procedures, where much data could be missed in microplastic impacts due to large sieve sizes and limited autopsies of the animal’s gastro-intestinal tracts.  The data for the current studies are only shared when papers are written.  These limits are currently putting a strain on public awareness and policies we need to put in place to limit impact.  Moving forward, stranding networks need to perform autopsies on each animal and make sure they filter the entire gastro-intestinal tract of the animal using multiple sieve sizes.  The data from these stranding networks also need to be shared, not just when a paper in written.  This will increase the knowledge of marine litters’ impact upon marine mammals.  Working together to understand this impact is important for the world as we look to preserve and protect the oceans moving forward.

For more information, check out the original scientific paper:

Panti, C., Baini, M., Lusher, A.,Hernandez-Milan, G., Bravo Rebolledo, E.L., Unger, B., Syberg, K., Simmonds, S.P. and Fossi, M.C. (2019) Marine litter: One of the major threats for marine mammals. Outcomes from the European Cetacean Society workshop. Environmental Pollution, 247: 72-79.

Even though the industrial chemicals called polychlorinated biphenyls, better known as PCB’s, were outlawed in the 1970’s, they can still be found in the world around us; recent evidence has made this astonishingly clear. Back in 2016, a male newborn killer whale was found dead on the beaches of Sylt, a German island. It is not common to come upon stranded killer whales, with this stranding marking the ninth since the 1880’s. Due to this, a group of scientists led by Joseph Schnitzler of the Institute for Terrestrial and Aquatic Wildlife Research in Germany, examined the newborn for possible causes of death. After taking body measurements, testing blubber and stomach content, and collecting skin samples, they found some concerning results.

By using characteristics such as coloration, teeth emergence and the fact that the umbilical cord was still present on the male, they aged him at only three days old. PCB concentrations tested from the blubber showed levels much higher than the threshold that would suppress the immune system, and the threshold at which severe reproductive effects would occur. The average level of PCB’s in adult females is currently very high as well, only slightly higher than this newborn. To Schnitzler et al. this meant that the newborn acquired these high concentrations of PCB’s directly from the mother through breastfeeding.

A study conducted in 2018 on PCB levels in killer whales explained that the effects of PCBs on the bodies of killer whales could threaten the future of more than 50% of the world’s killer whale population. Both male and female killer whales ingest these chemicals in the food that they eat, and the PCB’s ‘biomagnify’, or increase, in level as they move up the food chain. Levels of the chemicals in the male orcas continue to increase throughout their lifetime, but female orcas lower their levels during reproductive years as they pass their high levels of PCB’s onto their offspring through breastmilk. Schnitzler et al. explains that the male newborn stranded in 2016 had a poor chance of survival from the start as the milk he was getting from his mother was essentially toxic.

This particular newborn belonged to pods of killer whales in the North Sea near the UK, Denmark and the Netherlands according to DNA testing. This finding makes results even more significant, as that pod of killer whales is comprised of only eight individuals with the last known successful birthing over 19 years ago. If newborn killer whales are not able to reach ages where they can reproduce and grow the killer whale population, the global population could be in danger of crashing. Marine pollutants continue to be a growing threat for killer whales and other marine mammals, especially when they can be passed so readily onto future generations.

For more information, check out the original scientific paper:

Shnitzler, Joseph G. et al. (2019) Supporting evidence for PCB pollution threatening global killer whale population. Aquatic Toxicology 206: 102-104.

We’ve all heard that there are plenty of fish in the sea, but what if fish aren’t the ideal food choice for some of the ocean’s top predators? A study done by Salvador Jorgenson attempts to find out what happens when killer whales and great white sharks clash in a similar niche, and what the consequences of that battle include.

Although a great white shark’s diet consists mostly of fish, other sharks, and rays, they have a particular taste for elephant seal pups before their migration. This is because the pups provide a source of high-calorie meat, perfect for bulking up before a long trip. However, this prey choice is energetically valuable for any predator, which is why killer whales are also competing for this food source. Jorgenson et al. observed this predator-predator-prey relationship by tagging great white sharks with trackers and observing killer whale behavior from high peaks since they are difficult to tag. Over the course of the study, there was only one direct interaction between the two hunters where a great white shark was killed and only partially eaten by a killer whale. This caused sharks to completely disappear from the area surrounding the attack (and the remains) for 8 weeks. Less dramatically, most interactions resulted in the sharks leaving before the whales got close enough to have a physical altercation.

What does all this mean for the sharks? The seals? This antagonistic relationship between the two predators has resulted in displacing the great white shark population, reducing the overall consumption of elephant seal pups. Northern elephant seals are currently undergoing rapid population growth. As noted by Jorgenson, “[a]ny population regulatory effects white sharks, killer whales, and their interactions have on elephant seals could become more significant as elephant seals approach an equilibrium level.” Meaning, it is hard to know what effects this will have on the population of the elephant seals, however, the effect on the sharks is going to be fairly more striking. With less availability to these high-calorie resources, great white sharks are going to be less successful in their natural migratory behaviors. The decrease in great white shark population may also have cascading effects further down the line, so it is important that this study remains active so we can have some warning to when these changes begin to occur.

For more information, check out the original scientific paper:

Jorgensen, S. et al. (2019) Killer whales redistribute white shark foraging pressure on seals. Scientific Reports 9, Article 6153. https://www.nature.com/articles/s41598-019-39356-2

North Atlantic right whales are an endangered species of baleen whales with a range from the Gulf of Maine to Florida. During spring and summer months right whales spend their time off the coasts of Massachusetts and Maine feeding on planktonic species of fish and invertebrates. Due to the status of their population, scientists use acoustic monitoring to learn about their activity and behavior on these feeding grounds. Right whales, just like most marine mammals, use sound to communicate and commonly use an up call or a high amplitude call that can travel distances of over ten miles. It is a very distinct call, therefore clear that a right whale was the one who made the call. A recent study focused more on their winter calving grounds as there is little to no research that has been done to monitor these whales outside of their feeding habitat.

The idea behind this study was to tag whales with suction cups, something that hadn’t been done with right whales. Historically, either stationed hydrophones on buoys or ships have been used. Due to technological advances, this study attached hydrophones directly to the whales. Scientists were able to record the distinct up call as well as a new call that they termed “Paired Grunts”. These new sounds were much different in nature as they were low amplitude short range sounds. On the calving grounds upcalls were recorded at rates between 0-7.4 calls/hour, comparatively, data from their feeding grounds show frequencies between 0-720 calls/hour (Parks et al., 2019).

What the researchers found out from this study is vital to the future of this population. Instead of using the typical acoustic monitoring of upcalls used on foraging grounds, other methods will be needed. The main reasoning for this is not a lack of calls or a lack of whales but instead the nature of the calls. The whales were communicating in close range instead of long distance feeding calls. Due to these findings, typical acoustic monitoring can detect whales, but it is much more difficult and could provide less data or inefficient data. Continued acoustic monitoring is still needed but other methods like visual detection is needed in this area. That being said continued research into what these short range calls mean and why they are being produced could aid humans further in understanding what these whales are doing.

The right whales deserve our continued support for their survival. With an estimate of under 500 right whales out there today they need us more than ever. Anything that can prevent their death or aid in reproduction is super important to these whales. On top of knowing where they are, it may also provide insight into where they are going to be, when they are going to be there and what they are doing. If we know how they communicate we can make further inferences on their life. Knowing where an army is one thing but knowing what they are going to do will win you the war and in this case we are fighting a war against the death of a species, and a keystone one at that.

For more information, check out the original scientific paper:

Parks, Susan E, et al. (2019). North Atlantic Right Whale (Eubalaena glacialis) Acoustic Behavior on the Calving Grounds. The Journal of the Acoustical Society of America. 146: EL15.

You might think that Cape fur seals at a colony in Mossel Bay, South Africa are afraid of the moon if you watched their behavior at night. Night observations are exactly what scientists did in a recent study of the affect of ambient light on the foraging behavior of fur seals. Cape fur seals, like many other seal and sea lion species, haul out on beaches or islands in large numbers to form colonies, but their food source is out in the open ocean so they must voyage out to find food. Unfortunately for them, their main predator, the great white shark, knows this and sits in wait for the perfect opportunity to strike. To get out to open waters and their food sources, the fur seals must swim the gauntlet past their predators so those seals must choose their moment well. They choose not to make that swim when lots of sharks are present and I can’t say I blame them!

The scientists knew from past studies that white sharks are visual hunters, so they need to be able to see their prey to catch it. Following that logic, the sharks shouldn’t be able to catch fur seals in the dark at night, so the study looked at how the fur seals changed their behavior depending on how much light there was. It makes sense then that they found that the fur seals increased their trips off to find food during times with the least predator activity: nighttime. The fur seals ventured out overnight and were back by morning when the light returned. They were also seen to decrease their movement in winter when the sharks were more active and to travel in large groups when they did go out. The interesting part though, was that the scientists found that the fur seals stayed at their colony at night if the moon was glowing bright. Its as if the moon was a big danger sign saying don’t swim now or the sharks will get you!

This study was the first time that the lunar cycle was studied in relation to foraging behavior and that makes it something special in its own right. As if that wasn’t interesting enough, the scientists also compared this study to human effects and things like anthropogenic (human made) light pollution. They said that if there is too much light from anthropogenic sources, then fur seals will have less time to forage as sharks will always be able to see them. The poor fur seals would be under attack from sharks at all hours! Imagine that!

For more information, check out the original scientific paper:

Morse, P., Mole, M. A., Bester, M. N., Johnson, R., Scacco, U., & Gennari, E. (2019). Cape fur seals (Arctocephalus pusillus pusillus) adjust traversing behaviour with lunar conditions in the high white shark (Carcharodon carcharias) density waters of Mossel Bay, South Africa. Marine Ecology Progress Series. 622: 219–230.

On the icy shores of Alaska there are 1,200lb, 10 foot long animals washing up dead and this has gotten more frequent over the past 25 years. These animals are called Steller sea lions and they are found from Alaska down to southern Oregon, they are the northern cousin to the more famous California sea lion. These animals come together in large breeding colonies every spring to reproduce and spend their summers and winters in search of food.

These animals are split into two population groups, the northern range which mostly consists of Alaska (AK). The other population is the North West (NW) US and Canada (near Seattle and Vancouver). In the last 25 years strandings have increased for these large animals. In 1995 there were less than 10 total recorded strandings, where in 2006 there were over 140 total recorded strandings with 120 of these in the NW portion. This number has since declined to as low as 65 individuals in 2011 and is once again on the rise with 95 individuals in 2015. Most of these strandings happen in the summer months and to adult, male sea lions, which are the larger of the sexes and require more energy and food to survive.

The paper “Stranding trends of Steller sea lions Eumetopias jubatus 1990−2015” by Janessa Esquible, Shannon Atkinson, depicts these stranding trends and maps them out. One thing that’s important to point out is that there are a lot more people living on the north west coast of the US then in all of Alaska, which means there are a lot more people to observe strandings in the NW then in AK. So some of this data may appear worse in some areas then it actually is. With that said, this unexplained amount of strandings in both regions are staggering. There have been suggestions that there needs to be an increase in funding in stranding and surveillance networks in these areas as a lot of data is incomplete. This is to better understand why these strandings may keep occurring and how we can prevent them. Steller sea lions are an important link in the marine ecosystem. These strandings could be a sign of greater stress on the overall system, that’s why this research is so important to try and find a cause to find a solution.

For more information, check out the original scientific paper:

Esquible, J and Atkinson, S (2019). Stranding trends of Steller sea lions Eumetopias jubatus 1990−2015. Endangered Species Research. 38: 177–188.

Scientists explore if Weddell Seals are increasing foraging effort and diving behavior in order to support pregnancy.

A marine mammal’s survival and reproductive output relies on the animal’s ability to adapt to changing environments and their efficiency in obtaining resources and energy. Just like pregnancy in humans, it is vital to consume the extra nutrients necessary during pregnancy, in order to ensure that your baby is happy and healthy and carried to full term. In today’s world, it is especially important for seals to carry and conceive as many pups as they can, and to guarantee their survival.

In a study published in November 2018 by Michelle R. Shero et al., researchers collected data measuring the increased foraging efforts of Weddell seals in the Antarctic. They measured the mass, dive duration, dive shapes and the dive activity of pregnant seals vs. non-pregnant seals. They did this by attaching a satellite tags to the fur on adult female seals’ heads, and the data from these tags were transmitted to a satellite system, and analyzed. They summed up the overall foraging efficiency of these animals by calculating an overall time difference spent diving  between pregnant and non-pregnant females.

Once the data were collected, it was seen that twelve females were seen to give birth the following year, while eight did not. This research found that there was no real difference in weight gain between females that were pregnant, versus those that were not. The only difference in weight gain seen was that of fetal mass in pregnant mothers. The study also concluded that pregnant mothers spent more time diving. From this we can assume that while the pregnant seals must be consuming more food, the lack of weight gain is most likely due to all of the food and energy going to the mothers’ pups. In addition, it showed that females descended faster and came to the surface much slower than non-pregnant females and exceeded their normal dive time limits and oxygen stores during the months closer to birth.

Once all of this data were grouped together, it was concluded that pregnant females spent an overall 1.09 more hours per day diving. Which means that they spent 8.9% more of their day diving for food in order to support the extra energy it takes for a successful pregnancy, and to guarantee the health of their pups before and after birth.

For more information, check out the original scientific paper:

Shero, MR et al. (2018) Temporal changes in Weddell seal dive behavior over winter: Are females increasing foraging effort to support gestation? Ecology and Evolution. 8: 11857-11874.

Florida isn’t just a paradise for the retired, but the Florida manatee resides here for the great variety of food, lack of predators, and a refuge area. However, with rising number of vacationers, there has been shown an effect on manatee behavior to boat noises. These beautiful sea cows like to chomp their food and swim around, but with an increase in human activity, their lifestyles may be changed for the worse.

Duke University, Florida State University, The Florida Fish and Wildlife Conservation Commission and Woods Hole Oceanographic Institute monitored the Florida manatees in Charlotte Harbor National Estuary in Florida. These sea cows are typically seen in shallow waters, floating near the surface without a care in the world. But with these lackadaisical manners, these creatures are very susceptible to boat collisions that are most times fatal. Scientists from these groups are trying to figure out how manatees react to boat noises to hope to find a way to reduce moralities of human-induced deaths among manatees.

Eleven female manatees were belted with trackers and acoustic sound tags that would record the location, noises of boats, and the noises that the creatures made, such as chewing. These records were taken during the day when boats were most present and manatees ate and moved around more. Information about the manatee was also taken, such as weight, height, scar patterns, and girth to individualize each of the test subjects. Sounds were recorded until the acoustic devices ran out of space and the belt automatically detached from the manatee and floated to the surface.

What was found was that each individual reacted differently to the boats. Similar to how humans grab food on the go, some manatees continued to eat while they were fleeing from approaching boats. Some manatees did not fear the boats, and stubbornly continued to eat their food. Others only fled when the boat sounded close. Each of these animals behaved in their own way!

It is so important to monitor how manatees behave towards boats. Manatees are the ocean’s lawn mower, where they keep the sea grasses short and healthy. Monitoring these behaviors can help push for conservation efforts for these adorable cows of the oceans! If boats are becoming a problem, then allowing the manatees their own space should be a priority! Plus, humans wouldn’t have to pay for their damages to their boats from collisions. Staying out of feeding and mating areas can help save both manatees lives and humans’ wallets!

For more information, check out the original thesis:

Burke, T. (2019). An Analysis of Boat Noise and its Influence on the Feeding Ecology of the Florida Manatee (Trichechus manatas latirostris). Masters Thesis. Nicholas School of the Environment, Duke University.

Since the dawn of man, the ocean has been a valuable resource, important to cultures all around the world. In recent years, the ocean and its resources have been the subject of many hot topic issues that are incredibly important and relevant to talk about, including pollution, climate change and many others. One ongoing issue that has become increasingly relevant in recent years is the impact that fisheries play on the animals living in the environment in which the fishery operates. In other words, if there was a fishing boat putting nets into an environment with the intention of catching one species of fish, scientists now would be very interested to study how this process might affect the predators that feed on that species or how it might affect the population of a species below the target in the food web.

In southern Brazil, the fisheries present in the waters off the coast play a huge role in the economy. Because of this, continued and stronger efforts to fish the southern Brazilian coast have been implemented, especially in the last two decades. However, according to the data provided by the fisheries operating in the area, even with the increased efforts, there is increasingly less fish being caught. How might this affect the animals preying on these types of fish, being that they are already in competition with the fisheries? In one study conducted by Rodrigo Machado and his colleagues, they sought to discover how one of the top marine predators in the area, the South American sea lion, reacts to change in prey available to them. Fisheries data taken from the last two decades was used to identify the fish that have been in decline as a result of the increased fishing efforts. This information was one piece of the puzzle, but scientists still had to find out what the target prey of the seas lions was.

To do this, they scoured 270 kilometers of beach to search for dead sea lions. Once they found the dead animal, they brought it back to a lab and analyzed its stomach contents to find out they had been eating. The diet-data from sea lions collected in the first 10 years was used as a comparison to how much their diet had changed within the second decade. This is how scientists gauged whether the sea lions’ diet was being affected by the overfishing that was happening. The results of the study showed there was a large overlap between fisheries targets and sea lions preferred prey and that there was an obvious shift in the prey targeted by the sea lions within the second decade.

So what does this research mean? Fisheries hang in a delicate balance with the natural environment. If too much of one type of fish is caught, it can have drastic impacts on the environment. Due to the poor management style of the fisheries operating on the southern Brazilian coast, these negative impacts are beginning to come to light. A shift in one of the top predators diets in the area has started to be recognized, so this begs the question, what unresearched impacts on the food webs around the world are in existence, and how much change can these food webs support?

For more information, check out the original scientific paper:

Machado, R. et al. (2018) Changes in the feeding ecology of South American sea lions on the southern Brazilian coast over the last two decades of excessive fishing exploration. Hydrobiologia Vol. 819 p. 17-37

When more than one predator occupies an environment, they must compete for resource, territory and top of the food chain. This is the case in False Bay, South Africa. Orcas, seven gill and great white sharks have co-existed in this ecosystem for years, but as of 2015, the tides have turned. A new sub-group of killer whales have become specialized shark killers. Not only are they intelligent enough to flip the sharks onto their backs, putting them into tonic (a sleep-like state), they have come to recognize that eating shark meat is highly toxic, due to raised mercury levels. What part isn’t toxic? The liver. The liver makes up approximately 30% of a sharks’ body weight, is free of mercury from filtration and high in fatty lipids and proteins key to an orca’s nutritional requirements. So, the killer whales have become surgical in a sense, able to create an incision along the sharks’ pectoral girdles.

Two orcas have become especially notorious in the case of these shark attacks. Port and Starboard (named after their flaccid dorsal fins) are two rogue males who actively hunt sharks along the coast of South Africa. The causalities found were recorded in a study performed by Engelbrecht, T. M., et.al. in their pursuit to understand why orcas have focused themselves onto sharks. Necropsies performed by the scientist revealed that each shark found deceased, around the same period as when the orcas had spent time in False Bay, had a broken pectoral girdle, as well as distinct tooth impressions made by killer whales on each pectoral fin. These attack wounds indicate that the orcas habitually feed on these sharks, learning how to reduce injury when dealing with them and lowering their energy cost.

The reason why this has become worrisome to researchers, is because sharks play a vital role in their ecosystem. They remove weak, or disease-ridden seals, and other sharks and rays from the environment, promoting overall ocean health. The combined teamwork from orcas and sharks help contain marine mammal populations to a sustainable level, allowing for species even lower on the food chain to thrive or remain at healthy capacities. Further research on the upcoming effects that shark loss will have in South Africa’s coastal environment is needed, as well as what these killer whales are lacking, that is causing them to hunt sharks as a last resort.

For further information, check out the original scientific paper:

Engelbrecht, T. M., A. A. Kock, and M. J. O’Riain. (2019). Running scared: when predators become prey. Ecosphere Naturalist, 10: 1-8. e02531

People go to the grocery store to get their food, usually the closest grocery to their home. You pick out the foods that look the most appetizing to you, making sure it’s within your price range. For the Galapagos sea lion, it’s go-to meal is the 1.5-meter long yellowfin tuna, talk about a filling meal. Would it be crazy for me to say that Galapagos sea lions get their food in a similar way as people do?

The Galapagos sea lion has adapted to the warm temperatures and fluctuation in abundance of prey by getting their food close to home, making sure they don’t get too tired. It’s the same concept as when people grocery shopping, you don’t want to travel far and you also don’t want to spend too much money. The sea lion equivalent to money is their energy. They don’t want to waste it or use it all at once and they want to ensure that the “money” they are spending will be well worth it.

Scientists were curious as to how they achieved this goal in such a rigorous environment. In the research study, Hunting and cooperative foraging behavior of Galapagos sea lion: An attack to large pelagics, Diego R et al. (2019) flew an unmanned aerial vehicle (fancy name for a drone) 20 m above sea level to follow and observe the hunting strategies of male Galapagos sea lions. The study showed that the hunting strategy required work from five or six different males where each male had his own job.

Two sea lions are assigned to be the delivery guys, they swim out into the open ocean in search of a yellowfin tuna school. Once they have their eyes on the prize, they target one or two tuna and chase them back to home base, blocking each of their rapid turns as they try to hopelessly escape. Now, the delivery guys have successfully brought back the yellowfin tuna to shallow waters and through the gates of their home. Next, the gatekeeper steps in and blocks the openings where the tuna could possibly reach their freedom back to open waters. The delivery guys are still at it, trying to deliver the food to its appropriate location, the beach. They reach the shoreline and the tuna only have one place to go, flailing up onto the rocks. As the yellowfin tuna is in its most vulnerable moment, the chef, who is the oldest male and has the most experience, strikes the tuna and viciously rips out the neck. Finally, they feast.

Now you may be wondering, why assemble this entire team if they all have to share the food they get? The answer is simple, by splitting up the work each male saves energy overall. They do less for more. We all have dreams in life and we all want them to come true by doing the least amount of work. So yes, I would say teamwork does make the dream work.

For more information, check out the original scientific paper:

Diego, R et al. (2019) Hunting and cooperative foraging behavior of Galapagos sea lion: An attack to large pelagics. Mar Mam Sci. https://doi-org.prxy4.ursus.maine.edu/10.1111/mms.12646

Remember when you were younger, and lived under the same roof as your sibling(s)? Tensions would arise, and you would pick fights with them. Or if you don’t have siblings, have you heard of this sibling rivalry? At some point, we’ve all probably experienced a conflict in our households or social groups. Hopefully, none of these conflicts left scars like it does for Indo-Pacific bottlenose dolphins. The Shark Bay Dolphin Research Project located in Western Australia documented scars on Indo-Pacific dolphins caused by other dolphins. You may be wondering why one dolphin would attack another, but, just like humans, dolphins interact in social groups—causing competition over mates, relationships, and resources.

Why does it matter?

The scars, called rakes, examined on the dolphins were mostly caused by other dolphins, indicating some sort of conflict. The goal was to figure out what sex the scars were most common, and at what age these fresh scars were appearing, which will help us and the scientists to understand the costs and benefits of living in a social group.

How did they do it?

For over 30 years of research in Australia, scientists from the Shark Bay Dolphin Research Project identified around 1,700 individual dolphins. They distinguished dolphins as individuals, and determined their sex and age. Then, they assessed the freshness of scars, and confirmed what caused it. Photos showed scars caused by other dolphins that are small, shallow and in black parallel lines. However, they also showed scars caused by sharks that are circular, deep, and has fewer lines.

What do the data show and what do they mean?

The Shark Bay Dolphin Research Project discovered that the average healing time for scars was approximately 1.6 years. Also, that 90% of males, who experienced more scars, and 95% of females healed within a year. This significant difference is most likely due to sexual differences in immune response and aggression. In terms of age and sex, the juveniles have a higher rate of scars present, because during this time period there is more competition, especially when males are establishing partners. Once the dolphins reach the age where they start mating (around age 10), they have less scars. At this time, dolphins have established partners, and therefore there is less competition. Scientists can use these discoveries to better understand the costs and benefits of living in social groups, and compare it to other species. Scientists can also uncover the effects of climate change on social living species in the future.

For more information, check out the original scientific paper:

Lee, HH et al. (2019). Every scar has a story: age and sex-specific conflict rates in wild bottlenose dolphins. Behavioral Ecology and Sociobiology 73:63.

Manatees are seen as charismatic mammals, a favorite part of anyone’s trip to Florida. With climate change, we have been seeing more extreme weather events and storms, especially in Florida. However, whenever a storm passes through and water temperatures dip below 68 °F, there is trouble brewing in paradise for our aquatic friends.

In the event of a cold storm, manatees must evacuate the area in search of warmer waters. If warmer waters are not found the effects can be detrimental. At temperatures below 68 °F, manatees suffer from Cold Stress Syndrome (CSS). CSS is just what it sounds like; it begins with hypothermia and leads to the eventual death of the animal. In 2011, 282 manatees in Florida died from Cold Stress Syndrome. For already fragile populations, any decrease in population should cause us alarm. However, 282 manatee deaths is quite significant, as it was 6% of the entire Florida population.

As manatees often have trouble with thermoregulation, extreme weather events often spell trouble for manatees. In an effort to provide background knowledge needed to figure out bigger issues like Cold Stress Syndrome, six scientists specializing in manatees partnered up in order to try to understand more about their thermal regulation. The scientists explained, “To better understand their capabilities to cope with thermal stress, knowledge of a manatee’s thermal state is useful.” In other words, before we can understand how to help manatees, we must first understand why they are so vulnerable to temperature changes.

As measuring temperature would be difficult on a manatee, the scientists decided to measure heat flux. To better understand the idea of a heat flux, just think that a positive heat flux means that heat is going from the skin to the environment, a negative heat flux means the manatee is taking up heat from its surroundings, and a heat flux of 0 is at equilibrium.

Hugh and Buffett, the only scientific-research manatees, were used for the study by securing a heat flux disc against their skin. Their heat flux was measured six times in 41 different spots on the body. Forty-one locations may sound extreme, but scientists were interested in learning about possible ‘thermal windows’. Thermal windows are areas of the body such as the head and appendages, which are believed to be areas of high heat loss.

Once the results were analyzed, thermal windows were evident within the head and appendages. While scientists expected the heat flux to show evidence of thermal windows, the heat flux for winter was quite unexpected. The heat flux in winter was much lower than other seasons, though the manatees were in a temperature-controlled pool year round. This suggests that air temperature plays a role in way manatees thermoregulate. This is likely why manatees must flee to warmer areas to cope with temperature stressors.  While we now know that air temperature plays a role in manatee thermoregulation, it remains uncertain how we can help these vulnerable creatures from CSS.

For more information, check out the original scientific paper:

Nicola, E et al. (2018) Heat flux in manatees: an individual matter and a novel approach to assess and monitor the thermal state of Florida manatees (Trichechus manatus latirostris). Journal of Comparative Physiology B 188(4):717-727.

Experts have quite literally yet to scratch the surface of what we know about humpback whale social behavior. For years, whale enthusiasts have observed this charismatic giant elegantly perform spectacular events at the ocean’s surface. However, humpback whales spend a majority of their lives underwater, leaving a huge gap in what we think we understand about how they play, network, or even persuade a mate.

Imagine trying to know someone’s whole persona after a semester of seeing them sit in the same class as you. You’d probably be surprised by unexpected pieces of their life, or how they conducted themselves around their friends and family.

It was this curiosity that led a group of scientists to conduct a study on humpback whale behavior in the Galera-San Francisco Marine Reserve, located on the northern coast of Ecuador. It was this study that produced the first ever underwater video documentation of humpback whale social interactions from the Ecuadorian coast.

While espionage and eavesdropping on humpback whales for a living sounds pretty incredible, the process was extensive and took a lot of patience. After 91 hours of visual observation from a 24-foot fiberglass boat, researchers collected about 15 hours of acoustic recording and only 2.06 minutes of high-resolution social interaction video.

The team adapted past approach techniques to collect their data, which included protocols that would ensure for the least amount of disturbance and human interaction with the whale subjects. The research vessel cut engines as soon as whales were observed within 100 meters, visual and acoustic recorders were deployed, and it was left up to the whales to naturally come within range of the recording devices. It was an explicit combination of events and luck that allowed for this unique chance to analyze their behavior, and which unfortunately cost researches the opportunity to get acoustic plotters deployed in time for that rare 2-minute clip.

The researchers’ video shows two whales showing off their moves in a synchronous dance. They move simultaneously back-to-back through the water, pectoral fins extended, believed to be a male and female taking part in socio-sexual behavior. A third whale just barely appears below the focal pair, which is assumed to be an outcompeted male whose moves were apparently just not dazzling enough. Other studies suggest the third whale could have been present as a principal escort in this triad. Though scientists could not determine the sexes without uncertainty, the fundamental findings agree with past subsurface observations.

For more information, check out the original scientific paper:

Ona, J., et al. (2019). A giant’s dance: Underwater social and vocal behavior of humpback whales recorded on the northern coast of Ecuador. Aquatic Mammals, 45(4): 456-464.

If you ask Kelly Jaakkola and Kevin Willis, they’ll tell you that that’s an unexpectedly difficult question to answer. These two scientists decided to sit down and apply modern day methods to this age-old question in the field of biology.

Life expectancy is defined by Merriam-Webster as “the average life span of an individual;” however, according to Jaakkola and Willis, averages cannot be applied to this study of bottlenose dolphins because the data aren’t distributed normally. Furthermore, this isn’t the only abnormality with determining life expectancies and survival rates in this case. The three primary equations these two navigate in their analysis paper of the same name, ASR, Age-at-Death, and the Kaplan-Meier, each have their own underlying assumptions and requirements in order to attain proper results. It’s tedious work, and provides only skeletons of what should be a complete picture.

Armed with the most reliable database possible, the Marine Mammal Inventory Report (MMIR) maintained by the U.S. National Marine Fisheries Service (NMFS), Jaakkola and Willis got to work picking through the bones to salvage what data they could. Subjects for which crucial information were missing, such as birth date or death dates, were automatically excluded from the study. After applying such filters, they had a little over 1,300 subjects whose data they could work with; yet, even with a substantial sample size, the final outcomes still weren’t entirely reliable.

So how long do dolphins really live? Well, the Annual Survival Rate method yielded a ballpark average of approximately 91-97% survival rate for dolphins living in zoological care as far back as 1974 and as recent as 2013. The median lifespan using ASR was 17.4 years. Though they grouped the data into four, six-year groups to make things easier to interpret, they did not keep this trend up heading into the second method, Age-at-Death, since it was not necessary. The median lifespan using this method was 21 years for dolphins older than one year of age, a vastly different number than the ASR method yielded. To muddy the waters even more, the Kaplan-Meier method resulted in yet a different median lifespan across the same four, six-year groups used in the ASR analysis, ranging from 9-29.2 years.

Jaakkola and Willis went into extensive detail and employed several methods of analysis of life expectancies and survival rates. Be that as it may, none of these numbers can be considered true representations of these demographics. To take that one step further, comparing these demographics between those in zoological care and wild populations requires comparable data of which there is very little. Given that, it’s quite possible the true average lifespan of a bottlenose dolphin may stay shrouded in mystery forever.

For more information, check out the original scientific paper:

Jaakkola, K. and K. Willis. (2019). How Long Do Dolphins Live? Survival Rates and Life Expectancies for Bottlenose Dolphins in Zoological Facilities vs. Wild Populations. Marine Mammal Science. 35: 1418-1437. https://doi.org/10.1111/mms.12601

Off Santa Catalina Island, California there are free ranging Risso’s dolphins. Some of these dolphins were used in a study that scientists conducted to test hypotheses of whether odontocetes’ feeding rates vary when feeding at different depths and if they regulate their locomotor and diving performance in response to changes in prey distribution and availability. To test this, scientists explored the foraging behavior and kinematics of cephalopod-eating Risso’s dolphins using motion sensing and acoustic recording tags to evaluate foraging performance.

Archival tags were attached to these dolphins. These tags had a suction cup system, which means they released off of the dolphins at sunset, or in some cases, would unintentionally release due to movement. These tags were positively buoyant and would transmit a signal when at the surface. This allowed for tracking and recovery. Stereo acoustic data were also collected, and a subset of 18 tagged dolphins were subject to controlled acoustic playback exposure experiments (or CEE). This allowed scientists to assess whether behavior was a consequence of CEE.

To understand the type of prey that these dolphins were feeding on, scientists used ships and underwater autonomous vehicle (AUV) based hydroacoustic surveys. AUVs allowed individual animals to be observed within scattering features, whereas the ship-based sensors provided a view of entire features. Frequency differencing was used to facilitate coarse taxonomic classification (i.e., fish, squid, or crustacean) while target strength was used as a proxy of length within each taxonomic class. Dolphin’s foraging opportunities were higher close to shore. This was supported by visual observations during tagging in 2013, when market squid were observed at the surface and in the mouths of Risso’s dolphins.

Based on this information, these dolphins were classified as a shallow-water habitat species who forage close to the benthic boundary layer, or seabed. These dolphins were recorded doing deep dives. Generalized linear mixed-effects models indicated that dive kinematics were driven by foraging depth rather than habitat. Bottom-phase duration and the number of attempts to capture prey per dive increased with depth.

The dolphins in this study appear to use several mechanisms to maximize foraging efficiency, depending on their feeding depth. The dolphins varied their diving kinematics and prey quantity when foraging in prey layers with different composition. They foraged throughout the day in shallow and deep-water habitats, attempting to capture prey at depths of up to 488 m. Diving patterns were stereotyped when foraging at particular depths irrespective of the habitat type. They altered their activity for different types of dives in response to metabolic demands, indicating that their foraging tactics were influenced by foraging costs and benefits.

For more information, check out the original scientific paper:

Arranz P, et al. (2019) Diving Behavior and Fine-Scale Kinematics of Free-Ranging Risso’s Dolphins Foraging in Shallow and Deep-Water Habitats. Front. Ecol. Evol. 7:53. doi: 10.3389/fevo.2019.00053

In 2011, Western Australia’s Shark Bay faced a marine heatwave during which temperatures soared to 2-4℃ above average. While this may not seem like much for humans, it caused catastrophic effects to the marine environment. The high water temperatures killed 36% of Shark Bay’s seagrass beds – an important breeding habitat for many fish and invertebrate species. This led to high mortality in these populations. This produced a sort of domino effect that made its way to the bottlenose dolphins – where it wreaked havoc on their survival and reproductive rates. While heat waves like this may not happen too often now, climate change is predicted to increase their frequency as much as 41x by the year 2100.

In a study published in Current Biology, researchers followed the Shark Bay population of dolphins from 2007 – 2017, collecting data on their population numbers, feeding behavior, and reproduction. Since they began their study 5 years before the heat wave occurred, they were able to compare their data from before and after its occurrence. The scientists took photos of each dolphin to individually identify them based on their markings and fin shapes, while also recording their behavior. Their reproductive output was measured by observing whether or not an individual was spotted with a calf. Monitoring the dolphins’ behavior allowed the researchers to categorize the dolphins by their distinct feeding behaviors. Some of these dolphins use an unusual strategy to catch their prey – they carry around pieces of sponge in their mouth when feeding on the ocean floor to protect their noses from sharp corals, rocks, and stingray barbs. The group of dolphins that use this strategy are called “spongers”, and about 12% of the population do this. The researchers compared the survival and reproductive rates of spongers and non-spongers, to see if this technique gives either group an advantage over the other.

The results were less than ideal; the survival of both groups of dolphins declined in the 7-year period following the heat wave, as well as the number of calves born. 

Interestingly, however, the survival of the non-spongers declined by 12%, while the spongers only declined by 6%. The authors believe this is due to the ability of spongers to feed in deeper waters, where there was less damage to seagrass beds. This is as opposed to the non-spongers who were feeding in shallow waters where the bulk of the damage from the heat wave was evident. As for reproduction, both dolphin groups faced a significant decrease in the number of calves born. This means that even sponge-using dolphins are doomed in the face of warming waters.

It is clear from this study that heat waves cause ecosystem-wide damage. With marine heatwaves predicted to become far more likely with the intensification of climate change, this could mean populations of dolphins – as well as many other marine species – are in grave danger.

For more information, check out the original scientific paper:

Wild, S., Krützen, M., Rankin, R. W., Hoppitt, W. J., Gerber, L., & Allen, S. J. (2019). Long-term decline in survival and reproduction of dolphins following a marine heatwave. Current Biology, 29(7).

Have you ever been to a concert? If you answered yes, you know the feeling of being in an environment that is just a little too loud for what we can normally handle. Now imagine being in that kind of environment everyday. That is the life of a Humpback whale living in the soundscape of the Caribbean. The soundscape is the acoustic environment in which an organism lives. This is comprised of geological/physical processes, biological noises made from organisms that live in the habitat, and human made noises. Many marine animals rely on the use of sound in order to communicate, to find their way around the ocean and to find the food they eat.

In this study, Heather Heenehan, a scientist of Integrated Statistics at the Northeast Fisheries Science Center, and a team of other researchers, focused on the acoustic environment of the Caribbean and specifically focused on Humpback whales. In this study, researchers used two different acoustic recording devices to pick up the different frequencies of noises, one picked up the low frequency noises, the other recorded the higher frequency noises.

From the data they collected, there was variation on how often the humpback sounds were picked up due to the different seasons as well as the time of day. Not only did they discover humpback whale songs in the research sites, but they also picked up on minke whale noise, which was found nearly every day; they also recorded ship noises everyday.

One of the biggest contributors to the sound environment of the Caribbean was ships. For a period of two weeks, at all seven locations where sound was recorded, there were recordings of vessel noise. For the majority of the time, there was an overlap of whale song and vessel noise occurring at the same time.

From all the data gathered from this study, researchers were able to conclude that vessel noises in the Caribbean are a considerable contribution to the soundscape. This can impact the ability of these animals  to be able to use sound to communicate with one another. When looking at a map of global shipping transit, vessels pass right through the southern Caribbean islands. These noises created by vessels not only cover up songs created by humpback whales, but also pose a risk of vessel strike. Although the soundscape of the Caribbean is composed of many different elements, vessel noise plays the largest role in it and it’s up to us to try and figure out how to stop this.

For more information, check out the original scientific paper:

Heenehan H, et al. (2019) Caribbean Sea Soundscapes: Monitoring Humpback Whales, Biological Sounds, Geological Events, and Anthropogenic Impacts of Vessel Noise. Front. Mar. Sci. 6:347. doi: 10.3389/fmars.2019.00347

When the average person dives to the bottom of a deep pool it is usually a challenge for them to hold their breath until they reach the surface. Once they break the water’s surface the person will typically take a deep breath, then breathe deeply and rapidly until they are recovered. This will happen to the average person after 30-60 seconds underwater, but what about a dolphin that can hold its breath for an average of 8-10 minutes?

Although dolphins live in water, they are still mammals that breathe air. Just like us they require oxygen and exhale carbon dioxide, but unlike us they breathe through a blow hole. In order to dive deep to find the best food sources, dolphins have developed a number of adaptations to allow them to hold their breath for extended periods of time, such as the ability to reduce their heart rate or their tendency to store oxygen in their blood and muscles instead of in the lungs. Even though they can hold their breath for up to 10 minutes, dolphins must come up for air eventually to exchange built up carbon dioxide for much needed oxygen. This process of recovery determines how long the dolphin must spend at the surface. The longer they spend at the surface, the less time the dolphin can spend underwater finding food.

Researchers at Texas A&M University wanted to know what bottlenose dolphins do to minimize the time they have to spend at the surface after holding their breath for extended periods of time. They did this by training 11 captive dolphins to voluntarily flip belly up underwater, holding their breath, until they were signaled to flip back over and breathe again. As soon as the dolphin flipped back over an instrument was placed over their blowhole that measured the number of breaths they took, the amount of air they were taking in with each breath, and the amount of oxygen that the dolphin was using. After multiple trials at varying length of breath holds they found some interesting new information on dolphin recovery.

As the length of time that the dolphin held its breath increased, the dolphin had to use more oxygen, take deeper breaths, and take breaths more frequently. This is a similar reaction to a person breathing heavily after going for a run. As the dolphin was recovering from the breath hold, they used up less oxygen, took shallower breaths, and took breaths less frequently over time.

This study proved that dolphins actively increase their respiratory effort to decrease time spent recovering at the surface. Just like an oxygen deprived person, they increase the number of breaths they take and the amount of air they take in. However, unlike a human, a 196 kg dolphin requires only 10 breaths (1.2 minutes) to recover completely from a 2.65 minute breath hold. And that isn’t even a challenge for these dolphins. Throughout the study they never even used their full lung capacity.

For more information, check out the original scientific paper:

Fahlman, A., et al. (2019). Ventilation and gas exchange before and after voluntary static surface breath-holds in clinically healthy bottlenose dolphins, Tursiops truncatus. Journal of Experimental Biology, 222:jeb192211.

Imagine swimming in the cold ocean waters, you’re hungry and searching for your next meal. Since you’re a harbor porpoise and eat basically anything, you’re on the lookout for a variety of fish species ranging from Atlantic cod to herring. Out of nowhere, your foraging is halted due to increased noises in your home, the sounds of pile-driving and vessel traffic. According to Booth (2019), several studies have demonstrated that harbor porpoises change their behaviors following exposure to high intensity noises and are detected less.

Harbor porpoises are found throughout the Northern Hemisphere waters and in order to cope with colder waters, harbor porpoises are required to feed regularly due to their lack of fat stores and energy reserves. Their lifestyle includes relatively short periods of feasting and famine, so noise disturbance can greatly alter their ability to survive. Harbor porpoises use high frequency “clicks” to forage and previous studies researching acoustics have determined they vocalize less, meaning it’s highly likely their foraging stops in response to noise.

Booth wanted to analyze previously published studies to assess the effectiveness of harbor porpoise foraging, the energetic costs related to foraging and how these inform their vulnerability to noise disturbance. Previous studies included acoustic monitoring to track vocalization and foraging behavior from tagged porpoises in the Baltic sea. They studied porpoise diet and energy budgets through analyzing the stomach contents of 339 porpoises who died from a stranding (swimming or floating to shore) or bycatch (accidental catch of a non-targeted species) event.

The results of Booth’s analysis found that under four potential scenarios looking at their diet and energy obtained, only in the worst-case scenario of a single species diet (feeding on only Cod, only herring, etc.) did the porpoise capture a small portion of their daily energy requirement. This means the porpoises were most vulnerable to disturbance via missed foraging opportunities. The key finding from this paper is that harbor porpoises have a wide variety of food sources with a broad range of energy intake and are able to be successful in their environment unless in their worst case scenario mentioned above.

It’s very important to minimize disturbance during harbor porpoise foraging, but this paper gives some evidence that harbor porpoises have some elasticity in recovering from lost foraging opportunities. More knowledge and research are needed about prey abundance and distribution and metabolic costs to further understand harbor porpoise ecology and susceptibility to disturbance.

For more information on harbor porpoise vulnerability to disturbance, read the paper below:

Booth, C. (2019). Food for thought: Harbor porpoise foraging behavior and diet inform vulnerability to disturbance. Marine Mammal Science. https://doi.org/10.1111/mms.12632

Animals are known to take precautionary measures to protect their children, I am sure that any parent reading this can relate. In a species of whales known as Southern right whales, it has been seen that they use evasive methods of communication with their children or calves. In a paper published in the Journal of Experimental Biology, scientist Mia L. K. Nielsen and her partners observed these whales and concluded that they used a process called acoustic crypsis in order to keep calls between mother and calf to a minimum, possibly to stay discreet when predators such as killer whales are around.

Southern right whales are known to migrate from Antarctica for feeding, to Australia for breeding. This study was done in Flinders Bay, Western Australia, when the whales were breeding. Nielsen showed that these mother-calf pairs of whales during migration to their breeding grounds, stayed close to the shore (5-10m deep water), even though there is a greater chance to be stranded on shore and lower visibility with all the breaking waves near shore. There must be a worthy benefit for the whales if they are lessening communication and moving in a semi-dangerous part of the ocean, right?

Nielsen assumed the benefit was keeping the calf alive from predators such as killer whales, who are known to be able to eavesdrop on the calls made by these whales. Southern right whales have a relatively low fecundity, that is they are only able to give birth every 3-4 years, so mothers are very protective over their young.

In this experiment done by Nielsen, they were able to put tags that measured pressure, sounds, and activity levels on 9 mothers, but were unable to tag any calves as the tags would fall off due to constant body contact between the mother and her calf. A hydrophone called a SoundTrap, which measures noises underwater was deployed for 24 hours to estimate the levels of background noise near the whales.

Nielsen concluded that Southern right whales keep to communicating through body contact most of the time, and used calls very infrequently, primarily to keep in contact when close to one another. It was also seen that when the whales did use calls to communicate, it was below the background noise level.

So what does this mean? It is hypothesized that their calls are quieter than the surrounding noisy wave-breaking area, in order to use the environment to keep their calls private, without allowing killer whales to eavesdrop. It’s important to understand these whales and why they would take such risks to keep away from predators, and how they use their environment to their advantage

For more information, check out the original scientific paper:

Nielsen, M.L.K. et al. (2019) Acoustic crypsis in southern right whale mother–calf pairs: infrequent, low-output calls to avoid predation? Journal of Experimental Biology. 222:jeb190728.

A study conducted by researchers from the University of Iceland collected male  humpback whale songs from January to March 2011 in search of learning more about their migrating behavior. During this period, pods of humpbacks migrate from Arctic summer feeding grounds to winter breeding grounds in the Southern Atlantic, off of Florida and in the Caribbean. Males are known to produce vocalizations and songs to attract females around the mating season.

Through the winter breeding season, large numbers of males overwinter in their feeding areas and skip the annual migration. Scientists were astonished to find that that the males still sing their characteristic mating songs even when females aren’t  present. The researchers recorded songs using acoustic recorders and had a detection rate of 91% for the duration of forty-two days, with over ten, seventy-minute audio recordings. In these recordings, fifteen unique phrases were identified, and in these phrases it was discovered that the songs were remarkably similar to male’s songs heard in breeding areas. Whale songs from humpbacks are extremely mystifying and unique compared to other cetacean species. They change their songs every few years and never repeat the same tune. Rival males will mimic each other’s songs in hopes of attracting a female.

One researcher from the study believes the vocalizations were a response to food abundance claiming that the males are adapting to an ever-changing arctic environment by lengthening the period for feeding. It provides new data that shows whales may choose not to migrate during the winter breeding season because of changing water temperatures and food availability. Although there are many unanswered questions about why they vocalize and specifically why they “sing” when females aren’t present, new light can be presented on whale communication and social intraspecies interactions. Despite there not being any more recent studies or evidence of male humpbacks overwintering and singing in the arctic during winter, more precise conclusions can be drawn to the understanding behind the humpback’s unconventional actions. Which can cause further implications of males ceasing to migrate in the future and disrupt the annual migration pattern altogether.

For more information, check out the original scientific paper:

Walrus’ genus name “odobenus” translates to “tooth walking” because walruses use their tusks to pull themselves up onto a platform from being in the water. Walruses can grow up to 11 feet, and weigh up to 4,000 pounds. There are about 200,000 walruses in the Pacific ocean, about 18,000 in the Atlantic and 5,000  in the Laptev sea. The walrus is able to dominate the arctic ecosystems as they can withstand below freezing temperature due to their thick layers of blubber. Walruses were almost pushed to extinction between the 18th and 20th century, because they were being hunted by the people in the North for food, hides, ivory and bones. Once people began to notice that the walrus population was depleting rapidly, conservationist stepped in and laws were created to restrict walrus hunting. Now, only certain indigenous people are allowed to hunt walruses. The population of walruses were able to grow back, and are now only listed as vulnerable as they have a stable population growth. Just when walruses could catch a break, they are now experiencing a new danger that is threatening to wipe them completely: climate change.

Walruses dominate the cryosphere, which is the frozen water or the floating glacials, and this zone is heavily affected by the slightest climate changes. Walruses use this zone to give birth, feed and nursing, but their water is beginning to warm and melt some of those floating glaicals. The walruses have been able to adapt through climate changes and decided to find new platforms as a herd, as their usual platforms are now thin and melting. This caused them to deplete a lot of energy to search for a new platform, but they are able to move their habitat range in order to adapt to the change. Walruses have shown to be capable of great adaptability, and success, almost more than all marine organisms. An example of this is back in 1980’s, walrus had about 30 haul out spots scattered around Bering Sea, but overtime, their number of haul out spots has been reduced to 22, but their population was unaffected. It is still unknown if this is a natural adaptation or if this is hinting towards great danger in the future for them.

Walruses are observed to be ditching their ice platforms, as there is starting to be less food for them there, and moving to some coastal areas, without ice, to haul out. Walruses that choose to haul out on land, tend to be very very far from their food source, and have to travel back and forth, depleting more energy than usual, as they used to just drift on ice. This now threats female and young walruses as they have to travel very far each day, which poses various threats to their population. Polar bears are beginning to do the same, as they moved to coastal areas for food which overlaps with walruses food source range, and this poses great danger to walruses population. When a Polar bear spooks a herd of walruses, the entire herd would stampede towards the water to avoid predation, but in the process they are trampling over young walruses and usually killing them, which is causing the population to once again deplete.

There has been many legislation signed off to protect walrus population, such as the Polar Code, which basically restricts anthropogenic interactions with them, basically allowing walruses to live without any other disturbances in order to help their population grow back. Walruses have been able to adapt every year to climate change and find new answers to new issues that arise, but it is unknown how long they can push their population to survive while climate change is exponentially getting worse.

For more information, check out the original scientific paper:

Tsiouvalas, A. (2018), Walrus: The sensitive giant in the era of climate change: Climatic adaptation and challenges. Working and Living Environmental Protection, 15: 63-72.

For most dolphins, life out in the open ocean comprises of hunting with your peers, whether that means a small close-knit group, or a mob of strangers.  Dolphins, in general, retain smaller groups in shallow, protected areas, where predation stress is low, and form larger groups out in pelagic waters to increase predator vigilance and their effectiveness during hunts.  However, this is not the case for one population of Indo-Pacific bottlenose dolphins residing off the eastern coast of South Africa.  Algoa Bay is characterized as the largest and eastern-most bay of the south coast of South Africa.  It is shallow and has a maximum depth of 70 meters.  The largest average and maximum group size ever reported of bottlenose dolphins were found in Algoa Bay, with 60 and 600 respectively.  One thing that’s interesting is that this population stays stable over the course of seasons, but why?

Nearby at the Wild Coast, again we see the opposite of what we would expect; a smaller bottlenose dolphin population at an open pelagic site.  This area has a large amount of fish within it, including sardines.  Although we must take into account the amount of predators that would be concentrated in this area, we still would expect to see a lot there, however it is significantly less than Algoa Bay with only 33 on average and a 250 max group size, so what makes Algoa Bay so special?  Well researchers are still having a hard time figuring that out.

Group size for dolphins is largely influenced by food availability, predation pressure, or a combination of the two.  Taking this into account and the fact that the population generally stays stable over time, we have to conclude that area has enough food to sustain that large of a group.  Even with the added protection of the larger group, shark attacks still occur.  Perhaps the animals in this bay have found an abundant and easily obtainable source of food that researchers have yet to identify. Or perhaps there is another reason entirely.  All that we know for sure at this point, is that more research needs to be done to find the root of the cause

For more information, check out the original scientific paper:

Bouveroux, T. N., Caputo, M., Froneman, P. W., & Plön, S. (2018). Largest reported groups for the Indo-Pacific bottlenose dolphin (Tursiops aduncus) found in Algoa Bay, South Africa: Trends and potential drivers. Marine Mammal Science,34(3), 645-665. doi:10.1111/mms.12471

Off the coasts of Hawaii are two populations of melon-headed whales. Of these two populations, scientists have little previously known knowledge regarding the content of their diet and diving behavior until now. The nature of the Hawaiian and Kohala melon-headed whale populations has tapped into scientist’s curiosity to unveil more about this particular species. As such, it is recognized that further examinations of these species would be considered valuable pertaining to the further understandance of their foraging behavior.

Furthermore, stomach analysis was determined by eleven stranded whales from the Hawaiian islands, with ten recorded between 2009-2017, and one from 1985. Practices involved when interpreting prey content in the eleven stranded melon-headed whales were as follows: bones of the prey items were fixed in formalin once removed, followed by a freezing procedure for future use. They later were thawed and rinsed by sieves, preserving the bones in 70% ethanol. Remaining samples were stored in alcohol at the Marine Mammal Laboratory in Seattle Washington. To determine prey size and mass, regression equations were used. In regards to the dive behavior analysis, data was collected by depth transmitting satellite tags deployed between the years of 2011 and 2014. Photographic matches to known individuals of the two populations were used to affirm population identity. Likewise, tags were deployed during three recorded encounters with the species.

In this study by West et al, through the Marine Mammal Science journal, Peponocephala electra’s diet was studied. In this case study, the prey of the Hawaiian melon-headed whales consisted of fifty one identified species that collectively represented groups of fish and cephalopods. Examples of such fish and cephalopods include Myctophid lanternfish and Enoploteuthid squid. Although cephalopod concentrations in diet outweighed fish concentrations in diet, the fish were what was found to be qualitatively dominant. Thus, evidence suggests that these whales forage for fish rather than cephalopods (squid, octopus, nautilus) as a preferred prey item.

Contrastingly, the diving behavior data between the three tagged whales was however sufficient and similar. While two of the whales represented are from the Kohal resident population (different from the Hawaiian population), the similarity between diving behavior of the two populations suggests that the use of the water column in the slope and offshore habitats resemble each other respectively. However, while the Kohal resident population inhabit shallower depths of waters, the Hawaiian Island individuals do not. This data is supported by tag locations of these mammals, as melon-headed residents of the Kohal population are found closer inland than that of Hawaiian melon-headed residents.

In conclusion, due to the similarities between the two distinct populations concerning dive behavior with the exception that the Kohal population dive at depths shallower than the Hawaiian population, it is imperative that stomach content of the Kohala resident population is assessed and analyzed to compare to that of the Hawaiian population. Thus, further knowledge regarding the diet of this specific population will provide a means of distinct or equivalent data from that of the Kohal population. In like manner, while it was found that melon-headed whales prefer foraging activity at night as opposed to day, it is a clear indicator that the surface layer and middle layer of the open ocean are critical foraging grounds.

For more information, check out the original scientific paper:

West, K. L., Walker, W. A., Baird, R. W., Webster, D. L., & Schorr, G. S. (2018). Stomach contents and diel diving behavior of melon-headed whales (Peponocephala electra) in Hawaiian waters. Marine Mammal Science, 34(4), 1082-1096. doi:10.1111/mms.12507

What would you do if you were able to eavesdrop on the elaborate conversations throughout the ocean? What stories would you be able to piece together by just listening? Ida Carlen et al. set out to cue into the dialogue of the ocean with hopes of hearing the story of the Baltic Sea harbor porpoises.

Harbor porpoises, Phocoena phocoena, are located throughout the world but the individuals inhabiting the Baltic Sea are of particular interest. These porpoises are the only cetacean found in the region and are unfortunately considered critically endangered. These mammals are highly susceptible to fishing bycatch, noise pollution and other human induced activities. These small dolphin-like creatures continuously produce sound via echolocation, when communicating or hunting. The ocean commotion this species causes can provide crucial insight to their population status. Past studies reveal that two distinct populations of harbor porpoises have been found to inhabit the Baltic Sea. The Belt Sea population is currently still monitored and is managed under a previously established management border, which protects their breeding grounds and winter migration. The second population, the Baltic Proper population, is more elusive and their current status is unknown and believed to be critical. Due to this ambiguity on the Baltic Proper porpoises, eavesdropping on their habitat is essential if scientists have any hopes in recovering and monitoring their population.

The researchers deployed 304 C-PODS all throughout the Baltic Sea, which are passive acoustic devices that are capable of listening and recording the porpoise clicks from their echolocation. Over the course of two years, the team collected enough data to suggest that both the Belt Sea and Baltic Proper populations still inhabit the sea, but with no overlap in habitat location. During the breeding months, the Belt Sea population can be heard clicking away in the Southwest region while the Baltic Proper porpoises established breeding grounds along the offshore Baltic Proper region. The Baltic Proper porpoise reproductive habitat is not managed or within a protected area and therefore is at high risk of bycatch, increased ocean noise via shipping traffic and other ocean pollutants.

The researchers suggests that with their newly collected data, new protected areas can be implemented around the Baltic Proper breeding grounds. Fisheries can also be evaluated to replace the harmful gillnets with alternative gears and reduce overall bycatch. The research can also be taken into consideration when looking at the production of underwater noise from heavy ship trafficked areas. Acoustic deterrents, monitors similar to C-PODS that produced a ping irritating to the porpoises, can possibly prevent the porpoises from entering predominant shipping routes in the Baltic Sea.

Simply putting an ear to the waters of the Baltic Sea, allowed Ida Carlen et al. to reestablish a population of harbor porpoises, that would have potentially been pushed to extinction from human activity. With the Baltic Proper porpoise’s story piecing together, it’s easy to understand the importance of listening to our environment. Next time you’re near the ocean, listen and think, what’s the commotion of the ocean trying to say?

For more information, check out the original scientific paper:

Carlén, I., Thomas, L., Carlström, J., Amundin, M., Teilmann, J., Tregenza, N., . . . Acevedo-Gutiérrez, A. (2018). Basin-scale distribution of harbour porpoises in the Baltic Sea provides basis for effective conservation actions. Biological Conservation,226, 42-53. doi:10.1016/j.biocon.2018.06.031

Imagine you’re swimming in the ocean. The water is cool and calm, the air is warm and the sun is shining. Everything seems blissful. That is, until a massive white shark lunges from beneath the waves to devour you. Sounds pretty stressful, right? Well, fortunately for you that’ll probably never happen. Why? Because one you’re not a seal, and two, you’re not living on Seal Island arguably the most stressful environment for Cape fur seals.

Neil Hammerschlag, a professor at the University of Miami, has conducted a multi-year study off the Western coast of South Africa. He tested the predation-stress hypothesis, using the various colonies of Cape fur seals and their interactions with the surrounding white sharks. The predation-stress hypothesis, is as interesting as it’s understudied. The researchers explained that, “it predicts that exposure to risk causes increased secretions of glucocorticoids”. This study is one of few, to observe stress responses of prey populations in low and high risk areas of their natural habitat. The importance of this study is needed in the modern world as we lose predator populations and we don’t fully understand how they interact and impact their prey.

From this study, the researchers were hoping to learn 4 things about predation/prey stress. They were to:

1. See whether the different seal colonies displayed signs of spatial/seasonal variations of fecal-glucocorticoid metabolites (fGCM) in response to white shark attacks
2. Test if fGCM was found in higher concentrations where shark abundance and attacks were more frequent
3. Determine if features of a seal’s surroundings influenced the type, frequency, and magnitude of shark predation risk
4. See if there was a difference in physiological stress between adults and juveniles by looking at fGCM in their scat

To accomplish a study of this grandeur, the researchers had to first understand the Cape fur seals of the areas. Researchers determined that white sharks actively target fur seals of certain colonies, and only during the winter. During these months, predation risk is high, and different colonies experience more risk than others. The seals found in False Bay, most notably Seal Island, experience the highest risk of all. On average, they experience ~1.97 attacks per hour which is estimated to be about 18 times greater than seals inhabiting a separate colony on Geyser Rock-which only experiences ~0.1 attacks per hour on average. Differing landscape features may be the cause of this as False Bay is exposed without any kelp beds or coral reefs, which causes unpredictable predation.

The study followed tagged white sharks and tracked their abundance specifically to False Bay, Mossel Bay, and Geyser Rock. At each, seal scat was examined to determine if levels of fGCM correlated with white shark abundance and attacks.

The results of the study found that elevated levels of fGCM were found in areas exposed to frequent and unpredictable attacks. It was also found the fGCM rates did not correlate with adults/juveniles or shark abundance.

For more information, check out the original scientific paper:

Hammerschlag, N., Meÿer, M., Seakamela, S. M., Kirkman, S., Fallows, C., & Creel, S. (2017). Physiological stress responses to natural variation in predation risk: evidence from white sharks and seals. Ecology, 98(12), 3199-3210.

The invention of drones (unmanned, self propelled aircraft) has opened the door for innovation for a wide variety of applications in diverse career fields, but are they doing more harm than good? In wildlife management and research, drones are being used more often. The lower cost, maneuverability, and relatively low disturbance of the drones as compared to previously used sampling methods makes them highly desirable for research purposes.

Of course there is always a drawback. Drones produce noise, air disturbance, and to some species, may resemble predators, so understanding how drones may affect your target species is vital when planning to use them in research. If animals are easily disturbed by drone sampling, this can lead to unnecessary stress, and even biased data. Due to the novelty of drone sampling in most fields however, there is little viable data on how it affects most species. Which brings us to the blue whale.

So what do the whales think of this? Luckily, from the research performed by Carlos A. Domínguez‐Sánchez and his team, they don’t seem to mind. Blue whales are an elusive, long ranging species that little is known about. One way scientists can gain a lot of information from a single whale is blow sampling. This involves getting a sample of exhaled air and water from a surfacing whale which provides important health and demographic information such as hormonal levels and DNA. Drones provide a minimally invasive option for collecting this data. By flying behind a whale when it exhales, the drone can collect a sample and return it to researchers, who can operate the drone from a safe distance.

Domínguez‐Sánchez and his team observed whale behavior when approached by a drone performing a blow sample and compared it previous behavior observations and found there wasn’t any apparent difference in whale behavior. Previous observations not related to this study observed whales diving prematurely when drones approached from head on, which can affect their dive recovery and feeding behavior. The most important aspect of drone sampling they concluded, was to have a professional control the drone, and to follow the sampling protocol, which details how to approach the whale without spooking it. Of course, more studies will have to be performed for other species, but for now, we have the go ahead to use drones as a sampling tool, and hopefully we will gain a deeper understanding of these mysterious giants.

For more information, check out the original scientific paper:

Domínguez‐Sánchez, C. A., Acevedo‐Whitehouse, K. A. and Gendron, D. (2018), Effect of drone‐based blow sampling on blue whale (Balaenoptera musculus) behavior. Mar Mam Sci, 34: 841-850. doi:10.1111/mms.12482

The ability to recognize oneself in a mirror is an ability we all take for granted. Most of us have been amused by a dog barking at itself in the mirror or a cat jumping in fright as it passes its own reflection. Mirror self-recognition (MSR) is a behavioral trait only shared by a handful of species, which include humans, dolphins, elephants, the great apes, and magpies. MSR is indicated by self-directed behavior when the animal in question is confronted with a mirror. (For example, the animal exhibits repetitive behaviors or body parts otherwise unobservable.) In humans, the emergence of MSR is generally between 1 ½ and 2 years of age, and in chimpanzees, it is roughly between 2 ½ and 3 ½ years of age. At the beginning of this year, two researchers at the National Aquarium in Baltimore, MD sought to perform a study that identified the onset age of MSR in bottlenose dolphins. They performed mirror tests on two young dolphins named Bayley and Foster. The tests were simple, performed for one hour twice a week and consisted of putting a mirror in the dolphin’s pool and taking video footage for analysis. They found that bottlenose dolphins develop MSR capabilities at about 7 months of age. This age is significantly earlier than all the other species reported to exhibit MSR, including humans. One might be tempted to say that this discovery means that dolphins are more intelligent than humans. However, this is not necessarily the case. Dolphins do not show signs of some of the higher consciousness qualities of humans, such as reading and analytical deduction, but they do seem to have faster social development in the early years of life.  This discovery is a valuable insight into the early cognitive development of dolphins and their awareness of self. It is also a valuable contribution to the general knowledge of mankind regarding the phenomenon of consciousness, and how and why it develops in some species, including our own.

For more information, check out the original scientific paper:

Morrison R, Reiss D (2018) Precocious development of self-awareness in dolphins. PLoS ONE 13(1): e0189813. https://doi.org/10.1371/journal.pone.0189813

For decades sperm whales have been documented stranding all over the world. Many theories have emerged such as following food source and wandering off course, or changes in tide. But their true underlying causes and mechanisms still remain unclear. In a study published in the International Journal of Astrobiology, scientists conducted a study on a series of a total of 29 male bachelor sperm whales (Physeter macrocephalus) that occurred in the North Sea in early 2016. The astrobiologists (Vanselow, K., Jacobsen, S., Hall, C., & Garthe, S.) (2018)  believe that the mass strandings are actually due to geomagnetic storms on the surface of our sun.

Geomagnetic storms are temporary disturbances in Earth’s magnetosphere that is caused by large disruptions on the surface of the sun. This can range from solar flares to coronal holes in the sun and solar mass ejections. Large geomagnetic storms even have the possibility of causing major blackouts through the disruption of power grids. These geomagnetic storms typically occur 20 to 30 days post disruption on the sun’s surface.

How is it possible that a fiery storm millions and millions of miles away cause this you may ask? It is believed that sperm whales magnetic sense plays an important role in orientation, especially during migration. And as many of these sperm whales are younger and lack experience migrating to higher latitudes (where magnetic disruptions are stronger), it is very possible that they will become disoriented on the way during a geomagnetic storm.

Through close observations of storms that occurred in early to mid 2016, the scientists found that in higher latitudes, the magnetic field lines (in particular the North Sea) have a greater the vertical component. Cochran et al. (2004) reported that the vertical component is incredibly important for birds in order to calibrate their magnetic orientation with the setting sun once a day. Once again it is believed that this behavior applies to whales and if so it would explain the mass strandings of juvenile males who have never ventured into the North Sea.

It is important to note that 22 of the 29 whales that were stranded had autopsies performed on them and there were no visible causes of death. The stomach’s contained mostly marine biological waste and there was no indication that any of these whales were sick.

All in all, it is important to try to understand all theories and supported ideas on how we are losing not only sperm whales but other species of marine mammals as well, whether it is due to stranding or other. Solar storms do seem to have a correlation with whale stranding in northern latitudes, specifically the North Sea. However more evidence is needed to confirm this theory.

For more information, check out the original scientific paper:

Vanselow, K., Jacobsen, S., Hall, C., & Garthe, S. (2018). Solar storms may trigger sperm whale strandings: Explanation approaches for multiple strandings in the North Sea in 2016. International Journal of Astrobiology, 17(4), 336-344. doi:10.1017/S147355041700026X

Leopard Seals are considered an apex predator which means they are extremely important to the environment. An apex predator is a predator at the top of the food chain that has no other predators. They “feed on fish, other seals penguins and krill”. Their main diet consists of krill. This species have not been studied too much because they are hard to track because of the cold environment and the rough waters they thrive in. Just like every other type of seals, the leopard seals perform the action of a haul out. A haul out is when seals get out of the water to spend time on land or ice in this case.

The time that Leopard seals spend out of water has been closely observed and studied by Lain J. Staniland. He ran tests and studied the movements of leopard seals year round and what affects this type of activity. Leopard Seal “movements between and behaviour within areas important to breeding populations of birds and other seals shows that they are vital in the management of the southern oceans resources” (Staniland).  If leopard seals were to go extinct, it would cause a huge issue in the southern ocean ecosystem. The Seals that were tracked and examined when they were migrating to South Georgia and Bird Island showed that their haul out period was “between 22 and 31% of their time.’ ‘The maximum time spent in water was between 13 and 25 days’ (Staniland) before they hauled out of the water. There are many factors that play a role in the haul out time for leopard seals. During the summer time the haul out period was longer and happened more often than the winter because of the temperature difference between the air and the water.

Leopard Seals also migrate from Antarctic waters to sub Antarctic Islands. They do this for food mainly and also because of the temperature of the waters. They were found to migrate to Bird Island and South Georgia which is an island that has shallow shelf waters in which the leopard seals were perceived to like because they are shallow water hunters. The haul out behavior when the seals are spotted around this area is that, they will haul out mainly on open ice because they prefer colder environments and it will be more frequent than when spotted in warmer areas.

Leopard Seals are an interesting species and there is much more to learn about them. Hopefully in years to come we will be more knowledgeable on the species and get a better idea about the way they act in different environments and how they can adapt to stressful/different areas.

For more information, check out the original scientific paper:

Staniland IJ, Ratcliffe N, Trathan PN, Forcada J (2018) Long term movements and activity patterns of an Antarctic marine apex predator: The leopard seal. PLoS ONE 13(6): e0197767. https://doi.org/10.1371/journal.pone.0197767

Dolphins are smart, like seriously smart. The trouble is that they don’t speak english and, so it can be really hard to understand just what a dolphin is really feeling. In a study published in March 2018 by Isabella Klegg and Fabienne Delfour from the University of Paris, scientists devised an experiment to help understand how bottlenose dolphins think and how each has a unique disposition.

The scientists involved in the study focused on a particular set of actions called anticipatory behaviors. These behaviors are performed by dolphins when they are predicting an upcoming event. The study focused on two actions, spy-hopping and surface-looking, both actions involve the dolphin lifting their head above water and focusing their eyes on a trainer or object. From a human perspective these actions may seem to convey excitement, but the study looked deeper to try and understand what the actions can tell us about the stress levels and moods of the dolphins performing them.

The experiment involved 8 dolphins living in aquarium environment. The scientists set up in view of the pool while the behavior of each dolphin was recorded. The dolphins were then asked to swim away, touch a float and return to one of five stations across the pool. The dolphins were shown that the trainer on one end of the pool had a herring (tasty!), while the trainer one the opposite end only gave a short applause, but the rewards from the three trainers in between were left ambiguous. Each dolphin repeated the test with the trainers calling them back to a different one of the five stations each time. The amount of time that it took the dolphins to return to each trainer was recorded.

Unsurprisingly the dolphins returned most quickly to the trainer they knew would give them a herring and most slowly to the trainer they knew would only give applause. The surprising results came from the three ambiguous stations in between. The faster a dolphin returned to the trainer the more optimistic the dolphin was thought to be about getting a fishy treat. Dolphins which returned more slowly were thought to be pessimistic about their chances of receiving a treat. The return times for each dolphin were compared to the number of anticipatory actions exhibited before the experiment and an interesting result emerged.

Dolphins which performed more anticipatory behaviors, also had a more pessimistic disposition, meaning they returned more slowly to the trainers when they weren’t sure if they would get a treat or not. The scientists who ran this experiment think that, this may be correlated to stress levels, because a dolphin which places too much importance on receiving a reward may be lacking stimulus in other areas. Although we are still miles from truly knowing what a dolphin is thinking, the experiment has helped shed light on how we can interpret their behaviors and provide them with a better lifestyle.

For more information, check out the original scientific paper:

Clegg, Isabella L. K., and Fabienne Delfour. “Cognitive Judgement Bias Is Associated with Frequency of Anticipatory Behavior in Bottlenose Dolphins.” Zoo Biology 37.2 (2018): 67-73.

If you have visited the coast, you may have had the opportunity to see seals basking on the beach. These types of animals spend a lot of their time on land, which may be surprising considering their special features that make them efficient swimmers. Their blubber and flippers certainly help them navigate the ocean, though they still come up on land to mate and give birth to their pups. During this time, seals may flop and bounce across the beach at a slow pace, indicating that all of their special features for swimming come with a trade-off: they greatly limit terrestrial locomotion.

Kelsey Tennett and her team from West Chester University in Pennsylvania researched the “flopping and bouncing” movement of seals to characterize their terrestrial movements. The primary species of focus was the northern elephant seal, the second largest seal in the world. To understand their movement, the research team video recorded wild male northern elephant seals at Año Nuevo State Park in California in January of 2015 and 2016. During this period, seals were on the sandy beaches to breed. A total of 70 males were recorded as they moved freely throughout the beach. They measured the distance they traveled so they could calculate the seals’ speeds. Additionally, the video footage was used to closely assess just how the seals flopped and bounced.

Unlike terrestrial mammals, the researchers found that the northern elephant seals rippled their bodies and moved in a wave-like pattern, which they dubbed “spinal undulations.” Starting at the hind flippers, the seals lifted back portions of their bodies and shifted their weight until the neck extended out and the whole body was shifted forward. In other words, if you were to lay down on the ground face-down and only did the worm to move forward, you would be undulating like a northern elephant seal on land.

Tennett and her team found that undulations increased with velocity, which varied between about 1 and 5.5 miles per hour. Foreflippers and the pelvic region were used as support, though foreflipper movement did not increase with increasing undulations. In other words, no matter how fast times their spines moved, their foreflippers did not try to keep up with a “running” motion across the sand. Lastly, researchers compared the effort needed travel across the beach, and found that the mechanical power for the northern elephant seal was greater with increasing size.

There is no doubt that terrestrial environments are still very beneficial to seals to mate and breed, though their bodies adapted for swimming certainly don’t aid their locomotion on land. We can imagine just how exhausting it would be to exclusively do the worm all the time, so the next time we see seals basking out in the sun on the beach, let’s be sure to let them get their well-deserved rest.

For more information, check out the original scientific paper:

Tennet, K.A., Costa, D.P., Nicastro, A.J., Fish, F.E. (2018). Terrestrial locomotion of the northern elephant seal (Mirounga angustirostris): limitation of large aquatically adapted seals on land? Journal of Experimental Biology. 18-0117.

Off the west coast of Australia near Broome, tourists are well used to seeing a mother humpback whale and her calf. However, recent sightings much further south have led scientists to question just how far the calving grounds extend along these beachy shores. Intrigued by the number of sightings, Lyn Irving, a PhD student at the University of Tasmania, set out to conduct surveys to better understand just how far south humpback whales give birth.

Little is known about the specific range of humpback calving grounds, but usually females give birth to their calves within 30 degrees of the equator. During the summer months, humpback whales can be found near Antarctica, feeding on krill and waiting to begin their migration north. They begin this journey in the fall where many whales swim up the western coast of Australia. These whales belong to a subpopulation know as Breeding Stock D, which is the largest population of humpback whales in the world. The females will give birth to their calves in these warm, shallow waters where they are safer from predation by killer whales.

In order to track where the whales are giving birth, Irving and her team flew aerial surveys over the North West Cape of Australia, the location of southern calf sightings. Irving was on the lookout for neonatal humpback whales, or whales that are less than 4 weeks old, traveling north. This direction of travel would indicate that the calf had been born further south than where first spotted. Flights were conducted during 2013 and 2015. Overall, 105 calves were identified during the two-year study, of which 85 percent in 2013 and 94 percent in 2015 were neonates. Based off of minimum predicted calf population sizes, 20 percent of all calves of the Breeding Stock D population were expected to be born as far south as the North West Cape. This newly discovered calving ground is an extension of 1,000 km to the southwest of the currently known calving ground.

This recently unknown area is situated in an area of high human activity which could cause some future problems for the mothers and calves. As calves are entirely dependent on their moms and highly vulnerable to predation, protecting calving grounds is an important step to protecting the future generations of humpback whales. How calving grounds are impacted by humans will greatly influence the future size and stability of whale populations as a whole. For these reasons, it is very important for scientists to have a better understanding of the full extent of the calving range in order to better form policies that can protect and assist in the recovery of this majestic species.

For more information, check out the original scientific paper:

Irvine, L., Thums, M., Hanson, C.E., McMahon, C.R., and Hindell, M.A. (2017). Evidence for a widely expanded humpback whale calving range along the western Australian coast. Marine Mammal Science 34(2) 294-310

The Florida manatee is the only manatee species in the US, and is one of the most endangered aquatic species. Today, there are roughly 6,000 manatees in Florida, and around 85% of all identified manatees have been reported to have scars from boat collisions. Boat strikes are one of the leading causes for manatee deaths in Florida. Even a boat travelling at 13-15 mph can be fatal. The Florida manatee is very important to the marine environment and to humans as well. They eat an immense amount of seagrass in the coastal waters keeping the seagrass short and healthy. This makes the manatees a keystone species, which is the name given to species that play a critical role in their ecosystems. Without the manatees, the seagrass would become overgrown, causing the habitat to collapse and making it difficult for boats to pass through.

Scientists from Florida State University and Florida Fish and Wildlife came together to conduct an experiment on how the behavior of manatees changes in relation to boats to learn about how the species can be preserved. In their journal Manatee Behavioral Response to Boats, manatee behavior during boat approaches was examined to get a better understanding as to why boat collisions occur. It was conducted by tagging 18 manatees in the northern portion of Charlotte Harbor National Estuary over the course of  2 years. The manatees were released with two different tags. One of them, called a digital acoustic tag (DTAG) recorded their sounds, different types of movements, temperature, and the acoustic environment. The second tag is a GPS tag which tracks the manatees’ movements, and boat traffic was mapped in the area. Data was collected in multiple locations in Charlotte Harbor. The first year, data was recorded in Lemon Bay, and in Placida Harbor and Gasparilla Sound the second year. Data was recorded in non winter months because this is when boat traffic is at its highest. The manatees were observed by boat for several hours 2-4 days after the manatee has been tagged. All tags on the manatees were removed within a few weeks of the manatees being tagged.

Over the course of this study, a total of 346 boat passes were recorded. 72.5% of these boat passes were more than 50m from manatee(s), 19.1% were in between 50m-10m, and 8.4% were within 10m of manatee(s). The distance between manatees and boats had a significant effect on the manatee’s behavior. The most common changes were swimming speed, water depth, and scanning the environment. The boat encounters that were less than 10m away are the most relevant to boat strikes. In these close encounters, 89% of manatees changed their behavior.  The closer the boat, the more likely the manatees would change their behavior. One important finding was that manatees respond quicker to boats that are travelling slowly compared to boats that are travelling faster. This suggests that boat speed restriction zones are an essential management tool for reducing manatee injury and death due to boat strikes.

For more information, check out the original scientific paper:

Rycyk, A. M., Deutsch, C. J., Barlas, M. E., Hardy, S. K., Frisch, K., Leone, E. H., & Nowacek, D. P. (2018). Manatee behavioral response to boats. Marine Mammal Science, 34(4), 924-962. doi:10.1111/mms.12491

The sea otter is known for its cute and cuddly appearance, and it’s touchy feelyness. Who can’t smile at a picture of them holding paws or rubbing their faces? Other than being adorable, otters rely on their paws and whiskers (referred to as vibrissae) for a much more important use.

Sea otters can consume a wide variety of prey including crabs, mollusks and even fish, however most show a favorite and specialize in the capture of a specific prey item. Because their hunting grounds are often deep, dark, and cloudy they rely on touch to find their foods. Specifically, they rely on their very sensitive paws and whiskers to distinguish their prey in the soft substrate. Their impressive dexterity also allows them to perform the classic surface behavior of cracking mollusks and crabs with the use of a rock.

In a study done by Strobel et al., they looked at how sea otters performed underwater, and how long it took them to make decisions. A 4-year-old sea otter was trained for 17 months, using positive reinforcement to use just paws or just whiskers in both air and water. In place of prey she was trained to recognize grooved acrylic plates, getting a shrimp every time she touched a 2mm grooved plate. They tested her ability to tell the 2mm grooved plate from various other grooved plates ranging from 2.1mm to 5mm. A correct determination (choosing the 2mm plate) got her the reward of a large shrimp.

The same human experiment was done on land, although they didn’t get a shrimp for a correct answer. Four humans were blindfolded and asked to wear sound canceling headphones, then directed to determine which plate had smaller grooves using only their hands, again the 2mm grooved plate being the standard.

The results showed that this particular sea otter (and likely others) are slightly more accurate with their paws than whiskers and perform slightly better in air than water. But that wasn’t the surprising part, the surprising part was how she went about deciding what plate to choose. She always explored the right plate first then either selected that plate, or immediately chose the left plate and she only used her right paw. She remembered what the standard plate felt like and if the right plate didn’t feel similar enough, she immediately chose the left plate. This may however have caused her accuracy to drop, as the other plate got closer to the standard she tended to pick the one she touched first, which was always the plate to the right.

This showed a surprising likeness to the human experiment, in which the humans primarily used their dominant hand. Although the accuracy was about the same as a sea otter, the humans took considerably longer to make a decision. The average time for the sea otter was .2 seconds, the average for a human was 6 seconds. If the situation ever arose where humans needed to forage on the ocean floor, we would not outcompete these furry critters.

For more information, check out the original scientific paper:

Strobel, S. M., Sills, J. M., Tinker, M. T., & Reichmuth, C. J. (2018). Active touch in sea otters: in-air and underwater texture discrimination thresholds and behavioral strategies for paws and vibrissae. The Journal of Experimental Biology. https://doi.org/10.1242/jeb.181347

Did you know that the country of Qatar in the Middle East has the largest dugong population outside of Australia? What if I told you that the largest dugong group ever reported was spotted between Qatar and Bahrain? Researchers (Christopher D. Marshall, Mehsin Al Ansi, Jennifer Dupont, Christopher Warren, Ismail Al Shaikh, and Joshua Cullen) at various universities including the University of Galveston and Qatar University have been studying the large number of dugongs that seem to use the Northwestern part of the country for feeding purposes. The dugong, also known as the sea-cow, is the only marine mammal that is a strict vegetarian. They are incredibly unique, but sadly vulnerable in our changing ocean. There’s not a lot known about aspects like their distribution, life history, and population biology in the Qatar region, which is undergoing large changes from things like coastal development, and oil/gas exploration. According to local populations, dugongs are in decline. These declines are likely because of aspects touched on above, but in addition, a high number of bycatch from fisheries in the region should be mentioned, too. Even though dugongs are protected nationally and internationally, bycatch is a tricky issue to fix because of how much the people of coastal regions like Qatar rely on seafood. So, why do these sea-cows like the Northwest part of the country so much? It’s probably to eat, of course! Although the region is hypersaline, meaning really salty, there are a few species of seagrass that grow healthily in the waters surrounding Qatar. In the large congregations of dugongs observed by the researchers, the most common activity was eating. The reason that these animals were spotted in the large groups they were in is not concluded to be definite by the researchers, but they believe it may have something to do with behavioral thermoregulation. Behavioral thermoregulation is the act of modifying your behavior to become warmer, like when you huddle in closer to a person/people if you are cold to gain heat. So, what can we make of all of this? The study by Marshall et al. is important because it shows that the northwest region of Qatar is an important habitat for dugong populations, which are decreasing in size with our changing oceans. Although coastal development and oil/gas exploration in this part of the country has not begun quite yet, it will pick up soon enough, meaning that there are important topics of discussion regarding the conservation of the animals that live there. The researchers of this study advocate for a Marine Protected Area (MPA) to be established for the safeguarding of the dugong populations that the local people have grown to appreciate for what they are: incredible sea-cows, unlike any other marine mammal species!

For more information, check out the original scientific paper:

Marshall, C. D., Ansi, M. A., Dupont, J., Warren, C., Shaikh, I. A., & Cullen, J. (2018). Large dugong (Dugong dugon) aggregations persist in coastal Qatar. Marine Mammal Science, 34(4), 1154-1163. doi:10.1111/mms.12497

Imagine swimming through coastal waters in search of food when all of a sudden you happen upon a school of your favorite dining cuisine. Next thing you know, you’re caught in a net and dragged onto a boat without any warning. According to Lotte Kindt-Larsen and her research team, this phenomenon, known as bycatch, is one of the most impactful factors threatening a small toothed whale called the Harbor Porpoise.

Today, development of various technologies have started to combat this issue of bycatch by fishing vessels. A type of acoustic alarm system called pingers are the most common device used to provide a warning signal to marine mammals. This warning signal is meant to deter them from approaching the nets used by fishing vessels. These devices are placed directly on the nets, and have been shown to reduce bycatch rates in some studies. Although these devices have been mandated in many areas, it isn’t clear the range at which they can be heard, or if they are having any detrimental effects on these animals.

Over the span of 5 years from 2010 to 2015, Kindt-Larsen and her research team conducted studies on two common types of pingers. They were able to compare an older model (AQUAmark100), to a newer, updated model (AQUAmark300). They found that the newer model could be heard for much further distances, which is crucial for these porpoises to be able to avoid nets.

So the new model can be heard from farther away seemingly helping the porpoises, but does it negatively impact them in any way? Well, it seems that in some cases it might, according to Kindt-Larsen. Their study, as well as others, showed that these pingers can actually cause porpoises to abandon the area completely, although this also is dependent upon the oceanic noise pollution. In addition to displacement, some porpoises may actually get used to the alarm and begin to ignore it. This was the case with the newer model of pinger, but interestingly, they did not see habituation with the older model.

What is the best choice then? It is clear that pingers in general have various costs and benefits, but at the current time, better technologies have yet to be invented. So for now, we may have to settle with an imperfect deterrent while we work to implement and develop better ways to prevent bycatch. This way we can lessen the detrimental effects of bycatch, while still allowing hard working people to make a living through fishing.

For more information, check out the original scientific paper:

Kindt-Larsen, L., Berg, C. W., Northridge, S. and Larsen, F. (2018). Harbor porpoise (Phocoena phocoena) reactions to pingers. Mar Mam Sci, 00(00): 1-22. DOI: 10.1111/mms.12552

As we all know, marine mammals evolved from land mammals, but now they are very different in both morphology and behaviour. Can you imagine that seals and sea lions are close relatives with bears? It’s true. Mammals today may differ greatly, but in actuality share similar ancestors. So how do you determine whether seals or sea lions are more like their ancestors? David P. Hocking et al.(2018) has done a series of investigations to examine the anatomy and behaviour, that discovered that seals can eat like their ancient ancestors due to clawed forelimbs.

In anatomy, David P. Hocking and his team compared the forelimb structure of seals, sea lions and fossil seals. They found that true seals have flexible digits and strong claws, which is similar to terrestrial carnivores, while an sea lion’s forelimb digits are integrated to form a stiff, wing-like flipper. This phenomenon suggests true seals tend to be more like their ancestor since all marine mammals evolved from terrestrial mammals. In addition, the bone of true seal’s knuckle is trochleated (functions like a pulley), which is similar to that of Enaliarctos, which are the ancestors of pinnipeds, and also that of terrestrial carnivores, while the sea lions’ are flattened.

In behaviour, David P. Hocking and his team observed 123 wild seal’s feeding events in Scotland and 20 seal’s captive feeding trials at the Alaska SeaLife Center. They found that wild northern true seals routinely use their primitive forelimbs to assist with processing large prey, which is called’ Hold and tear’ processing. As for sea lions, they preferred to use ‘shaking’ behaviour to process large prey, which is similar to other aquatic mammals like bottlenose dolphins. However, modern terrestrial and semi-aquatic carnivores also use their forelimbs to secure prey while it’s processed using the teeth. This suggests that true seals retain the feeding behaviour of ancestors during the transition from land to sea.

A more interesting fact is that true seals are often considered to be more aquatically adapted than sea lions because of the hind limb for aquatic locomotion and the ability to dive deeper. Therefore, I can confidently say that the seals are one kind of amazing animals that retain the anatomy and behaviour of their terrestrial ancestors and are well adapted to the aquatic environment at the same time. What’s even more fascinating is that these features of seals are adapted to the first stage of transition from feeding on land to feeding completely underwater, providing us the understanding of how species cross the boundary between terrestrial and aquatic existence in behaviour and anatomy.

For more information, check out the original scientific paper:

Hocking DP, Marx FG, Sattler R, Harris RN, Pollock TI, Sorrell KJ, Fitzgerald EMG, McCurry MR, Evans AR. (2018) Clawed forelimbs allow northern seals to eat like their ancient ancestors. R. Soc. Open Sci. 5: 172393. Available at http://dx.doi.org/10.1098/rsos.172393

The speed you drive your boat around manatees may actually be a case of life or death for these creatures.  Manatees are a vulnerable species with populations decreasing constantly.

One study by Athena Rycyk et al., done in the southwest region in Florida, found that boats affect important manatee behavior.  The behaviors affected are heading, rolling, fluking, and depth changes.  Eighteen manatees were captured, tagged with a GPS and DTAGs, released back into the waters, and were ready to be followed!

With the four behaviors being observed, a baseline for normal behaviors was defined.  The heading behavior is when a manatee sticks its head out of the water.  Fluking is a behavior that was rated as low, intermediate, or high depending on how many strokes the manatee displayed.  Depth change is how deep a manatee dove with a boat present compared to how deep they would normally dive.  Rolling is a behavior in which a manatee will roll sideways and do a complete circle.

Boat collisions are very common in this area and have been a leading factor in mortality within this population of manatees.

This study found that when looking at a whole, the speed of a boat doesn’t have a significant difference of behavioral changes in manatees.  However, slow driving boats did allow for manatees to have more time to respond to an approaching boat and the behavioral reactions did occur faster with the slow speeds.  When multiple boats were present, the speed did not really matter because all of the noises confused the manatees and caused more behavioral changes.

Not only is boat speed an issue but also how close you go to the manatee.  Close proximity (within 10m) causes the worst effects in behaviors exhibited by these manatees and causes more damage than the speed at which the boat was going.  This information is interesting to know because, the way they conducted the study was by following the manatees by boat.

When using your boat on the water, make sure you’re cautious of the speed you are going and if you spot a manatee in its home, do not get to close!  If you want to see the manatee, turn your boat off and let them approach you since you’re the guest in their home.

For more information, check out the original scientific paper:

Rycyk, A., Deutsch, C., Barlas, M., Hardy, S., Frisch, K., Leone, E., Nowacek, D. (2018). Manatee behavioral response to boats. Marine Mammal Science

At 29 weeks old, a human fetus can hear sounds coming from outside its mothers body. At this age, the part of the baby’s brain responsible for processing sound is only half way formed. Now imagine if this part of the brain was fully developed at only a few weeks old into pregnancy. What would the brain look like?

The answer to this question lies within the findings of a recent study on dolphin brain development. The study focused on forty-two different dolphin species and nine species of baleen whales, noting the factors that contributed to increased brain size in each species. The study found that a baby dolphin is born with a brain already half the size of its fully formed adult brain. For reference, our babies are born with only 20-30% of the adult human brain volume. While we have our fastest period of brain growth during the first three years of life, dolphins experience this rapid brain growth period while still in the womb. The study also found that dolphin fetal brain development is related to how long the mother’s gestational period is. So, you might wonder whether this means that if we also had 18 month long pregnancies like killer whale moms, maybe our newborn’s brains would double in size.

However, we have to take into account that dolphins live a very different lifestyle from the typical human. Dolphins use echolocation as a form of sight and communication. They use it to hunt for prey, talk to each other, and find mates. Developing echolocation requires a lot of brain power. Nonetheless, it’s been argued that echolocation doesn’t require a large brain as bats use echolocation but lack brain size. It’s difficult to compare the echolocation of a dolphin to a bat’s though, because a dolphin’s prey is almost the same density as the water surrounding it. To combat this, dolphins use fast pace high frequency clicking while hunting which requires rapid information processing. The development of echolocation is believed to attribute to a dolphin’s advanced auditory system resulting in a larger brain size and accelerated fetal brain development.

But don’t larger animals have larger brains? Although a dolphin mother’s body size was proven to be correlated to their baby’s brain size, the brain sizes of terrestrial mammals of similar body size were still significantly smaller. One major difference between dolphins and their terrestrial counterparts is diet. While the land mammals of similar body size such as elephants and cows typically consumed an all vegetarian diet, the dolphins are carnivorous feeding on high energy foods like fish. This energy is consumed by the mother which then enters the baby through the umbilical cord, facilitating brain growth

Studies like this one help supply knowledge so we can better understand how life works. This new information has opened many doors for future studies on mammal brains and can even be applied when examining our own.

For more information, check out the original scientific paper:

Ridgeway, S. H., Carlin, K. P., & Van Alstyne, K. R. (2018). Delphinid Brain Development from Neonate to Adulthood with Comparisons to other Cetaceans and Artiodactyls. Marine Mammal Science, 34(2), 420-439. DOI: 10.1111/mms.12464.

For more information, check out the original scientific paper:

Here’s a question for you—how well do you think that you would be able to live off of the land if the necessity ever arose? I mean, sure, you can manipulate that smart phone in your pocket with ease, but how about reading the land for signs of potential food and water, or finding safe places to set up a camp? Or setting up a camp?

My point is, the modern luxuries of life may have dampened those ancestral skills and instincts that kept the human species alive in the days of hunter-gathering. Native peoples, however, still rely on those skills for subsistence. This knowledge of the environment, that comes from years of observations and experiences with the land, passed down from one generation to the next, is invaluable to native peoples’ survival.

Researchers interested in Beluga health monitoring in waters north of Alaska and Western Canada were interested in tapping into this native know-how, or traditional ecological knowledge. This is no easy task, as it can be difficult to convince native peoples to share their knowledge. No surprise, as their concerns stem from fears of their knowledge being taken advantage of, or misconstrued in translation, as scientists attempt to quantify their livelihoods.

However, the researchers recognized the importance of integrating scientific knowledge with traditional ecological knowledge in order to co-monitor Beluga health in this region, an increasingly important task as the environment is beginning to see rampant changes with climate change.

Through a combination of public meetings, questionnaires, interviews, and focus group review, the researchers made efforts to record accurate information and fill any gaps in knowledge with the Western Canadian Inuit. The focus group of native peoples had to reach a 2/3 majority in order to determine if the described characteristic was enough to qualify as a recommended health monitoring measure—for example, sick whales were said to be slower and to surface more frequently to breathe, however it was said that sick whales could dive normally as well, so this did not become a recommended marker of Beluga health.

The researchers considered the suggested health indicators the Inuvialuit research participants conveyed, and made monitoring recommendations based on them. Whales were considered thin and likely starved when their backbone stuck out and they had thin blubber at the chest, with a lot of rolled skin. The backbone as an indicator of health would be monitored with the survey questions, body condition charts, and maximum girth measurements.

Native knowledge can have significant insights on the environment or a particular species. Documenting traditional ecological knowledge is up and coming in the scientific world, however it is important that researchers working with native peoples take the utmost measure to ensure respect and accuracy of the data that is being willingly shared with them—nothing would be worse than sharing your livelihood, how your people have existed for generations, only to have an outsider trample all over it or take advantage.

For more information, check out the original scientific paper:

Ostertag, S. K., Loseto, L. L., Snow, K., Lam, J., Hynes, K., & Gillman, D. V. (2018). “That’s how we know they’re healthy”: the inclusion of traditional ecological knowledge in beluga health monitoring in the Inuvialuit Settlement Region. ARCTIC SCIENCE, 4(3, SI), 292–320. https://doi.org/10.1139/as-2017-0050

While sea otters are widely known as top predators and keystone species, studying their diets proves difficult because they often exhibit more shy behaviors when humans are present. In fact, they often will stop feeding and hunting altogether when humans are observing. So, how to study these elusive yet voracious predators?

Sarah Strobel of University of California Santa Cruz’s Long Marine Laboratory enlisted the help of a four-year-old female sea otter by the name of Selka to help answer how sea otters are so successful at hunting small invertebrates such as urchins and mussels at dark depths in the ocean in which vision is limited. The researchers hypothesized that since sea otters dive to hunt in these areas of limited light, they likely have other heightened senses to help them find food.

To study exactly how efficient sea otters are at touching the world around them to find food, Strobel and the other researchers experimented with a single sea otter first by teaching her to recognize a board with two millimeters grooves in it. They did so by utilizing classic positive reinforcement training over the course of seventeen months. Each time Selka interacted with the grooved board in a way that was helpful to the researchers, she was rewarded with food. Since the sensory systems in question were the otter’s paws and whiskers, Selka was rewarded with her favorite treat any time she touched the board with those body parts.

After seventeen months of becoming familiarized with the two-millimeter grooved board both in air and water, the true test of Selka’s ability began. In each test, she was led to a contraption which allowed either her only her paw or face (equipped with blindfold so that she could not see) to touch the objects, depending on whether her paw or whiskers sensitivity were being tested. She was prompted to select the board that she had been familiarized with for seventeen months over a board that had both wider and narrower grooves. When she selected the correct board, just as in the training exercise, she was rewarded with food.

The results? Sea otters are pretty darn good at detecting their environment using touch. Compared to humans tested in the same experiment, Selka was 30-fold faster with her paws than human hands. She was slightly slower when using whiskers compared to paws, but still impressively quick. Considering she and other sea otters dive in dark environments for such small animals to eat, this decisiveness is certainly an important ability.

For more information, check out the original scientific paper:

Strobel, S.M., Sills, J.M., Tinker, M.T, Reichmuth, C.J. (2018). Active touch in sea otters: in-air and underwater texture discrimination thresholds and behavioral strategies for paws and vibrissae.  Journal of Experimental Biology: 221.

In the world of marine mammology, vocalization in marine mammals is not a new phenomenon for scientists. However, the manatee is an up and coming study subject on the matter. Specifically, scientists Rebecca Umeed, Fernanda Loffler Niemeyer Attademo and Bruna Bezzera are looking into the vocal behaviors of the Antillean manatee in their most recent study, “The influence of age and sex on the vocal repertoire of the Antillean manatee (Trichechus manatus manatus) and their responses to call playback” (2018).

Vocal acoustics, or the production of sound by an animal, is often found to be the main form of communication among individuals in environments that are less suitable for other senses, such as a marine environment. Hearing in manatees is suggested to be their main sense, as sight and smell can often fail them in the muddy waters they inhabit. Previous research on the hearing range of manatees is unclear, categorizing their auditory range anywhere from very broad to very narrow ranges. These results make it difficult to characterize why manatee vocalizations are observed. Other research looks to mother-calf pair vocal recognition as a tie to why manatees vocalize, along with individual recognition and mating opportunities as is found in other marine mammals.

The basis of the study set out to fill in the gaps of manatee sounds that other studies haven’t filled. Researchers wanted to characterize the different vocal repertoires observed in adult and juvenile manatees of both genders, and to see if there is a response to vocal recordings replayed to them underwater. By the end of the study, the researchers had characterized 6 distinct vocal patterns observed in adult males (4), adult females (7) and juveniles (3 males, 1 female). Of those vocalizations, squeaks, screeches and trills were observed in all groups while some specific calls were associated by gender: whines were associated with adult males, creaks with adult females and rubbing with juveniles. Young manatees were found to have longer calls than adults, and females had lower frequency calls than males.

Data was also collected on the manatee responses to vocal pattern playback collected from some of the same individuals in the study. When these different vocalizations were replayed to them (squeaks, screeches and trills), visible physical responses and increase in vocalization from every individual was recorded. Responses were recorded from all manatees when every vocalization was played, and the silent control elicited no response.

From the data collected in the study, it is suggested that manatees have a wide range of hearing capabilities, as well as multiple vocalization types through their life stages and between genders. Data also supports the recognition of vocal signals from playback of recordings due to physical and vocal response in the animals, and thus vocal communication between individuals other than mother-calf contact. Further research is suggested to characterize what exactly these vocalizations are being used for.

For more information, check out the original scientific paper:

Umeed, R., Attademo, F. L. N., Bezerra, B. (2018) “The influence of age and sex on the vocal repertoire of the Antillean manatee (Trichechus manatus manatus) and their responses to call playback”. Marine Mammal Science, 34(3): 577-594.

Wish you could talk to animals and truly understand what they’re feeling?  From movies such as the Dr. Dolittle series and role models such as Disney Princesses, talking to animals has been a talent many of us wish to possess.

A need for this talent has increased as publicity of animal care facilities has increased, in both positive and negative ways.  Many people question the safety of the animals within captivity due to past negative occurrences.  This is caused by assumptions made about how these animals feel based on what we see.  However, not enough research has been done to look at the animal’s emotional state which is why Isabella Clegg and Fabienne Delfour created the Marine Mammal Welfare Assessment, an assessment which measures three components of the animal: behavior, physiology and cognition to determine the health of a captive marine mammal.

These three components of welfare are used to understand the overall emotional response of the marine mammal through the use of the Triangulation principle.  This principle places the three components of welfare as points on a triangle with the center being the animal’s true emotional response.

While many facilities already use enrichment programs and toys to enhance the captive surroundings some researchers believe it may not be enough and only creates short-lived happiness for the animal.  With so little known about how these animals truly feel, the welfare assessment seems to be the best approach.

This assessment was evaluated on captive Bottlenose Dolphins, as the first marine mammal tested.  The study measured each component (physiology, behavior and cognition) separately.

During the physiology assessment researchers measured cortisol (stress) levels, respiration rate and dive depth of the dolphins.

The behavior assessment consisted of testing for social stress and instability, close bonds, cooperative behavior and prosocial tactile behavior (grooming and playing) between individual dolphins within a group.

The cognition assessment was the most difficult test to measure for therefore the only measurement the researchers have found and tested for was whether the dolphin favored the left or right hemisphere of their brain.  This was done by seeing which side of their body adults placed their young when they sense danger.

All these measurements were compiled and together determined the emotional response of the dolphins which was deemed mostly positive.   It was viewed in the behavior assessment that some dolphins didn’t get along with other ones, so changes were made to accommodate each dolphins’ need.

Using this welfare assessment could help animal care facilities truly understand what their animals are feeling and change their procedure to better fit the animal, like a teacher explains a concept in different ways to accommodate for multiple viewpoints.

Welfare research is new and expanding.  By evaluating how these animals feel while in the wild and in captivity researchers can gain a new insight to these creatures that could never be considered before.  Instead of humans saying what these animals feel, they can tell us.

For more information, check out the original scientific paper:

Clegg, I. and Delfour, F. (2018). Can We Assess Marine Mammal Welfare in Captivity and in the wild? Considering the Example of Bottlenose Dolphins. Aquatic Mammals, 44(2), pp.181-  200.

Manatees are marine mammals that may go unnoticed. Maybe you might know them better as the ‘sea cow’. The gentle giants, that can get to an impressive age of 60 years were once known as endangered, but are now listed as a threatened species. Under the protection of both the Endangered Species Act and the Marine Mammal Protection Act, the manatee’s numbers have steadily increased since the 1970s to somewhere over 6000 individuals. Now I know that they might not be as popular as your humpback whales or bottlenose dolphins, but they are still at risk of boat collisions, particularly off the southwest coast of Florida. In fact, it was found that 25% of manatee deaths resulted from reported boat collisions as well as 54% of adult manatee deaths where the cause of death was known.

Rycyk and colleges performed a study in the northern portion of the Charlotte Habour Estuary, an area with heavy boat traffic, to determine what manatees do in response to boats. A total of 18 manatees were studied with two already having fresh boat wounds. To measure their responses they fitted the manatees with some nifty tracking gear, DTAGs that record sounds, as well as recording aerial videos from above. This allowed them to track where the manatees were in the water, the sounds that they and the boats produced as well as seeing what their behaviours were.

Boats travelling off the southwest coast of Florida can hits speeds of more than 32 km/h. I know this may seem slow, but think of it this way, manatees usually travel at a speed of 8 km/h, which is four times slower than these zooming boats! Faster moving boats have been shown to pose a bigger threat to manatees than slower boats since they have less time to react.

During the study most boats didn’t approach the manatees closer than 50 m but, there were still boats passing them being within 10 m. They found that when boats passed within 10 m of the manatee that 89% of them had a behavioural change within 22.7 seconds. These behavioural changes included diving to deeper water, swimming faster, lifting their tails and heads out of the water and rolling. If a big, loud, scary boat was coming towards you, I’m pretty sure you would try move out of the way too.

So what is currently being done to ensure the safety of these slow, gentle creatures? Several management tools have been put in place in an effort to reduce mortality. Things like speed-restriction zones can reduce the severity of injury to these animals if they happen to be hit. Manatee sanctuaries can ensure they have safe areas to roam free. Also local plans and reviews of boat facilities can help to ensure boat traffic isn’t in highly populated areas. So these tools are useful strategies to reduce collisions of manatees, but how effective are they really? Will better rules and regulations need to be placed in the future in order to better protect this species?

For more information, check out the original scientific paper:

Rycyk, A.M., Deutsch, C.J., Barlas, M.E., Hardy, S.K., Frisch, K., Leone, E.N & Nowacek, D.P. (2018). Manatee behavioural responses to boats. Marine Mammal Science, 34(4): 924-962. doi: 10.1111/mms.12491

I’m sure we’ve all been asked this, “would you rather lose your sense of sight or hearing?” Many of us might consider these to be the most important of the five basic senses that we have as humans. For the environment in which we inhabit those senses could very likely be our most important. But consider you live in a world where both vision and audibility are strongly inhibited, what then? Well for amphibious mammals, such as the sea otter, this is the type of world in which they live. When foraging on the sea floor for food, visualization of their surroundings is increasingly difficult compared to in air, and nearly impossible after the sun sets. While also lacking the adaptations for auditory communication and navigation like other marine dwelling mammals (such as dolphins), how is it that the sea otter can locate food so successfully? The answer lies in their paws and face, where the sea otters are very well-developed for tactility (sense of touch). But just how good is the sea otter’s tactile sensibility? How does it compare to humans, who also have an extremely well-developed sense of touch?

A recent paper, Active touch in sea otters: in-air and underwater texture discrimination thresholds and behavioral strategies for paws and vibrissae by Sarah McKay Strobel et al., explains a study that explored the discriminatory abilities of sea otter’s touch. This study used a single mature female otter that was trained to perform the tasks needed to undergo this investigation.

In this experiment, the otter needed to display its ability to discriminate between textures in both under-water and open-air environments, using either her paws or vibrissae (whiskers). To do this, the scientists created an apparatus that presented the otter with two different plates side by side. Each of these plates had grooves of different widths machined into them, and one of the two options was deemed the “correct” plate. The otter had been pre-exposed to the “correct” plate’s groove width during training. During experimentation the otter was always given the option between a correctly grooved plate and an incorrect one to choose between. While having only the sense of touch to rely on, the otter needed to correctly distinguish between the two and make a correct decision. Interestingly, in terms of numbers of correct answers, the sea otter had achieved sensibility of a similar level as human subjects who were put through comparative testing. However, the sea otter had response speeds that surpasses that of humans by a long shot, with her paws she was 30-fold faster than humans and 15-fold faster in her whiskers.

The results of this investigation lead us to begin understanding the adaptations that allow for sea otters to be the highly efficient top predators that they are. Such rapid and accurate tactility likely allows for incredibly effective foraging, that may otherwise be challenging if relying on other senses.

For more information, check out the original scientific paper:

Strobel, S.M., Sills, J.M., Tinker, M.T, Reichmuth, C.J. (2018). Active touch in sea otters: in-air and underwater texture discrimination thresholds and behavioral strategies for paws and vibrissae.  Journal of Experimental Biology: 221.

Picture a scientist. What type of person do you see? What do they look like? Chances are, if you are in the majority of the population, you pictured an elderly man such as Albert Einstein or Steven Hawkings.

The idea of the stereotypical scientist is so ingrained in our culture that it’s difficult to combat. However, for the past few decades, we have been trying to do just that. More and more women have been entering into scientific fields such as the marine sciences, to help increase gender diversity, but the representation is far from equal. The further you travel up the ranks, the less you can find women represented. This is called the ‘leaky pipeline.’

What causes the ‘leaky pipeline?’ According to Sascha Hooker in her article “Equity and career-life balance in marine mammal science?”, the cause can be a mix of different things: through both internal and external decisions. Statistically, women are more likely to focus on “work/life balance” than men, prioritizing family over career building. Scientific jobs, especially marine mammal focused studies, are incredibly time and labor intensive. Many marine mammal research jobs require frequent traveling for long periods of time. Dolphins and whales don’t care whether or not you have children at home; they travel out to sea whether it’s convenient for you or not.

Another possible cause for the lack of ladies in the upper scientific community could be because they simply haven’t had the time to climb the ranks. Until fairly recently, around the late 20^th century, women were not allowed to work aboard research vessels or work in the Antarctic with the men. Even now, the deep-set bias towards men in science remains. All male faculties are more likely to hire men than women, while at the same time not accepting the evidence for gender-bias in science. As a result, it becomes increasingly difficult for women to gain ranks the higher they climb.

So how do we plug the leaky pipe? Hooker suggests a few possible strategies to help increase women representation in the sciences including: increased focus on mentorship, intentional gender equalization in hiring, and forming discrimination and harassment positions in the Society for Marine Mammalogy. In addition, she suggests encouraging women to pursue career advancement. While these solutions are a step in the right direction, much more work is required before the sciences can achieve true gender equity. Until then, the scientific community lacks a valuable perspective in many areas of research that can be provided through a woman’s touch.

For more information, check out the original scientific paper:

Hooker, S. K., Simmons, S. E., Stimpert, A. K. and McDonald, B. I. (2017), Equity and career-life balance in marine mammal science?. Mar Mam Sci, 33: 955–965. doi:10.1111/mms.12407

When looking at the environment we can use certain species as an indicator of possible health risks and issues that may end up being prevalent to humans. One species that is an indicator of environmental health are bottlenose dolphins (Tursiops truncatus). Scientists, Leslie Hart, Kerry Wischusen and Randall Wells are doing just that but in an unexpected manner.

Scientists look at something known as reference intervals (RIs) to set a base of what is considered healthy and normal for a specific species. But, how do you get detailed information quickly when working with such a large animal? The answer: an app. This method has been looked at as a new way to determine if an animal is combatting health issues due to environmental stressors in real time!

So how do scientists do health assessments on these dolphins which can be anywhere from 10-14 feet and upwards of 1,000 pounds? Dolphins are moved to shallow water where scientists are then able to draw blood as well as do a quick examination on the animal. Some individuals were lifted out of the water to be weighed, and measured, to collect samples. All this data was put into an app, “Cetacean Health”, which was developed by using an app inventing software created by MIT. The app was then able, after some calculations  to determine if the dolphins were under or overweight as well as other details about their health. Additionally, the app creates graphs that provide a visual component to any data collected. This allows scientist to determine where the dolphin falls on the health scale.

After the initial tests were done, the app was brought into the field to test how practical the use of an app actually was. And it worked! The overall consensus was that the app was a fast and easy way to get data processed quickly, which is important when looking at species that are susceptible to stress. This is something that scientists and veterinarians can bring onto the field to quickly asses the environmental impacts on the species. This could also lead to more apps that engage people in citizen science where everyday people can record what they see on any excursion they may go on and report data. Guess there is an app for everything.

For more information, check out the original scientific paper:

Hart, Leslie B., Kerry Wischusen, and Randall S. Wells. “Rapid Assessment of Bottlenose Dolphin (Tursiops truncatus) Body Condition: There’s an App for That.” Aquatic Mammals 43, no. 6 (2017): 635-44.

In mammals parenting and watching over young is primarily done by the mother, but in some species other individuals lend a hand (Augusto et al. 2017). Alloparenting, or alloparental care, is the watching of young by another member of its species that is not the biological parent of that individual, and is similar to the human behavior of babysitting. This behavior is beneficial to the young as it provides increased protection, grooming, huddling, and food resources (Gubernick et al. 2000).

In the paper ‘Characterizing alloparental care in the pilot whale (Globicephala melas) population that summers off Cape Breton Nova Scotia’ lead scientists Joana Augusto, Timothy Frasier, and Hal Whitehead studied the relatively unknown parenting behavior of this species. Observations were made from a whale watching vessel that crossed through Pleasant Bay Harbor, this trek was repeated five times each day from 2009 to 2011.

Specifically Augusto and her team were attempting to determine the amount of time a calf and adult spent together to determine what they called “closest companions”. Alloparenting was characterized as the observation of two or more close companion encounters between a calf and an adult, who was not the mother. Identification of individuals was determined by photographing the whales fins or characteristic features.

By the end of the study the team had collected 661 encounters of pilot whales, 85.9% of which included calves. They were able to identify 356 calves, but only 92 were observed to have over two closest companionship encounters with individuals other than their mother. The findings also showed that over 50% of the calves were observed with more than one companion and were escorted by the pod as a whole.

From the data collected on the whale watches it was determined that alloparenting behavior was performed by whales unrelated to the calf, and each event was short lived. This was an unexpected outcome, because it was assumed that alloparenting would occur in closely related whale groups, as they are longer lasting and more tight knit (Augusto et al. 2017). The researchers also found that most of the babysitting was done by the males, stated to be a positive social experience for calves similar to bottlenose dolphin or sperm whale socializing (Whitehead et al. 1996). Finally, it was also determined that alloparental care can be altruistic to the adults monitoring the young, but benefit the species as a whole (Augusto et al. 2017). Because this is a behavior that does not directly benefit the whale performing it, Augusto stated that “ there is no evolutionary mechanism associated with the behavior, and alloparental care is a byproduct of this species’ social structure”.

Alloparenting was seen to be a common occurrence in the Cape Breton pilot whale population, a behavior likely to have a positive affect this species. Having numerous individuals watch over the young is important for pilot whales, as escorting and constant calf care reduces the risk of predation and increases the calves overall probability of survival.

For more information, check out the original scientific paper:

Augusto, J. F., Frasier, T. R. and Whitehead, H. (2017), Characterizing alloparental care in the pilot whale (Globicephala melas) population that summers off Cape Breton, Nova Scotia, Canada. Mar Mam Sci , 33: 440–456. doi:10.1111/mms.12377

If you have ever experienced a neighbor doing home improvements on their house, then you know the headache early morning construction can cause. Harbor porpoises face a similar problem with offshore wind farms being built. The foundations for these turbines require high-powered hammers which cause sonic sound waves when pounded into the sea floor. Unlike your neighbor who may knock on your door and warn you of the noise, unsuspecting porpoises in the wind-farm areas temporarily lose their hearing, making them vulnerable to predation. The noise also drives porpoises far from home, sometimes at distances of ten to fifteen miles. Germany and the United States recently made regulations specifying construction can emit no more than 160 decibels of sound during projects requiring these hammers. To put that into perspective, Boeing jets taking off emit a sound of 165 decibels and the human eardrum breaks at 160 decibels.

Scientist Michael Daphne and his team in Germany worked with DanTysk Offshore Wind Farm to help reduce noise disturbance for harbor porpoises while they built 80 turbines. One of the tools used was a Seal Scarer which was originally designed to make noise that deters seals but proved to be useful for porpoises too. They also used a pinger with a similar sound frequency to porpoise calls so the porpoises could hear the warning and turn around before the construction noise was unbearable. They even used bubble curtains. Traveling through an air bubble curtain made from compressed air in a tube, sound waves are reduced because air is less dense than water. Bubble curtains covering a .099-mile radius around the construction ensured porpoises were protected from every direction. Meanwhile, scientists monitored the local porpoises to see how they responded. They found the bubble curtains muffled the noise and contributed to less habitat loss because it allowed the porpoises to stay closer to the noise. The pingers and Seal Scarers helped porpoises avoid hearing loss but the Seal Scarers were just as bad as the construction at keeping the porpoises far from home.

Overall the project was successful but using Seal Scarers is being reevaluated. If you go to enough rock concerts, it’s inevitable that after a while you would have some permanent hearing loss. Similarly, when porpoises are exposed to multiple noisy projects, the scientist suspect it could have a larger effect on porpoise populations. The methods described by these scientists could help other developers to construct their alternative energy without disturbing marine life. Besides, it’s what a good neighbor should do.

For more information, check out the original scientific paper:

Daphne, M, et al. “Bubble Curtains Attenuate Noise from Offshore Wind Farm Construction and Reduce Temporary Habitat Loss for Harbour Porpoises.” Marine Ecology Progress Series, vol. 580, 2017, pp. 221–237., doi:10.3354/meps12257.

When killer whales (Orcinus orca), also known as orcas, are mentioned the first thing people think of is SeaWorld. Orcas being very social animals that usually travel in pods with anywhere from 5 to 100 orcas, placing these whales in captivity does not allow them to socially travel with other orcas. These whales in captivity “cannot swim one hundred miles a day, breed and care for their young, socialize in kinship communities, play freely, hunt at will, or die of old age” (Schutten & Burford 2017). Taking any animal out of their natural habitat for educational benefits does not justify imprisoning them, their natural behavior will not be observed and learned, the adaption to living in a fishbowl is what will be learned. The second we take those whales out of the ocean they become prisoners. The largest captive whale weighed 12,500 pound and measured 22 feet in length, his name was Tilikum and he spent his thirty-five years of life in captivity living his days and nights in a tiny swimming pool.

Tilikum is one of the most known killer whales for his starring role in Blackfish. To SeaWorld, Tilikum was a breeder, trainers manipulated him sexually to collect his sperm to produce more captive born calves to train and sell. With being held in captivity for more than thirty years, performing Tilikum was bound to become agitated and aggressive not just towards the other whales in the tanks but towards the trainers too. Food was used as a reward, perform as the trainer wants and fish will be rewarded. These whales in captivity are completely dependent on the trainers to provide them with basic needs of survival: food and water. Orcas that live in capacity are not only mentally affected they are physically affected too. All adult male dorsal fins collapse, which can be a result of not having enough space to swim and their unnatural diets.   Tilikum reached a point where he became so aggressive and killed three trainers.  In 1991 trainer Keltie Byrne was pulled underwater and ultimately drowned, in 1999 Daniel P. Dukes was drowned and it was not until 2010 when Dawn Brancheau was dismembered and drowned that his actions were taken seriously. After the death of Dawn, Tilikum was placed in a tiny isolated enclosure where there was minimal space to swim, and no communication with other whales or interactions with humans. Captive whales have a much shorter life expectancy than whales in the wild. In January 2017 Tilikum passed away of a bacterial pneumonia.

Tilikum was not the only killer whale to lash out at trainers; SeaWorld has documents of over 100 incidents of injuries trainers obtained from agitated whales. Kasatka, another orca, repeatedly pulled trainer Ken Peters underwater by the leg during a live show. The death of trainers caused by whale aggression led to protests for SeaWorld to release the captive orcas back into the wild. Tilikum has been said to be a martyr for his cause, calling attention to the fact that if an animal is used for entertainment there will be consequences. As of March 2016 SeaWorld officially ended captive orca breeding, the orcas they have are the last orcas SeaWorld will have. In California live shows will be phased out.

For more information, check out the original scientific paper:

Julie “Madrone” Kalil Schutten & Caitlyn Burford (2017) “Killer” Metaphors and the Wisdom of Captive Orcas, Rhetoric Society Quarterly, 47:3, 257-263, DOI: 10.1080/02773945.2017.1309911

Marine mammals are fun to observe (from a safe distance) in their natural habitat. But there’s one aspect of their lifestyle we don’t often get a chance to see. What is that you ask? Hunting for food. It’s difficult to observe what exactly marine mammals eat because they dive into the deep water to hunt for food. Therefore, to understand what the diet of a marine mammal looks like, other methods need to be used. Having an understanding of what types of fish and other prey marine mammals consume can help with fishery and marine policy management. In order to get a better understanding of the marine mammal diet, you also need to know how much they’re eating in a given time. A group of researchers set out to collect data in order to find the diet composition and consumption rate of harbor porpoises’, a common marine mammal, in the western Baltic Sea.

In this study, Andreasen et. al (2017) spent 32 years collecting samples and data from harbor porpoises. These porpoises were already dead—either from stranding (becoming stuck on beaches) or from net entanglement. A total of 339 harbor porpoise stomachs were sampled (Andreasen et. al, 2017). Now in most cases, the porpoises’ last meal was already digested, but a key part of the food was still left in the stomach. What is that part exactly? The ear bone. That’s right folks, fish do in fact have ear bones— which are actually called otoliths. Otoliths are unique, which means a fish species can be identified by its ear bone. The researchers compared the otoliths they collected from the porpoises’ stomachs to those in a collection of 50 identified otoliths of various fishes. The researchers found that cod, herring, and gobies were the main prey for harbor porpoises in the western Baltic Sea. For adults, their diet consisted more of cod and herring, while juveniles also preyed on gobies (Andreasen et. al, 2017).

Overall, the researchers found their results matched the results of previous studies done on the diet of harbor porpoises in the North Sea and other nearby areas (Benke et al. 1998, Santos and Pierce 2003, Jansen et al. 2013, Leopold 2015). This said, if harbor porpoises are consuming mostly cod and herring, those fisheries will need to adjust their management in order to take into account how much the porpoises are taking from the stocks. This would help keep the cod and herring stocks from decreasing rapidly and being unable to recover.

For more information, check out the original scientific paper:

Andreasen, H., Stine, R., Siebert, U., Andersen, N., Ronnenberg, K., & Gilles, A. (2017, May 31). Diet composition and food consumption rate of harbor porpoises (Phocoena phocoena) in the western Baltic Sea. Marine Mammal Science, 33(4), 1053-1079

The Gulf of Maine is full of recreational and commercial vessels but is also home to the southernmost feeding ground of Humpback Whales. This overlap of human activity and primary feeding ground for whales means that at some point, a boat and whale will unfortunately cross paths. Collisions with whales have been an important factor impeding the rebuilding of the protected humpback whale population but sadly, there are no current regulations in place to reduce the likelihood and frequency of collisions except for whale watching vessels.

Because boat strikes on whales go underreported in Maine, Alex Hill and five other conservationists and biologists decided to find out how many humpback whales have collided with vessels in the Gulf of Maine. The group of scientists analyzed 210,733 high resolution images of 624 humpback whales, which were used for identification purposes by the Whale and Dolphin Conservation from 2004-2013, in order to determine how many of the individuals show signs of boat collision injuries. Similar studies have used this method to successfully evaluate the entanglement frequency of humpback whales in the Gulf of Maine.

The results of the study showed that 92 of the photographed whales (14.7%) have injuries consistent with those from collisions with vessels with some individuals having 2-4 injuries across their bodies. These results are underestimated considering strikes resulting in blunt force trauma or mortality could not be detected, the percentage is possibly much larger.

This study also discovered that adult humpback whales are much more prone to injuries from collisions with vessels given the frequency of injuries is higher for adults than calves and juvenile whales. Hill’s study states that foraging behavior could be the cause of the high frequency of adult whale collision injuries. The study cites Weinrich et al.’s 1997 study which discovered that adult humpback whales tend to capitalize on prey found in the upper water column, which could be why vessel strikes are so prevalent.

The humpback whale population has been growing recently due to conservation efforts, however, these efforts must continue in order to ensure the success of many marine mammal species. In 2008 the National Marine Fisheries Service (NMFS) implemented vessel speed restrictions in order to decrease the frequency and severity of boat collisions with North Atlantic Right whales. These speed restrictions were created to protect the right whales but were said to offer additional protection to humpback whales however, humpback whales did not see any significant benefit or protection.

In order to reduce the frequency of whale collisions with vessels, public education campaigns such as the “See a Spout, Watch Out!” campaign which was developed by Whale and Dolphin Conservation with the help of the National Oceanic and Atmospheric Administration (NOAA). These campaigns help educate boaters about the significance their presence in the Gulf of Maine can have on the beautiful wild life. Education and outreach campaigns are great for educating the public but Alex Hill recommends restrictions and regulations on vessels operating in known whale habitats in order to protect the humpback whales and other marine mammals in the Gulf of Maine.

For more information, check out the original scientific paper:

Hill, A. N., Karniski, C., Robbins, J., Pitchford, T., Todd, S. and Asmutis-Silvia, R. (2017), Vessel collision injuries on live humpback whales, Megaptera novaeangliae, in the southern Gulf of Maine. Mar Mam Sci, 33: 558–573. doi:10.1111/mms.12386

Just like Dorothy reminded us in The Wizard of Oz, there’s no place like home. As a new study suggests, Blainville’s beaked whales off Portugual’s Madeira Archipelago in the northeast Atlantic seem to think so, too.

In the study by Ana Dinis of the Center of Marine and Environmental Research of Madeira, she and her colleagues used photographs taken from whale-watching boats between 2004 and 2016 off the Madeira Archipelago in order to find out if there were any patterns of site fidelity.

Site fidelity is a term simply used to describe if an animal will tend to return to or remain in a particular area over a period of time. Understanding Blainville’s beaked whale site fidelity is especially important because of their high sensitivity to human disturbances, like noise. Manmade noises, like those emitted from naval sonars, are known to change the behavior of beaked whale species. They leave the area where there is noise disturbance, sometimes stop eating, and in severe cases become stranded (or stuck) on a beach and die.

There was evidence of both short-term and long-term site fidelity for these whales. Site fidelity was short-term when an individual whale was seen many days in the same area during the year, and long-term was when an individual was seen on multiple days over many years. This is one of the first studies to successfully show that there is site fidelity of the Blainville’s beaked whale off the Madeira Archipelago.

What makes the waters off the Madeira Archipelago such an important habitat for Blainville’s beaked whales? Scientists believe that it offers different benefits for each sex. Females rely heavily on the area primarily to feed, while males rely mainly on the groups of females that cluster there for opportunities to mate.

A notable case of a Blainville’s beaked whale stranding occurred on the Canary Islands in 2002. This stranding event was linked to sonar use in the area. Although there has been no evidence of Blainville’s beaked whale strandings on the Madeira Archipelago yet, in 2000 a similar species, Cuvier’s beaked whales, stranded there likely because of naval sonar use.

This study should shed light on how important the Madeira Archipelago waters are to Blainville’s beaked whales, demonstrated by their site fidelity. Hopefully policymakers will take this information and use it to better regulate the planning of military sonar practice in the vicinity of this important habitat. Minimizing the amount human-produced noise disturbance will likely prevent a devastating stranding event of Blainville’s beaked whales in this essential habitat off the Madeira Archipelago.

For more information, check out the original scientific paper:

Dinis, A., Marques, R., Dias, L., Sousa, D., Gomes, C., Abreu, N., and Alves, F. “Site Fidelity of Blainville’s Beaked Whale (Mesoplodon densirostris) off Madeira Island (Northeast Atlantic).” Aquatic Mammals. Vol. 43, no. 4, 2017. pp. 387-390

Humpback whales are best known for breaching out of the water, and their beautiful melodious songs that consist of cries, moans, and howls. This species of whale is often a favored subject for whale watches around the globe.

Unfortunately, ship strikes may be inhibiting the recovery of the North Atlantic humpback whale population. To address this question, a team of scientists studied humpback whales in the Gulf of Maine. This region has an overlap between humpback whale territory, and high commercial and recreational ship activity. There have been frequent reports of whales that appear to have been injured by ship strikes. However, these reports are typically after the injuries have occurred, with no knowledge of where and when they originated.

The team of scientists organized by Alex Hill, used over 200,000 high resolution photos collected from research and commercial whale-watching boats. It was determined that 624 individual humpback whales could be identified from the photos, where 92 showed injuries. Scientists examined the photos to determine injuries that resulted from ship strikes, and how often these injuries occur. An injury was determined by the appearance of physical trauma to a whale, such as cuts and damaged fins. The severity of each injury was also able to be determined based on the state of healing. Adult humpback whales have the highest risk for being injured by a ship strike due to their larger body size compared to when they are young.

There’s been a problem with people not reporting whales struck by ships. Researchers are not sure why people are neglecting to report whale strikes, but it likely has to do with a fear of getting in trouble for the event. The ultimate conclusion was ship strike injuries may have a potential role in the slow recovery of the humpback whale. Especially, where there are no current regulations by the government to prevent humpback whale strikes by ships. However, there are ship regulations for the highly endangered North Atlantic Right Whale that have been suggested to benefit other whale species. The National Marine Fisheries Service enforce speed regulations during the season that the Right Whales are present in the Gulf of Maine. Ships must keep a speed of 10 knots or less in these areas from January-July. Unfortunately, a study found that these regulations do not significantly benefit humpback whales, and that they continue to occasionally be struck by ships.

At the time of this study, which occurred from 2004-2013, humpback whales were listed as endangered throughout their range. The good news is, humpback whales were removed from the endangered species list just last year in 2016. However, care needs to be taken to prevent the re-listing of one of societies favorite whale species.

For more information, check out the original scientific paper:

Hill, A, N., Karniski, C., Robbins, J., Pitchford, T., Todd, S., Asmutis-Silvia, R. 2017. Vessel collision injuries on live humpback whales, Megaptera novaeangliae, in the southern Gulf of Maine. Marine Mammal Science. 33(2): 558-573.

Humpback Whales were added to the endangered species list in 1970, driven close to extinction through years of commercial whaling. The majority of humpback populations are now rebounding thanks to the US Endangered Species Act, the US Marine Mammal Protection Act, and the International Whaling Commission. The combination of these regulations has helped to protect humpback whales as well as many other species and has essentially put a stop to the commercial whaling industry. However, these increased population sizes may also be a contributor to an increased number of whale and boat interactions. This is especially true in the Gulf of Maine, in which the humpback whales’ primary feeding ground and feeding time overlaps with recreational and commercial boating activity in the area. The large majority of these ship strikes go unreported, and until a recent study by Alex Hill and her colleagues, it was unknown just how many whales were affected by vessel collisions in this region.

This recent study, published in Marine Mammal Science, looked at high-resolution whale photographs taken by Whale and Dolphin Conservation to determine the impact of vessel strikes in the Gulf of Maine. Looking at over 200,000 photographs of 624 individual whales, multiple reviewers determined that approximately 14.7% of the photographed whales had been struck and injured by at least one boat. Severity of the wounds and stage of healing were also scored by the reviewers; they concluded that the majority of wounds were still in the healing process and were most often categorized as deep wounds penetrating the blubber.

This may seem like a low percentage to some, but it is important to realize that these results do not include those whales killed by vessel interactions and therefore only provide us with part of the story. A study by van der Hoop and colleagues found that the large majority of dead humpback whales are a result of human activities. Therefore, we should only consider the number of injuries as an indicator of how large of an impact we are potentially having on this species.

Apart from whale watching activity guidelines, there are currently no regulations designed to reduce humpback whale and vessel interactions. However, the results of this study suggest that measures need to be taken to reduce the number of vessel strikes upon humpback whales in the Gulf of Maine. Regulations could potentially allow the humpback whale population to continue to rebound as well as reduce human caused injuries and fatalities of the species.

Seasonal regulations have already been put into place in the area to protect the North Atlantic Right Whales, and have appeared to reduce the number of collisions. Therefore, there is hope that more regulations involving all vessel types may help decrease ship collisions with humpback whales in the Gulf of Maine.

For more information, check out the original scientific paper:

Hill, A. N., Karniski, C., Robbins, J., Pitchford, T., Todd, S. and Asmutis-Silvia, R. (2017), Vessel collision injuries on live humpback whales, Megaptera novaeangliae, in the southern Gulf of Maine. Mar Mam Sci, 33: 558–573. doi:10.1111/mms.12386

Manatees are herbivorous, free swimming, gentle giants that enjoy warmer climates and water temperatures. Historically hunted almost to extinction, today the species continues to face threats such as illegal overfishing, drowning while entangled in fishing nets, and changes to their habitats. These marine mammals are part of the order Sirenia. Sirenians are broken down into two families, the Trichechidae that include manatees, and the Dugongidae that include dugongs. Earlier this year, the West Indian manatee was classified as threatened with extinction by the Convention on International Trade in Endangered Species (CITES), and the Secretaria del Medio Ambiente y Recursos Naturales (SEMARNAT), and as vulnerable by the International Union for Conservation of Nature and Natural Resources (IUCN). Unfortunately, these innocent creatures have been dwindling in numbers and if no efforts of mitigating these threats are taken, the population may not recover.

Recently, researchers studying the West Indian manatee (Trichechus manatus) populations in Mexico reported on the devastating condition for this species. Only 121 manatees remain along the Alvarado Lagoon System (ALS) in the state of Veracruz, where past estimations place manatee populations to approximately 1,000 to 2,000 individuals. In the state of Quintana Roo, another once heavily populated area, the careful tracking and surveying of the manatees has concluded that approximately 250 manatees remain in this region (Serrano et al. 2017). West Indian manatees mostly like to congregate in these areas of warm waters and an abundance of food supply, thus making this the perfect spot to survey and estimate the current remaining population statistics.

Manatees truly are gentle giants as they do not compete with one another for food, other resources, or mating. As herbivores, they only eat sea grasses and other various algae. Human interference is a major cause of population declines as the only predators that face manatees are humans. Factors such as boat strikes, entanglement from fishing nets, ocean acidification, pollution, hunting or overfishing, and changes in the climate (which affect their habitats) are major influences that are causing recent population declines.

Utilizing a combination of visual, acoustic, and sonar techniques to count the manatees in the wild, the research team led by Dr. Serrano and colleagues was able to estimate the population density of the West Indian manatee in the ALS. During the research period between October 2008 to January 2011, they observed only 13 manatees. Researchers found that the species is slowly relocating or disappearing from the state, and that population size continues to plummet. They cannot help but conclude that the future local extinction of this mammal is upon us, as has already been observed in other regions of Mexico. That is why long-term observation and conservation is crucial for the survival and repopulation of this cherished manatee.

For more information, check out the original scientific paper:

Serrano, A., del Carmen Daniel-Rentería, I., Hernández-Cabrera, T., Sánchez-Rojas, G., Cuervo-López, L., & Basáñez-Muñoz, A. (2017). Is the West Indian manatee (Trichechus manatus) at the brink of extinction in the State of Veracruz, Mexico?. Aquatic Mammals, 43(2), 201.

As the health of the environment declines, more and more methods to combat negative effects of human impacts are being designed and implemented throughout the globe. But can some these modern technologies actually harm animals?

Offshore wind turbines are designed to create renewable energy and reduce harmful gas emissions. These sounds like beneficial effects, however, constructing wind turbines in the environment of marine mammals is bound to have an impact them. If the impacts on marine mammals are detrimental, at what point do the costs outweigh the benefits?

In a study conducted by Vallejo et al., researchers observed harbor porpoises in an area surrounding the Robin Rigg offshore wind farm, located in the Solway Firth in the northern Irish Sea. This is a vital habitat for harbor porpoises. Observations were made in the preconstruction, construction, and operational phases in the development of the farm. Observations were made by individuals from elevated viewing platforms on boats, with the help of high-quality binoculars. The abundance of harbor porpoises present in the area is a good indicator of the degree of the impact the wind farm has on these animals. While observing the porpoises in the preconstruction phase, researchers learned how many porpoises resided in the area. They then observed and counted the number of porpoises present in the construction and operational phases of the farm, to see if the abundance of porpoises changed significantly. If it had, the assumption that the wind farm had a severe and negative impact can be made. The goal of the researchers was to observe and measure the severity of the impact the development of wind turbines has on this species, and whether the effects are detrimental.

The study revealed that no significant difference in the abundance of harbor porpoises was found between the preconstruction and operational phases of the wind farm. However, a significant decrease in the number of these animals occurred in the construction phase of development. This is due to the noise pollution that is brought about by loud construction methods such as pile driving. These animals fled the area due to this noise pollution, but returned to the preferred habitat once construction ceased and the noise pollution ended as well.

The findings from this study tell us that wind farms do not have a considerable impact on marine mammals such as harbor porpoises. The construction of them, however, does have short term consequences in which quality habitat can be abandoned. This can be harmful to the species if they relocate to a habitat that is not as well suited for them as the one they left, even if it is only temporarily.

Sources of renewable energy such as wind turbines and marine mammals can coexist, if the construction phase is not too invasive on the marine ecosystem. To minimize the negative impacts on marine mammals, construction of offshore wind turbines should be done as quickly as possible, with methods designed to lessen the severity of noise pollution and disturbance to the surrounding habitat.

For more information, check out the original scientific paper:

Vallejo, Gillian C., et al. “Responses of Two Marine Top Predators to an Offshore Wind Farm.” Ecology and Evolution, vol. 7, no. 21, 2017, pp. 8698–8708., doi:10.1002/ece3.3389.

Human exposure may be making harbor seals less responsive to predators in the Salish sea. A study conducted by Olsen and Acevedo-Gutierrez (2017) studied harbor seals at low, medium and high human exposure levels, within San Juan Islands and southern Puget Sound of the Salish Sea in Washington. The human exposure levels were established based on the amount of boat traffic that was present around an area where seals tend to gather onshore. Their observations of harbor seal response, to the presence of a bald eagle predator at six study sites (2 low exposure, 2 medium, and 2 high) indicate that the seals are starting to become accustomed to human presence. As a result the seals are not as responsive to a predatory threat. Six behaviors of the bald eagle predator were observed, gliding, powered flight, landed, scavenging, and attack, in conjunction with three harbor seal behaviors. The three types of behavior observed for seals were, no reaction to predators, alertness, and flushing. Flushing occurs when a seal may be frightened on shore or feel threatened and moves to the water for safety. Olsen and Acevedo-Gutierrez found that seals at the high human exposure sites were less responsive to the presence of bald eagles than those at low exposure sites, and exhibited less alertness and flushing. They believed that this was because the seals at the high human exposure sites may be becoming less sensitive to the presence of unfamiliar things, like new sounds or objects. In essence the harbor seals are becoming lazy when it comes to responding to potential threats. Harbor seals’ increase to human tolerance is important in understanding how humans impact the activity of the seals as it may make them more vulnerable to predation. The researchers did acknowledge that further studies looking at the proportion of adults, juveniles, and pups at seal resting locations on shore would help to further our understanding in human impact on seal predator response, as the presence of pups may cause the seals to be more alert. Nonetheless, the findings of Olsen and Acevedo-Gutierrez (2017) are important in determining how human presence effects harbor seal risk of predation. In addition, the study helps us to recognize how important it is for us to understand how humans impact natural predator-prey relationships.

For more information, check out the original scientific paper:

Olson, J.K., Acevedo-Gutiérrez. 2017. Influence of Human Exposure on the Anti-Predator Response of Harbor Seals (Phoca vitulina). Aquatic Mammals. 43(6): 673-681

You might not think that injury and death from gunshot would be a significant risk to seals and sea lions, especially since harming them is strictly prohibited. But as it turns out it, it is all too common.

In a study recently published in the journal Marine Mammal Science, a team of researchers analyzed marine mammal stranding reports on the central Californian coast for a 12-year period from 2003-2015, to categorize what most puts them at risk. Gunshots, they found, are a major contributor. Just to take a step back, a stranded animal is one which is outside of its natural habitat, and potentially at risk of death. With well over 10,000 reports of stranded marine mammals, lead author Daniela Barcenas-De la Cruz, from The Marine Mammal Center, and the other researchers focused their attention on those stranded animals that suffered from anthropogenic trauma – that is, from injury attributed to humans.

617 animals, or 6% of all strandings suffered from some type of anthropogenic trauma. These types were categorized as gunshot; fishing tackle, which included the presence of a hook, lure, or pot; boat collision; and marine debris, or trash.

“Marine debris has become the most common anthropogenic interaction in the past years,” said Barcenas-De la Cruz. This surprised the authors, who fashioned the study to match a previous study from the late 1980’s and early 1990’s by Tracey Goldstein. “We figured it will be practical to give it some continuity and make the data comparable by using the same criteria.” This way, not only could they look at what forms of trauma most affected the seals, sea lions, dolphins and whales that strand in their study area, they could also analyze how these causes have changed over time. With the exception of gunshots, which decreased over time, every other source of anthropogenic trauma increased from the first study to the second.

The other thing that most surprised Barcenas-De la Cruz and her collaborators? “The high prevalence for Guadalupe fur seals, since they are not residents of the area. It will be interesting to know what is going on in their usual habitat that is making us see them more in non-usual locations.” Given the habitat shift, she does not at this point know where they are becoming entangled – are they finding the debris in California or bringing it with them from Mexico. Answering questions like this could have real management implications for this species and others.

In addition to the mystery of the Guadalupe fur seals, which is one area where they hope to see further research, Barcenas-De la Cruz sees other potential management implications from the data collected. Marine mammals are very visible indicators of marine health, and can help illuminate the impact humans are having on the marine ecosystem. “I hope it can also make us realize how our activities are making an impact in the marine mammal populations and to look for better alternatives.”

For more information, check out the original scientific paper:

Barcenas-De la Cruz, D., DeRango, E., Johnson, S.P., Simeone, C.A. (2017). Evidence of anthropogenic trauma in marine mammals stranded along the central California coast, 2003-2015. Marine Mammal Science, doi:10.1111/mms.12457.