Marine Mammals in the News

Killer whales, or Orcinus orca, are one the most notorious ocean predators on the planet, famous for their black and white coloration and group hunting techniques. While ordinarily they would be expected to be a danger to the smaller dolphins and porpoises that share their waters, a study by Brittany Visona-Kelly and Lance Barret-Lennard has shown that these species have found peace with each other, and can even offer some benefit to each other.

From 2018 to 2021 drones were used to record high quality images and videos of resident killer whales in the Northeast Pacific, and in many of these recordings it was found that often times Dall’s porpoises (Phocoenoides dalli) and Pacific white-sided dolphins (Lagenorhynchus obliquidens) were nearby. These resident killer whales, while major predators, do not actively consume marine mammals, while traveling killer whales from elsewhere still may. By analyzing the behavior of the killer whales, Dall’s porpoise, and Pacific white-sided dolphins for situations where the species were within 200m of each other, the conditions for these interactions were able to be categorized.

It was found that between the species that Dall’s porpoise would interact with smaller groups of killer whales (≤5 killer whales) while Pacific white-sided dolphins would interact with larger groups of killer whales (≥25 killer whales). These interactions are initiated by the porpoise or dolphin and usually involve swimming in close proximity to the killer whales, who largely ignore the presence of the smaller species. It is believed that the reason the porpoise and dolphins are willing to move so close to the killer whales is that their presence naturally scares away other transient killer whales that are more likely to attack them, and that by swimming together the species create more beneficial slipstreams, which aid them both in swimming. The risk of the killer whales attacking is worth it to the smaller species, who can avoid all other predators thanks to the killer whale’s tolerating their presence and primarily hunting different species.

This study sets a fascinating idea for how predator and prey species may be interacting outside of our current understanding. It speaks to the importance of understanding the deeper dynamics between marine species. Because of these unique circumstances we now know that dolphins and porpoises in the Northeast Pacific are able to identify resident killer whales which do not hunt marine mammals and benefit from their warding of predators and slipstreams. These hidden dynamics can provide more reason for us as observers to try and maintain balance in the climate and ocean, as we never know what changes could break apart these important relationships between species.

For more information, check out the original scientific paper:

Visona-Kelly, B.C. & Barrett-Lennard, L.G. (2025). The foe you know: Observations of interspecific interactions between small cetaceans and northern resident killer whales (Orcinus orca) in the Northeast Pacific. Ecology and Evolution. 15:e71444. https://doi.org/10.1002/ece3.71444

Every year, thousands and thousands of tourists go to the coast of Argentina hoping to see Southern right whales up close. But as whale watching gets a larger audience, so does the question about whales livelihoods. Are boats causing harm to what they’re watching?

A new study published in Marine Mammal Science shows some answers about this problem. Researchers in Bahia San Antonio, a marine mammal protected area in northern Patagonia, show how southern right whales change their behaviors when they are being watched by whale watching vessels. The scientist built a model to measure how boat presence might change the whales “activity budget” or how they separate time between important behaviors like resting, socializing and their surface activity.

Nearby boats altered a certain type of whale behavior the most, which was surface active behavior. This includes breaching, rolling and flipper slapping. These whales tended to spend less time on this behavior when vessels were close to them. However the study also showed that the level of whale watching happening in the area currently stays below the threshold where these changes become biologically harmful. The whales are reacting, but not in a way that would threaten their health or overall survival.

What the scientists found was a good thing because places where whale watching happens usually support local communities. The study comes with a message stating that these activities are only sustainable if they stay within safe limits. They used a model they made to calculate “exposure thresholds” , which means how much time whales can spend near boats before their behavior changes too much. These limits can help people set rules to try to control the amount of boats and the length of time the boats are out.

This study points out many times that what they found is for the conditions currently in Bahia San Antonio. Increased tourism, changes in whale population or different types of boats could all change the reaction of the whales. The study also states that keeping track of whales long term will be extremely important to make sure that whale watching stays enjoyable for people and safe for whales.

This research study gives a science based guide for tourism in Argentina. When whale watching is managed carefully, it can continue to connect humans to wildlife without putting them in danger.

For more information, check out the original scientific paper:

Arias, M., Dans, S., Crespo, E.A., & González, R.A.C. (2025) Southern right whale behavioral changes due to interactions with whale-watching vessels: evidence-based calculations aimed at improving management policies. Marine Mammal Science, 41: e13149. https://doi.org/10.1111/mms.13149

Baleen whales like the Humpback, Blue, and Right whales, are the gentle giants of our oceans, migrating huge distances and singing their unmistakable songs that can be heard for miles. They are, however, often the primary target for one of the oceans most dangerous predators, the killer whale. What if the threat of this voracious predator has a bigger part to play in how baleen whales behave and communicate than previously thought?

A recent study found that broadly, baleen whales can be broken into two groups; “Fight”, and “Flight”. It was found that these two groups are separated both by their behavior when confronted with a threat like killer whales, but also in their physical appearance. Fight species ( North and South Atlantic Right whales, Humpback whales, Gray whales, etc.) use active, often coordinated group defense against killer whale attacks, while flight species (Blue whales, Fin whales, Sei whales, etc.) take advantage of their long, streamlined body to flee as fast as they can for long period of time in one direction, often doing little to defend themselves if they are overtaken and attacked by the predatory killer whales.

In this study, it was found that almost all “fight” species produce sounds that are easily detectable by killer whales, sometimes making sounds detectable from over ten kilometers away. “Flight” species on the other hand, are all “acoustically invisible” to killer whales, producing sounds loud enough to communicate with one another, but at a low enough frequency that it is undetectable by killer whales. This is known as “acoustic crypsis”; a behavioral strategy used by whales to avoid detection. There is substantial evidence to support the hypothesis that flight species are more acoustically cryptic than fight species, suggesting that interactions with killer whales have shaped their behavior and communication strategies to avoid confrontation and
attacks as much as possible.

This hypothesis has reshaped our own understanding of how baleen whales communicate, and sheds light on some of the social intricacies of that communication. Ultimately, this theory begs the question of whether environmental pressures like killer whale predation similarly shape and change other aspects of marine mammal behavior beyond communication.

For more information, check out the original scientific paper:

Branch, T.A. (2025) Most “flight” baleen whale species are acoustically cryptic to killer whales, unlike “fight” species. Marine Mammal Science, 41: e13228. https://doi.org/10.1111/mms.13228

Picture this: It’s a beautiful day off the coast of Argentina. Dozens of tourists crowd around the railing of a whale-watching boat to catch a glimpse of a massive Southern Right Whale, Eubalaena australis. But what is this interaction like for the whale?

With whale-watching expeditions gaining global popularity, generating $2.1 billion in revenue per year, some conservationists frame whale-watching as “consumptive exploitation” of an endangered species. Ecotourism, including whale-watching, brings copious benefits to coastal communities, including economic and infrastructural growth. However, scientists recognize the need to base further development of the practice on effective management processes, balancing tourism and conservation to minimize negative impacts.

One team of scientists led by Magdalena Arias, a scientific researcher at the National Council for Scientific and Technical Research of Argentina, evaluated the potential behavioral changes caused by whale-watching interactions in Southern Right Whales. Researchers in the Bahía San Antonio Marine Protected Area recorded the behavior of individuals between August and October over a 10-year period from 2014 to 2023. Data was taken throughout the breeding season, when the whales were active in the area, but initial condition and feeding success throughout the season could not be effectively monitored.

Between research and commercial trips, observers collected information on apparent social structure and individual behaviors, categorized as surface activity, travelling, resting, social activity, or underwater activity. The research team quantified whale behavior, which made it possible to create a theoretical model to determine how often and for how long whale behavior was disrupted when whale-watching vessels were present. Researchers determined the level of exposure an individual could sustain without significant behavioral disruptions, calculating vessel-exposure thresholds. Above this threshold, individual activity is altered in a manner that may have long-term consequences on health, growth, and reproduction. The study does not, however, consider the combined impact of stress from multiple disturbance sources, such as other vessels, fishermen, and kayakers.

While surface activity like breaching and tail slaps were the most affected behaviors, the overall vessel exposure observed in the Bahía San Antonio Marine Protected Area stayed below the threshold that would cause significant behavioral changes. The researchers ultimately concluded that whale-watching activities in this area were sustainable, having no biological impact on the individuals studied. Thresholds determined by the scientists can be used to inform limits on whale-watching practices as the industry continues to grow, ensuring this enjoyable experience can continue for generations to come.

For more information, check out the original scientific paper:

Arias, M., Dans, S., Crespo, E.A., & González, R.A.C. (2025) Southern right whale behavioral changes due to interactions with whale-watching vessels: evidence-based calculations aimed at improving management policies. Marine Mammal Science, 41: e13149. https://doi.org/10.1111/mms.13149

In the chilly waters off southern Iceland, scientists have recently witnessed something that challenges our assumptions about one of the ocean’s top predators. Killer whales, famous for their coordinated hunts and powerful attacks, were seen interacting not with adult prey, but with newborn long-finned pilot whales, and in surprisingly gentle, complex ways. These rare events, described in a new study published in Ecology and Evolution, raise fresh questions about how cetaceans (whales and dolphins) communicate, play, and sometimes clash in the wild.

Researchers documented two encounters, one in June 2022 and another in June 2023, where a lone neonate (newborn) pilot whale calf appeared among groups of killer whales. No adult pilot whales were present, an unusual and potentially risky situation for such young animals. Yet what unfolded wasn’t straightforward predation. Instead, the killer whales, mostly known fish-eaters, shifted between foraging, socializing, and repeatedly approaching the calves in ways that didn’t clearly signal aggression. The calves often surfaced in echelon position next to adult female killer whales, a behavior young animals usually show with their own mothers. In some instances, killer whales even appeared to nudge or lift the calves, keeping them at the surface.

So what was happening? The researchers considered several possibilities. One is play behavior, a surprisingly common feature among dolphins and whales, especially younger individuals. Another hypothesis is practice hunting, where killer whales use other species to refine group coordination and predatory skills, something previously documented in other regions. A third possibility is epimeletic behavior, or misplaced caregiving, where killer whales may respond to a vulnerable calf even if it is not their own.

Yet the true explanation remains mysterious. Observations of each event were limited in duration, and crucial context, such as how the calves became separated from their pilot whale groups, was never witnessed. In one case, the calf was lifted out of the water shortly before researchers had to leave due to weather, and in both years, the calves were never seen again.

These unusual interspecies encounters highlight just how much remains unknown about cetacean behavior. They also underscore the importance of documenting rare events: each new observation helps researchers better understand how whales interact, communicate, and sometimes blur the line between friend, foe, and something in between.

For more information, check out the original scientific paper:

Baumgartner, C. D., Selbmann, A., Middel, H., Schulze, J., Bellon, G., & Samarra, F. I. (2025). Interactions between killer whales (Orcinus orca) and neonate long‐finned pilot whales (Globicephala melas) off South Iceland. Ecology and Evolution, 15(4), e71193. https://doi.org/10.1002/ece3.71193

Each year, thousands of baleen whales migrate from their summer Alaskan feeding grounds to tropical Hawaiian waters to raise their calves. This pilgrimage is made by blue, humpback, gray, and right whales from nutrient-rich cold waters to their preferred waters for birthing. These filter feeders prefer feeding in more Arctic latitudes, because their preferred prey lives there. When it comes to raising calves though, tropical waters are more favorable because of the lack of natural predators. While the migration these gentle giants make is remarkable on its own, recent research shows they may actually be making the environment around them healthier throughout their journeys.

Tropical environments often have low nutrient levels, but whales may be a key to increasing these depleted resources in their breeding grounds. Marine biologist Joe Roman has documented the natural byproducts of whales and their impact on local ecosystems. Roman specifically looked at shedded skin, extra milk released, excreta (urea and feces), and carcasses. The cumulative amount of biomass (organic matter) transported from wintering grounds to summering grounds was found to be a whopping 46,512 tons; a statistic that also transported an additional 4,874 tons of carbon and 3,784 tons of nitrogen to the tropics. Roman describes this phenomenon as the Great Whale Conveyor Belt. These whales play a key role in maintaining a thriving tropical ecosystem. In the tropics, the sun supercharges plankton photosynthesis which takes up a lot of carbon and nitrogen. It is important to keep plankton levels high because of how rapidly they are consumed by higher members of the food web. Whales help replenish the depleted nutrients which in turn helps keep plankton populations high enough to support healthy ecosystems.

To determine the full effects of whales, Roman compared the biomass of nutrients whales bring to how much the tropics naturally receive. Upwelling is the natural movement of water from the deep ocean to shallower depths. This movement can bring nutrient-rich water that infuses into the shallower environments. Roman found whales contribute 125-175% as much nitrogen to these ecosystems as natural upwelling does, meaning these whales are responsible for a very significant amount of nitrogen transfer. When whales die in tropical waters, their carcasses also feed several tropical animals like worms, crabs, and sharks. This food source is important in maintaining a healthy ecosystem, and in a nutrient-deficient tropical area, these whales can be the difference between a community of animals dying or living another day.

Roman also stresses the importance of conservation of these majestic creatures. He estimates whales would have been able to transfer three times the amount of nutrients they
currently do if populations matched pre-industrial whaling numbers. By investing in the conservation and protection of whales, ecosystems in tropical regions benefit. More nutrients means more growth and a more balanced thriving ecosystem. This research adds to the already long list of reasons to help conserve whale populations.

For more information, check out the original scientific paper:

Roman, J., Abraham, A.J., Kiszka, J.J., Costa, D.P., Doughty, C.E., Friedlaender, A., Hückstädt, L.A., Marcondes, M., Wetsel, E., Pershing, A.J. (2025). Migrating baleen whales transport high-latitude nutrients to tropical and subtropical ecosystems. Nature Communications, 16, 2125. https://doi.org/10.1002/ece3.71193

The name killer whale is notorious across the world, making people think of terrifying beasts with large mouths and sharp teeth; the only animal well known for hunting great white sharks. This picture in your head of a vicious killer (I mean, it’s even in the name) likely doesn’t involve any form of friendliness, but what if I told you that these creatures not only can play nice with others, but can even play nice with animals from other species? A paper written by Visona-Kelly and Barrett-Lennard (2025) “The Foe You Know” says just that.

Killer whales, or Orcas, are already known to have complex matriarchal pod structures, but even with these pod structures it is very unlikely to see Orcas getting along well with other species. This makes it even more surprising that Visona-Kelly and Barrett Lennard witnessed seemingly friendly “intraspecific interactions” (interactions between animals from different species) involving Orca pods and both Dall’s porpoises and Pacific white-sided dolphins.

Between 2018 and 2021, a drone project taking photos to identify Orca whales around the Johnstone Strait in British Columbia included photos of Dall’s porpoises and Pacific white-sided dolphins with the Orcas. The interesting part wasn’t that the
dolphins and porpoises were there, but that the Orcas didn’t seem to mind! The dolphins and porpoises tended to join the Orca groups while they were travelling, and the dolphins and porpoises were always the initiators of the
interactions. In fact, the dolphins and porpoises even were social with the Orca calves!

Changes in behavior (like speed and swimming formation) changed after the encounters for both dolphins and Orcas, but not for porpoises. The dolphins tended to swim alongside the Orcas or behind them, where porpoises tended to swim in front of or mingled into the Orca groups. “This is the first study to use drones to describe non-predatory interspecific interactions involving killer whales and small cetaceans (dolphins and porpoises),” says the paper.

Still, why are they together at all? Why are the smaller dolphins and porpoises seeking out Orca whales, and why are the Orcas letting them? One theory is “antipredation,” where the dolphins and porpoises are seeking out the resident Orcas because the while these pods only eat fish, they act as a deterrent to great white sharks, and the Bigg’s Orca pod, a group of orcas that is a predator of other mammals. Another is possible foraging advantages, where the hunting success of one species lets them share information on where the best catches are, and Orcas are known to socially share prey with one another.

Overall, while we don’t know for sure why the Orcas are making these friends, we do know that these animals with their killer reputations aren’t quite as killer as we might think.

For more information, check out the original scientific paper:

Visona-Kelly, B.C. & Barrett-Lennard, L.G. (2025). The foe you know: Observations of interspecific interactions between small cetaceans and northern resident killer whales (Orcinus orca) in the Northeast Pacific. Ecology and Evolution, 15:e71444. https://doi.org/10.1111/mms.13010

HPAI (Highly Pathogenic Avian Influenza) H5N1 is killing southern elephant seals at a concerning rate. Off the coast of Argentina, researchers at Peninsula Valdés have been monitoring the Patagonian colony of elephant seals for over 40 years. The goal of the study was to estimate the death rates in different scenarios. Unfortunately, the estimates were anything but pleasant.

Researchers used 5 scenarios to determine how the colony would be affected by the virus. While these numbers are mostly accurate, researchers cannot control certain variables. For example, any seals that die at sea will not be included in the count.  The first scenario was the baseline estimate. It used a specialized equation that helped researchers determine the estimated increase (as if no seals were affected by the virus) from the year 2022 onward. The projected increase was 0.9% per year. However, the next scenarios are where things start to get dire.

The second scenario aimed to determine what would happen to the population if all of the pups in the colony died from HPAI in the year 2023. The third scenario added a 50% adult mortality on top of that, then the fourth added on top of that scenario by simulating failed insemination the following year (2023), Finally, the fifth scenario combined all of these factors and added an additional component of 20% of the adults dying.

Overall, the population in each of these scenarios took roughly a decade (2033) to recover to the original population. However, the population can take several decades to recover if the virus consistently kills adults. Many will think that only one animal is being affected; however, several other animals are dying from this disease (aside from the birds). These animals include seals, dolphins, porpoises, otters, and polar bears.

If one animal goes extinct, the balance of an ecosystem changes severely, but if many animals of the same ecosystem go extinct, that ecosystem will soon cease to exist. While this disease is really only this prevalent in South America, because these are marine animals, it won’t be long before the infected animals (birds and others) migrate, and spread the disease even further. But for now, this disease is having a serious impact on Peninsula Valdés’s elephant seal population and should be addressed so that our oceans and its inhabitants stay safe. So, if anyone cares about the marine ecosystem, they should care about this epidemic.

For more information, check out the original scientific paper:

Campagna, C., Condit, R., Ferrari, M., Campagna, J., Eder, E., Uhart, M., Vanstreels, R.E.T., Falabella, V., Lewis, M.N. (2025). Predicting population consequences of an epidemic of High Pathogenicity Avian Influenza on Southern Elephant Seals. Marine Mammal Science, 41:e70009. https://doi.org/10.1111/mms.70009

As oyster farming expands along the coast of Alaska, concern has sparked among scientists and the public alike that these farms may create potential conflict with one of the ocean’s most endearing residents, the adorable sea otter. These marine mammals are not just known for their fluffy fur and cute faces; they are also known for their large appetites! Sea otters can eat up to 20-25% of their body weight and enjoy snacking on nearly 150 different taxa. With sea otters being yearly residents of Alaskan waters, oyster farms have had reason to worry! However, a recently published study brings surprisingly positive news on the relationship between oyster farmers and their fluffy friends.

Researchers spent two summers observing sea otters in and around several oyster farms in southcentral Alaska. Using high-tech telescopes and meticulous observation, they expected to see the otters dining at the all-you-can-eat oyster buffet. However, they observed the opposite: the sea otters showed little to no interest in the oyster farms whatsoever. Even more striking, the research team did not observe a single farmed oyster being eaten by a sea otter.

Several minor errors were also revealed in their study. They found that 39% of the otters’ diet was unidentifiable prey, so they couldn’t rule out the possibility of farmed oyster consumption. There was also one farm that grew mussels as well as oysters, on ropes in the water, which several otters were found snacking on, as they were more easily accessible. But, overall, the sea otters were observed sticking to their normal menu of clams, crabs, and wild mussels. Scientists monitored the otters’ foraging success, the number of prey items recovered, dive success, and several other factors. These observations were recorded at farm sites, non-farm sites, and reference areas, and the otter’s foraging success was roughly 90% in each. This suggests that the presence of oyster farms neither helps nor hinders the hunting habits of the sea otters.

These findings offer reassurance for both scientists and the growing aquaculture industry in Alaska. Right now, sea otters and oyster farms can coexist with little conflict, but the research team recommends continued observation of this sea otter population as well as others. As more coastal communities turn to aquaculture as a main source of food, research like this is vital to understanding the impact aquaculture farms have on the marine environment and vice versa.

While questions remain about potential impacts year-round, or in other regions, this study provides a promising glimpse of harmony between marine wildlife and the aquaculture industry along Alaska’s coastline. An encouraging step towards forming healthier relationships between humans and the marine environment.

For more information, check out the original scientific paper:

Reynolds, E., Konar, B., Horstmann, L. (2025). Sea otter interactions with mariculture oyster farms. The Journal of Wildlife Management, 89:e70055. https://doi.org/10.1002/jwmg.70055

Whales are one of the most recognizable creatures in the world, with some species being observed by people in completely different parts of the world. This is because whales migrate over thousands of miles, moving from food-rich northern feeding grounds to warm tropical waters where they give birth. Talk about traveling for the holidays!

While on these migrations, whales unknowingly bring with them nutrients, organic materials that are used in biological processes such as growth and photosynthesis, that are beneficial to their destination’s ecosystem. The whales gain these nutrients from foraging throughout their feeding grounds and deposit them in the calving grounds in the form of detritus (bodily waste such as urine, feces, and their carcasses when they die). But just how much are they transporting, and why does it matter?

A study looking to answer this same question by Joe Roman, a marine ecologist,  found that the entire populations of gray whales, humpback whales, and three populations of right whales transported about 46,512 tons of biomass (organic matter), 4,874 tons of carbon, and 3,784 tons of nitrogen per year from their feeding grounds to their calving grounds. To put this in perspective, a firetruck weighs about 4.5 tons, which means that about 10,336 firetrucks of biomass were transported to a new part of the world in just one year. This vastly outcompetes the amount of nutrients added to the ecosystem from natural processes such as vertical mixing, where surface water is replaced by water from below, bringing its nutrients with it. And that’s just three species! Imagine how much is transported by all migrating whales worldwide!

This answers how much are these whales transporting in their migrations, but why does this matter?

Overall, these nutrients fuel the food chain, providing food for all levels of the ecosystem. Nutrients from the urea and feces boost the concentrations of nutrients used by phytoplankton, plankton that photosynthesize like a plant, while the carcasses provide food for many predatory species such as the tiger shark and scavengers. Additionally, the nutrients taken up by the phytoplankton boosts activity, allowing for them to increase their own biomass in the form of multiplying their population sizes. This provides more food for small animals that feed on these plankton, which in turn provide food for their predators.

Clearly, whales play an important role in supplying these tropical ecosystems with the nutrients they need to survive, but it used to be so much more. Whale populations were depleted from commercial whaling in previous centuries, thus reducing the number of migrating whales and the amount of nutrients being transported. It is estimated that about three times the amount of nutrients were transported in pre-whaling times – and we thought the current numbers were huge! Unfortunately, even though many populations have begun to recover, future human activities may imperil whale populations again, throwing the ecosystems dependent on their nutrients into a famine.

For more information, check out the original scientific paper:

Roman, J., Abraham, A.J., Kiszka, J.J., Costa, D.P., Doughty, C.E., Friedlaender, A., Hückstädt, L.A., Marcondes, M., Wetsel, E., Pershing, A.J. (2025). Migrating baleen whales transport high-latitude nutrients to tropical and subtropical ecosystems. Nature Communications, 16, 2125. https://doi.org/10.1002/ece3.71193

Large northern populations of humpback whales travel lengths to make it to proper breeding grounds and feeding grounds, relying heavily on krill for that energy to make it back and forth. Making sure to keep track of whale migration allows scientists to make sure they are eating enough and being provided with enough food to survive that journey. Humpback whales living in the southern hemisphere are reliant on Antarctic krill for their daily caloric intake, which then converts into energy and helps them along on their tiring trip from Antarctica to Columbia. Using drones to take specific measurements to create helpful 3D models, these scientists were able to provide context for the change in body condition once they reach their destination and how whale populations hang in the balance of krill populations.

Between 2017 and 2019, high quality photos and videos of migrating humpback whales were taken by drones to determine their overall body condition, measuring their bodies in many different ways. Figuring out their sex, body length, volume and mass, they were able to calculate and “estimate the energetic cost of the entire migration and time on the breeding ground” (Bernier-Graveline 2.4), including the amount of converted energy from krill they eat.

Overall, adult whales seemed to be in peak condition over the months of March and May, and in lowest condition across August and December. They have been seen within the feeding grounds for about 175 days to eat enough to then have enough energy for the next 190 days of travel and fasting. These data points have slowly shifted around, whether it be the date that they leave and arrive at their destinations or when they begin to bulk up for the trip. This proves that their ecosystem is constantly changing, and more so with the effects of climate change on the rise. Warmer temperatures and less prey to go around may pose a huge issue for these humpback populations, since they rely on extensive krill populations to stock up on energy. Further temperature change could lead to devastating effects to the entire ecosystem, which needs intervention to attempt to prevent. The Convention for the Conservation of Antarctic Marine Living Resources is making that effort to protect krill populations which will allow for foraging success for humpback whales and to help promote the birth of their many future generations to come.

For more information, check out the original scientific paper:

Bernier-Graveline, A., Nash, S.B., Bierlich, K.C., Friedlaender, A., Johnston, D.W., Castrillon, J., Botero-Acosta, N., Caballero, S., & Christiansen, F. (2025). Drone-based photogrammetry provides estimates of the energetic cost of migration for humpback whales between Antarctica and Colombia. Marine Mammal Science, 41:e70048. https://doi.org/10.1111/mms.70048

Researchers documenting whale behavior off the south coast of Iceland have reported rare and surprising interactions between killer whales (Orcinus orca) and newborn long-finned pilot whales (Globicephala melas). In two encounters that took place on June 23, 2022, and June 20, 2023, scientists observed groups of killer whales in close proximity to neonate pilot whales. These sightings have raised new questions about interspecies behavior in the North Atlantic.

In each sighting, the newborn pilot whales were swimming close to several killer whales. What made this unusual was that no adult pilot whales were seen nearby, which is concerning because newborn calves are weak swimmers and depend fully on their mothers for protection and support.

The killer whales in these encounters did not show any signs of aggression. They were moving slowly and calmly, and some even swam beside the calves. Researchers were surprised by this because killer whales in this area mostly eat fish, not marine mammals. The calm behavior suggested that the killer whales might not have been trying to hunt, but it was still unclear why they were approaching the calves at all.

Since the scientists did not see the entire interaction from beginning to end, they could not say for sure what the killer whales were doing. They shared several possible ideas. One possibility is that the killer whales were simply being curious. Another is that they were practicing certain skills or even acting in a social or playful way. It is also possible that the calves had become separated from their groups before the killer whales arrived.

The researchers used photographs and observations from both land and boats to identify individual killer whales and track what was happening. Even though only two encounters were recorded, the events stood out because this type of behavior has not been documented often in Icelandic waters.

These sightings matter because they show how little we still know about the relationships between different whale species. Changes in ocean conditions, food availability, or human activity could all play a part in shaping how these animals behave. When something unusual happens in the ocean, it can be an early sign that bigger environmental changes are taking place.

Understanding how killer whales and pilot whales interact helps scientists learn more about the health of marine ecosystems. As the ocean continues to change, paying attention to rare events like this can help guide conservation efforts and protect marine life in Iceland and beyond.

For more information, check out the original scientific paper:

Baumgartner, C. D., Selbmann, A., Middel, H., Schulze, J., Bellon, G., & Samarra, F. I. (2025). Interactions between killer whales (Orcinus orca) and neonate long‐finned pilot whales (Globicephala melas) off South Iceland. Ecology and Evolution, 15(4), e71193. https://doi.org/10.1002/ece3.71193

Oil spills have a major negative impact on the ocean and all the animals and critters that live in it. Fur seals belong to a group of pinnipeds, which include seals, walruses, and sea lions. Out of all the pinnipeds, oil spills are specifically dangerous to the fur seal, because they need their thick fur coat to keep them warm. When they are slicked in oil, their fur is not able to function in such a way. When a fur seal is oiled, it has a harder time swimming and finding food. As a fur seal pup, it is a great challenge to try to escape areas that threaten their health. Fur seals need our help when facing an oil spill.

Oil spills are most commonly caused by shipping vessels, which frequently float through Banks Peninsula, New Zealand. Scientists work to understand where fur seals are located and how many of them are around. Understanding where large groups of seals are helps responders guide them away from oil spills. Counting the seals is hard because they move and look alike. So, they mark some pups, counting how many return and how many unmarked come to the area.

Scientists in New Zealand found 41 seal colonies, or groups that have babies together. 25 groups were completely new, and there were roughly 3,700 baby fur seals in the area this year. This information is applied to plan a response to help baby fur seals when oil enters their waters. Because there is a greater amount of pups, there are more to save, and not much time to do it in.

The two most proactive ways to help them is to divert them from the area where there is oil, and prevent oil from reaching them. Responders have been working to deter them and find new ways to stop the spread of oil in the oceans. It is challenging to block oil from reaching groups in Banks Peninsula because of how fast waves of water move through. However, current efforts to encourage fur seals to move away from an oil spill is to approach them with boats to scare them off or make loud noises.

After many efforts to prevent oil spills from happening in the ocean, scientists recognize that this issue is going to continue, and it is important to find ways that we can help save fur seals from such a great threat to their lives. Efforts can be tweaked and used in other areas as well, and such efforts to help fur seals sets a foundation for future work to flourish in helping marine mammals in harmful events.

For more information, check out the original scientific paper:

Hall, A.A., Chilvers, B.L., & Weir, J.S. (2025). Planning for a pinniped response during a marine oil spill. Environmental Science and Pollution Research, 32, 10929-10944. https://doi.org/10.1007/s11356-025-36192-y

Imagine you are a scientist, and you’ve been tasked with sorting different whale species into just 2 groups. How would you do it? Would you categorize them as loud vs quiet species? Transient vs resident species? Cute vs kinda weird-looking?

Some scientists have floated around the fight-or-flight species theory. The theory suggests that different whale species belong to 1 of 2 categories in terms of antipredator strategy. Either a species stands its ground and fights the predator (fight species), or it runs for its life (flight species). This antipredator strategy should then determine other behavioral patterns between members of the same group. For example, because blue whales and fin whales flee in the presence of killer whales, which are known predators of other whale species, they should share some behavioral patterns.

Trevor A. Branch, a researcher at the University of Washington, set out to test whether the detectability of whale calls to predatory killer whales corresponded to whether the whales were fight-or-flight species. His research analyzed 83 populations of 15 species of whales, focusing on call frequencies. What he found was that flight whales would typically call out to each other at frequencies lower than 100Hz – too low for killer whales to detect. On the other hand, fight species would produce detectable calls exceeding 1500Hz despite being able to make calls beneath 100Hz. The paper supports the fight-or-flight species theory, with flight species exhibiting a behavioral pattern that produces calls beneath predator detection, a phenomenon
called acoustic crypsis. What this means is that the presence of killer whales might have shaped the behavior of flight species, leading them to choose acoustic crypsis However, Branch notes that other hypotheses could explain why these whale species use low-frequency calls. For example, one reason is that low frequencies travel further and give a greater opportunity to attract mates.

Though whale call frequency behaviors seem to be shared among whale species within the same fight-or-flight group, there is still plenty of research to be done.

For more information, check out the original scientific paper:

Branch, T.A. (2025) Most “flight” baleen whale species are acoustically cryptic to killer whales, unlike “fight” species. Marine Mammal Science, 41: e13228. https://doi.org/10.1111/mms.13228

Some of the harbor porpoises in the Baltic Sea have gone their entire lives never knowing what a bottlenose dolphin is or what it sounds like. However, when a single male named Yoda showed up in 2019, an interesting phenomenon occurred. When Yoda was active, the porpoises became undetectable. But when Yoda moved away to a different location, the porpoises showed themselves again. This behavior tells scientists a story about how these two species interact with each other without ever coming face to face.

Harbor porpoises are one of the most common marine mammals around the Northern Hemisphere’s oceans. They are small, toothed whales that have a handful of predators including orcas and sharks. In some oceans, they are killed for sport by bottlenose dolphins, so the porpoises have learned that avoiding the dolphins means they get to live another day.

In Denmark, citizens can use an app to log when they observe harbor porpoise activity. This citizen science approach combined with a more precise measuring device called an F-POD were used over a two-month period to understand the behavior of the local harbor porpoises when a single male bottlenose dolphin set up camp in their usual territory. F-PODs are a microphone-like device that hang within the water column and left for a period of time to collect data on sounds like dolphin or porpoise clicks. When the F-PODs caught the clicks of Yoda, they did not hear any from the porpoises. But when they did hear from the porpoises, there were no clicks from Yoda caught. This indicated that the porpoises intentionally left or became quiet when the dolphin was present and active. It’s still unknown whether the porpoises simply learned to become silent when Yoda was around or if they left the area entirely.

The observation of harbor porpoises avoiding a predator they had never encountered before supports what scientists have known about many whale species – that they learn from one another not just in the present but through generations. A mother teaches her daughter to stay silent when a predator is near, and that daughter in turn teaches her daughter the same even if she has never encountered that predator before. This creates a landscape of fear, or the shaping of behavior within a population based on the absence or presence of a predator whether or not that predator is present. Yoda and his impact on the porpoises in the Baltic Sea are just one example of the complex relationships that form within nature and create unique characteristics within a population or an entire species.

For more information, check out the original scientific paper:

Filatova, O.A., Fedutin, I.D., Jakobsen, F., Kindt-Larsen, L., & Wahlberg, M. (2025) Harbor porpoise displacement by a solitary bottlenose dolphin in the Baltic Sea. Marine Mammal Science, 41:e13164. https://doi.org/10.1111/mms.13164

Marine science has developed quite a bit over time as well as how we utilize the information we collect. As a community, scientists have started to use data collected in the past to analyze and apply that data to their studies.

One way scientists have collected and utilized data has been to track population sizes of various species. Collecting data on populations can be used in different ways, but one way it can come in extremely handy is for species conservation. While finding population numbers may only alert us that something needs to be done,  it can be used to our advantage as well.

Strandings, or live animals beached under unusual circumstances, have become an increasing issue. Scientists have found that they can use their data sets over long periods of time to track where, when, and what species it is affecting the most. Using these tools is extremely important to find what species need to be protected because if we don’t utilize these datasets, our marine populations could rapidly decrease to the point of extinction.

One group of scientists led by Rachel Lennon used data sets tracking cetaceans, a group including whales and dolphins, off the coasts of Scotland from 1992-2022. The scientists’ data specifically tracked the number of stranded cetaceans in the waters over this time span. The group then split the cetaceans into 5 distinct groups: Baleen Whales, Common Dolphins, Deep Divers, Pelagic Dolphins, and Harbor Porpoises in order to see what species were stranding the most and where it was happening. The team took the data, and graphed the annual number of strandings. While the 5 groups all showed increasing strandings each year, the graphs also proved that Common Dolphins and Baleen Whales had stranding rates that were increasing every year at an alarming rate, alerting them as to these species being the ones that needed to be prioritized in their effort to restore habitats and populations.

The team was also able to use spatiotemporal data which tracks where and when these strandings are occurring. This helped them to understand what could possibly be causing the issues as each group was stranding more in various coastal areas, not just equally spread out over the whole coast. This data helped them take the prioritized information they gathered and combine it with the spatiotemporal data to help draft the beginnings of a plan to help reduce the stranding issue we face today. Stranding has become an ever increasing issue highlighting the population decline of cetaceans in our waters. Data has become ever useful in the struggle to reduce strandings in the hopes we can stop these beloved animals from going extinct.

For more information, check out the original scientific paper:

Lennon, R. L., Williams, R. S., Allan, K. J., ten Doeschate, M. T. I., Davison, N. J., Babayan, S. A., & Brownlow, A. C. (2025) An approach to using stranding data to monitor cetacean population trends and guide conservation strategies. Scientific Reports, 15:28417.

Humpback whales, specifically those native to the Southern hemisphere, migrate seasonally from Antarctica to Colombia. This long journey is incredibly taxing on their bodies, as they do not eat much along the way. Consequently, they must rely on their thick blubber layers as their energy source, which is fueled by Antarctic krill. Until now, scientists have not had an accurate way to measure how much this migration energetically costs them.

Ph.D student Alexandre Bernier-Graveline and his colleagues set out to answer that question with the use of camera-equipped drones. These drones are flown over the migrating whales in Antarctica and Colombia, giving the team high-quality pictures of the individual whales, allowing them to measure their body length and width. This is a non-invasive method to collect data on the whales’ body conditions without disrupting their journey or behaviors.

The results of this study reveal an impressive toll taken on their bodies, both physically and energetically. Whales that have migrated to Colombia are much thinner than those that remain in the feeding grounds. By using body models of the measurements taken by the drones, the scientists are able to calculate the amount of body fat lost and estimate the amount of energy used on their voyage. Since the target group is reproductively viable and active, it was found that females that have recently given birth require higher energy amounts to complete the migration while feeding their calves.

Bernier-Graveline’s research is critical to understanding the biology and conservation of humpback whales in the region. These whales depend on Antarctic krill as their primary food source to build up high amounts of fat throughout the winter months. These Antarctic krill rely on sea ice for food and habitat, so declines in ice cover can reduce the krill abundance significantly. Any changes to the Antarctic ecosystem could deplete their food sources, which, in turn, depletes their energy supply to be able to complete their migration due to decreased fat reserves. Synthesizing data collected from these drones allows for researchers to establish a baseline for these migratory whales’ body composition. This baseline allowed for more accurate monitoring of how climate change impacts their populations, and what management strategies can be implemented to help conserve their abundance.

The use of these drones is advantageous to the marine mammal science community. It allows the tracking of health, population size, and the ecosystem changes in a safer and more accurate manner, while being more efficient than ever. As the oceans continue to warm, this method will be the front-runner in detecting warning signs from indicator species, allowing for better protection of species traveling these waters.

For more information, check out the original scientific paper:

Bernier-Graveline, A., Nash, S.B., Bierlich, K.C., Friedlaender, A., Johnston, D.W., Castrillon, J., Botero-Acosta, N., Caballero, S., & Christiansen, F. (2025). Drone-based photogrammetry provides estimates of the energetic cost of migration for humpback whales between Antarctica and Colombia. Marine Mammal Science, 41:e70048. https://doi.org/10.1111/mms.70048

A recent study in Science Advances reveals that the 2013 die-off of ochre sea stars along California’s coast triggered an unexpected gain for sea otters. The sea star, Pisaster ochraceus, is a keystone predator in rocky intertidal zones, primarily balancing the mussel population. When a widespread disease decimated these sea stars, mussels flourished. Researchers observed that mussel cover more than tripled resulting in growth of shells, as well as the expansion of mussels downward into tidal areas where sea otters could reach them.

The study notes, “In the absence of Pisaster, mussels increased in cover and expanded lower within the intertidal zone, enhancing their availability to foraging sea otters and serving as a prey surplus”. By 2016, sea otters were taking advantage of this new resource. Mussels became a significant part of their diet, helping boost energy intake and contributing to a population increase from roughly 373 to 535 animals over the following decade.

Researchers call this phenomenon “keystone interdependence.” As the paper explains, the collapse of one keystone predator in one ecosystem “can provide a surplus that supports another keystone predator in an adjacent system”. This demonstrates how changes in one ecosystem can ripple across neighboring habitats, linking food webs in unexpected ways.

The study also highlights the role of other prey. Sea otters did not only eat mussels. Outbreaks of sea urchins in nearby kelp forests provided additional food during the same period. However the paper reports, “By 2016, increased density of mussels, combined with fluctuations in the density of suitable urchin prey patches, resulted in an increase in foraging effort allocated to mussels as well as urchins”. This mix of food sources helped sea otters sustain higher energy intake than would have been possible otherwise.

Long-term impacts will depend on whether sea stars recover. If Pisaster populations rebound, mussels may shrink back to pre-2013 levels and sea otters may have to adjust their diets once again. For now, the collapse of Pisaster has created a rare ecological windfall for one of the Pacific Coast’s most iconic marine mammals.

This displays that predator-prey relationships can ripple across ecosystems in surprising ways. It highlights how the loss of one species can benefit another and reveals the complex, interconnected nature of coastal ecosystems.

For more information, check out the original scientific paper:

Smith, J.G., Fujii, J.A., Gaddam, R., Konrad, L., Lyon, S., Nicholson, T.E., Raimondi, P.T., Ridlon, A.D., Staedler, M., Tomoleoni, J.A., Yee, J.L., & Tinker, M.T. (2025). Keystone interdependence: Sea otter responses to a prey surplus following the collapse of a rocky intertidal predator. Science Advances, 11:1028. https://doi.org/10.1126/sciadv.adu1028

Many marine mammals, including Atlantic bottlenose dolphins, use different vocalizations: clicks, whistles, and other sounds, as a part of their daily life. These sounds are used for both communication and foraging, finding and obtaining food, making these vocalizations an important factor to their survival.

In a study published in the journal, Marine Mammal Science, scientists found that there was a significant decrease in the production of clicks, whistles, and other sounds when dolphins emit a bubble burst, a large, globular bubble released from their blowhole. This is different from the bubble stream, a train of smaller bubbles, which is known to be related to whistle production in dolphins. In this study, scientists used a hydrophone, an underwater microphone, to record individual dolphin vocalizations both before and during a bubble burst. They found that over 80% of two sounds, burst-pulses and whistles, were reduced during the bubble burst compared to the two seconds before. While clicks, which are used for echolocation, were heard more often, there was still a significant reduction in their production during the bubble burst.

Scientists found that the production of bubble bursts decreased the ability for a dolphin to vocalize. They believe this is due to the release of air when emitting a bubble burst reducing the pressure needed to make certain sounds. This raises the question as to why dolphins produce the bubble burst in the first place. It is thought that the bubble burst might have a similar communicative function as the bubble stream, alerting and relaying information to other dolphins. However, it is not clear if there is any other advantage to dolphins producing a bubble burst. It is also not entirely known why dolphins choose to release air at all when their air can be recycled and used to vocalize. This indicates that there must be some advantage to releasing air supply as opposed to recycling it. This is especially the case for the bubble burst that not only expels a large amount of air but also reduces vocalizations, even if for a short period of time.

This led to the scientists of the study calling for further research on the production of bubble bursts in dolphins. They want a better understanding of the reason dolphins release these large quantities of air, their purpose, and how they impact a dolphin’s survival. The production of the bubble burst takes away the primary method dolphins use, sound, to move and understand the world around them, putting them at a potential disadvantage. This makes further research necessary in understanding why dolphins exhibit a behavior that is not obviously advantageous.

The importance of understanding why marine mammals exhibit certain behaviors is essential to not only understanding individual species but also interactions within an ecosystem. This provides a better understanding of the world around us and allows people to be able to better protect these essential environments.

For more information, check out the original scientific paper:

Miller, E.C., Royse, C.D., Harris, C.R., & Johnson, C.M. (2025). Evidence for a decrease in vocalizations during bubble burst production in Atlantic bottlenose dolphins (Tursiops truncatus). Marine Mammal Science, 41:e70049. https://doi.org/10.1111/mms.70049

One of the more unknown side-effects of climate change is the increase in abundance and severity of diseases. Lots of factors contribute to this, but a big one is disease carriers being able to increase their range outside of what it was before. One of the victims of this rapid spread of disease is the Southern elephant seal, the largest seal species on the planet.

In 2023 the Patagonian colony of the southern elephant seals on Peninsula Valdes, Argentina were ravaged by a strain of the bird flu. This epidemic led to the death of nearly all newborn pups and an unknown amount of adults within the colony. This event was so particularly devastating because the outbreak began during breeding season, when most female seals are on shore in a small area.

To fully grasp the impact of this outbreak, scientists from Argentina and California worked together to model five different scenarios with five different outcomes for the colony. The first scenario was no death among adults or pups and the population continues growing at its rate before the epidemic. The second scenario assumes 100% pup death but no other factors. Scenario three included a 50% adult death on top of the 100% pup death from before. Scenario four continued with 100% pup death and 50% adult death but included no pup births in 2023. Scenario five takes this a step further, 100% pup death, 50% adult death and tests an additional death rate of 20% for adults in 2024 along with no pup births for both 2023 and 2024.

Campagna et al. determined that if newborn pups are the only deaths then the population will recover quickly due to a naturally high death rate in pups from age one to four. However, if the virus killed off a significant amount of female elephant seals then there would be immediate consequences. Assuming the seals are able to recover to their birth rate the population will recover. However, issues like resource limitations and other climate change factors could drastically lower these odds.

In the end, the actual results of the 2024 mating season suggests that there was a significant loss of adult elephant seals. If one outbreak can cause such a large die-off event there is no telling what will happen to other marine mammals as these outbreaks become more common.

For more information, check out the original scientific paper:

Campagna, C., Condit, R., Ferrari, M., Campagna, J., Eder, E., Uhart, M., Vanstreels, R.E.T., Falabella, V., Lewis, M.N. (2025). Predicting population consequences of an epidemic of High Pathogenicity Avian Influenza on Southern Elephant Seals. Marine Mammal Science, 41:e70009. https://doi.org/10.1111/mms.70009

For decades, the southern elephant seals of Península Valdés stood as a conservation success story. After commercial hunting stopped, they slowly rebuilt their numbers, returning each year to mate, give birth, and raise their young. By 2022, nearly 18,000 breeding females hauled out on the coast, a remarkable comeback for a species once pushed toward collapse.

Then, everything changed almost overnight.

In 2023, a fast-moving virus arrived with migratory birds: Highly Pathogenic Avian Influenza, better known as H5N1. This strain has devastated seabird populations worldwide and has increasingly crossed into mammals. By the time it reached Argentina’s coast, it was already known to infect sea lions, seals, and other wildlife.

What unfolded at Península Valdés was unlike anything scientists had documented before.

Newborn elephant seals began dying and then kept dying until almost none were left.

Beaches that should have been filled with the barks and squawks of thousands of pups instead fell chillingly silent. Their bodies were found packed along the shoreline, a sobering sight for researchers who had watched this colony thrive for years. Adult females also succumbed to the virus, although the exact number remains unknown; tides and scavengers quickly erased much of the evidence.

A recent study published in Marine Mammal Science reveals just how severe the long-term consequences could be. Using more than twenty years of population data, scientists modeled five different outbreak scenarios, ranging from the loss of pups alone to the combined deaths of pups and breeding females.

The results are sobering.

Losing an entire generation of pups is devastating, but on its own, it does not permanently alter population trends. Elephant seal pups naturally face steep odds in their first year of life. The real danger lies with adult female mortality. Each female lost represents not only a life cut short, but many future pups that will never be born.

In scenarios where adult female deaths were high, populations declined rapidly and took decades to recover if they recovered at all. Even under the most optimistic models, the number of breeding females in 2024 and 2025 is expected to drop sharply, wiping away years of slow population growth in a single blow. A species once viewed as stable has now been pushed back into uncertainty.

H5N1 continues to spread across South America and has even reached Antarctica, raising fears of repeat outbreaks in other seal colonies. Combined with climate change and shifting prey conditions, the virus may become a recurring threat lurking just offshore. The fate of the Península Valdés elephant seals now hangs in a fragile balance a reminder that even conservation success stories can be undone by a microscopic invader.

What Is H5N1? (Quick Facts)
• A strain of avian influenza that primarily infects birds
• “Highly pathogenic” means it spreads easily and causes severe disease
• Has increasingly jumped into mammals, including seals, sea lions, foxes, and, rarely, humans
• Crowded wildlife colonies allow rapid transmission and mass mortality
• Considered a growing global wildlife health threat

For more information, check out the original scientific paper:

Campagna, C., Condit, R., Ferrari, M., Campagna, J., Eder, E., Uhart, M., Vanstreels, R.E.T., Falabella, V., Lewis, M.N. (2025). Predicting population consequences of an epidemic of High Pathogenicity Avian Influenza on Southern Elephant Seals. Marine Mammal Science, 41:e70009. https://doi.org/10.1111/mms.70009

Killer whales are active predators of baleen whale species, which are a group of whales that filter feed using comb-like plates to scoop up shrimp, krill, or small fish. The killer whale will attack both mother and calf, and scientists have formed theories to explain how the lingering threat of killer whales may alter the behavior and ecology of such species, one of which is the “fight or flight” hypothesis. The theory states that baleen whale species can be divided into two groups: the “fight club” and the “flight club”. The “fight club” defends themselves and their calves by fighting back against the orca’s advance, and are typically larger, slow-moving, more maneuverable, and migrate closer to the shore to allow for easier defense when attacked. The “flight club”, however, flee the scene with their calves when attacked, and are usually slender in size, quick, and will migrate in open waters so that in the event of an attack, they may escape in any direction.

While these “clubs” have already adapted to surviving killer whale advances, one avenue has been left largely unexplored: are the calls used by baleen whales, mainly to find a mate, another form of defense?

The answer to this question is yes. The “flight club” will sing at frequencies below what the average killer whale can tune into, and use this to their advantage. Whale call frequencies are like the tone of our voices; sometimes they may sing at low frequencies or at high frequencies, in the same we can talk in a low or high voice. Since “flight” species naturally wish to evade the large predator, most have adapted to communicate at low frequencies that killer whales cannot hear, and therefore can communicate loudly across open water to find a mate without risking detection.

Five out of the six “fight club” species call at frequencies that are easily heard by killer whales, and will do so at loud frequencies that are heard from over 10 kilometers away. The exception was the gray whale, which will call at softer frequencies. This is likely due to the need to avoid killer whales during their long migration northward, which is a time when their calves are especially vulnerable.

The evidence presented in this paper, gathered from a literature review of baleen whale song frequency studies, supports the “fight or flight” hypothesis. The use of acoustic crypsis, or  being undetectable by sound (like how a dog whistle can be heard by dogs, but not humans), is beneficial to the “flight” species in defending themselves and their young against predatory advances by killer whales.

This hypothesis could have larger implications in the evolution of all baleen whales mating calls. “Flight” species call at low frequencies to find a mate and avoid detection, and since no one wants to be interrupted by a predator when mating, low frequency calls that are acoustically cryptic could prove to be attractive to females. Over time, their offspring will inherit lower call frequencies and preferences for low calls, continuing the cycle of calling at lower and lower frequencies. In “fight” species, females generally prefer long, complex songs that change over time, and because they can call at higher frequencies over broad ranges, their frequencies may trend higher with time and become more complex.

For more information, check out the original scientific paper:

Branch, T.A. (2025) Most “flight” baleen whale species are acoustically cryptic to killer whales, unlike “fight” species. Marine Mammal Science, 41: e13228. https://doi.org/10.1111/mms.13228

Dolphins are well-known to echolocate and communicate with each other through their vocalizations underwater. However, what may come as a surprise is the fact that dolphins can modify their communication and foraging efforts, in some circumstances, with the bubbles released from their blowhole. These bubbles may project information not just visually, but acoustically as well, since they are actually reflective of sound waves.

Past research has found a pattern of vocalizations co-occurring with one specific type of bubble production, the bubble stream — a series of small, consecutively-produced bubbles — thought to enhance and help clarify communication between dolphins. In contrast, scientists researching Atlantic bottlenose dolphins have recently discovered that a different type of bubble production is associated with a momentary lull in vocalizations, the bubble burst — a single, large, round mass of expelled air. To test this observed pattern, they recorded 11 dolphins across two studies and compared the amplitude — the intensity of the sound — recorded during the moment of each bubble burst to the 2 seconds preceding it. In each study the moment of the bubble burst was recorded as being multiple decibels quieter on average than the 2 seconds prior.

Dolphin vocalization, as currently understood, is powered by the controlled release of pressure from their nasal cavities Because of this, it is perhaps unsurprising that the abrupt release of pressure necessary to produce a bubble burst would fail to produce much sound. But the results of the study by Miller et al. still leaves a significant question unanswered: why do dolphins actually produce bubble bursts in different situations?

The lack of such a resolution may be disappointing to some, but it highlights a blindspot in our understanding of marine mammal ecology and an opportunity to fill that gap with further research, observations, and analyses. As familiar as these creatures may seem, they still manage to elude us, but with these findings we at least have an idea of where to go searching next.

For more information, check out the original scientific paper:

Miller, E.C., Royse, C.D., Harris, C.R., & Johnson, C.M. (2025). Evidence for a decrease in vocalizations during bubble burst production in Atlantic bottlenose dolphins (Tursiops truncatus). Marine Mammal Science, 41:e70049. https://doi.org/10.1111/mms.70049

A migrating humpback whale can consume and use 56,000 kilograms of krill, or the equivalent of 11,000 kilograms of blubber, for a yearly migration from Antarctica to Columbia. The productive waters of the Antarctic are a bingeing fest for these animals, a preemptive measure for the long swim to the breeding grounds off the coast of Columbia.

Rapid environmental changes in the Western Antarctic Peninsula, a crucial habitat for krill, affect krill abundance and the ability of these migrating whales to prepare for their journey. The changes in the Antarctic include “consecutive record-breaking lows in sea ice extent” since 2016. Antarctic sea ice is crucial for krill population dynamics, providing shelter from predation and a place for larvae to develop. The decline in sea ice could be an indicator of the suitability for krill spawning, with an expected shrink of 51% by the end of the century. With a significantly smaller population of krill in Antarctica, humpback whales will have less of a chance to build sufficient fat stores for the long migration ahead.

As a way to estimate the energetic cost of this specific migration, the International Whaling Commission funded a study using drone-based photogrammetry to take high-resolution photos or videos of a stock of whales from 2017 to 2019. These photos and videos were analyzed by scientists, cataloging individual whales’ body sizes, volumes, mass, and overall condition. This data was then used in a model to predict the total change in body mass over the course of the migration, helping to further understand the energetic demand of the trip.

It was found that the changing of the Antarctic ecosystem has a bottom-up effect on the food chain: changing the abundance of krill and consequently affecting humpback whales’ eating before the migration. The entire ecosystem feels this upward cascading effect induced by low krill quantities, with humpback whales’ body condition being a primary concern should these predicted trends continue. There is currently an effort by the Commission for the Conservation of Marine Living Resources to develop a plan to help preserve this ecosystem and allow the humpback whales to be well-fed for their long trip.

With the use of drones, the migration cost of humpback whales is better understood than ever before. With this understanding comes the responsibility of protecting this system, including helping to sustain krill populations for the whales by confronting the changing sea ice issues. Krill is a critical energy source for the whales, and the lack of sea ice in the Antarctic is impacting the population more and more every year, with each migration becoming increasingly difficult as humpback whales’ favorite snack disappears.

For more information, check out the original scientific paper:

Bernier-Graveline, A., Nash, S.B., Bierlich, K.C., Friedlaender, A., Johnston, D.W., Castrillon, J., Botero-Acosta, N., Caballero, S., & Christiansen, F. (2025). Drone-based photogrammetry provides estimates of the energetic cost of migration for humpback whales between Antarctica and Colombia. Marine Mammal Science, 41:e70048. https://doi.org/10.1111/mms.70048

There is good news and bad news from the coast of New Zealand. A new study shows that the local fur seal population is growing, a huge win after years of being overhunted. The bad news? They are living in the middle of a dangerous shipping highway, putting them directly in harm’s way from oil spills, a threat history shows we cannot ignore.

Past disasters from around the world, like the Exxon Valdez spill, have proven how devastating oil can be to marine life. This new research warns that a similar accident in New Zealand’s busy shopping lanes would be catastrophic for the seals.

Researchers counted seals around the Banks Peninsula for the first time in decades, finding way more than expected, between 13,147 and 17,675 animals, with babies being born at 41 different spots around the coast.

Unfortunately this area is a major risk zone for oil spills. It has a huge cargo port and is a favorite spot for large cruise ships, with more ships meaning a higher chance of an accident.

Fur seals are especially in danger from oil. Their survival depends on their thick, two layered coats. The outer layer keeps them dry, while the dense undercoat traps air to keep them warm. This is why the oil is so deadly. It glues the fur together, destroying its waterproofing and insulation. A seal will quickly become soaked, freezing, and poisoned as it tries to clean itself. This is also why rescue is so difficult. Cleaning the sticky oil from their fur is a slow, stressful process for the animal, and even successful washes often fail to restore the fur’s true properties.

Because of this, the scientists say the best way to help these seals is to stop them from getting oily in the first place. But the location of where these seals live is another challenge. The rough and rocky coastline makes it tough to use normal oil spill tools like floating barriers.

So, what can be done? The researchers have suggested a couple of creative ideas. They could use underwater noise machines or other safe tools to scare seals away from oil slicks. Also, for small groups of seal pups, teams might be able to carefully relocate them for a short period of time while the oil is cleaned up.

The big takeaway is that as seal numbers grow, we need to have a plan of action to keep them safe from any potential accidents. Scientists say we need to keep a close eye on their increasing numbers and test these new protection methods before a spill ever happens.

For more information, check out the original scientific paper:

Hall, A.A., Chilvers, B.L., & Weir, J.S. (2025). Planning for a pinniped response during a marine oil spill. Environmental Science and Pollution Research, 32, 10929-10944. https://doi.org/10.1007/s11356-025-36192-y

Bottlenose dolphins, best known for their toothy smiles and playful water acrobatics, are earning themselves quite the “bully” reputation in the Baltic Sea, according to researcher Olga A. Filatova. A study published in the Marine Mammal Science journal covers the extent to which porpoises – small, stout, charismatic marine mammals – are being displaced from their homes and foraging grounds near the island of Funen, Denmark, due to fear of aggressive dolphins.

Historically, dolphins have been viewed as the mascot for fun. Boasting goofy smiles and playful temperaments, many tourists seek out dolphin experiences as a fun family excursion on vacation. While dolphins generally prove harmless to humans, the same can’t be said for Harbor Porpoises in the Baltic Sea, who have seen the darker side of their evolutionarily distant cousins.

Dolphins and porpoises share some lineage, both members of the odontocete family, or “toothed whales.” Dolphins are not true predators of porpoises as they do not eat them; but these marine mammals do have some nutritional overlap, primarily feeding on fish, crustaceans, and squid. Dietary similarities have led scientists to hypothesize about the potential for food competition leading to these violent encounters. However, related studies on the social strategies of dolphins have discovered that aggressive male dolphins are often the product of sexual frustration, rather than dietary competition. In previous, sporadic cases of violent interactions between dolphins and porpoises, aggressive behaviors have led porpoises to become stranded, often resulting in extensive injury and even death.

This study used acoustics as the primary detection method to determine the presence of porpoises and dolphins. Many odontocetes use “clicking” as a method of echolocation and communication, using vibrations in the water to help find prey. In the study, clicks were picked up by underwater detectors, referred to as F-PODS, which can differentiate between the high frequency clicks of porpoises, versus the low frequency clicks of dolphins (other sounds were also mentioned, but filtered out, such as boat motors). Results showed that in the presence of one singular dolphin, vocalization rates of harbor porpoises decreased or were nonexistent. This indicates that when the dolphin was nearby, porpoises were either completely silent, or were not present in the area at all, due to fear of aggression. This fear has altered the foraging patterns of harbor porpoises in this ecosystem.

Marine ecosystems, like the Baltic Sea system, are quite fragile, with predators having a great impact on the rest of the organisms in the community. By altering the trophic cascade, or food chain, prey populations can go unchecked, causing overpopulation, which generally has detrimental effects on the rest of the environment. Not only this, but the porpoises, the initial predators in this food chain, are left to find new foraging grounds, a task greatly challenged by human development.

Human development is the most likely cause of the dolphins encroaching on the porpoise grounds. Due to the increase in oceanic noise pollution, development of in-ocean fisheries, oil extraction, and other marine development, sensitive marine mammal populations are at risk of relocation, making their already challenging lives even more difficult.

For more information, check out the original scientific paper:

Filatova, O.A., Fedutin, I.D., Jakobsen, F., Kindt-Larsen, L., & Wahlberg, M. (2025) Harbor porpoise displacement by a solitary bottlenose dolphin in the Baltic Sea. Marine Mammal Science, 41:e13164. https://doi.org/10.1111/mms.13164

This study by Arias published in 2024 evaluates how whale watching vessels affects the behavior of Southern right whales (Eubalaena ausralis) in the Bahía San Antonio Marine Protected Area (BSAMPA), Argentina, and helps develop some ideas to more sustainably and safely continue whale watching. As whale watching becomes more popular, there are concerns that the vessels have begun affecting cetacean behaviors. Arias aims to help establish guidelines for the vessels based on behavioral data.

Between 2013-2023, researchers collected behavioral observations during both research trips (with minimal disturbance) as well as commercial whale watching trips. They classified behavior into five states: surface active, traveling, resting, social, and underwater. They were also grouped by social composition: solitary individuals (SIs), nonsurface active groups (NonSAGs), and surface-active groups (SAGs).

Comparisons between both control and impact conditions showed that the whale watching vessels significantly altered behavior in SIs and NonSAGs, but had no effect on SAGs. SIs and NonSAGs spent significantly less time resting and underwater and spent significantly more time engaged in surface active behaviors when exposed to these vessels. The issue lies in the fact that resting and underwater time are associated with energy conservation, and the vessels disrupted that, also causing the whales to take more time to return to the resting state. SIs and NonSAGs showed significant changes in surface active behavior, with changes at 17% and 21% of vessel exposure respectively. Resting and underwater states were affected at levels of 44-62%.

The actual vessel exposure in BSAMPA across all the years was well below these thresholds, around 4%. So, while short term behavioral changes were observed, they shouldn’t be considered biologically significant. The whale watching industry in BSAMPA is currently considered sustainable according to the study. The study, however, still shows and emphasizes why the practice needs to be actively managed in order to protect the whale population.

For more information, check out the original scientific paper:

Arias, M., Dans, S., Crespo, E.A., & González, R.A.C. (2025) Southern right whale behavioral changes due to interactions with whale-watching vessels: evidence-based calculations aimed at improving management policies. Marine Mammal Science, 41: e13149. https://doi.org/10.1111/mms.13149

Climate change is a worsening problem globally, as human-caused actions have negative consequences globally that appear in a myriad of ways. We are familiar with habitat destruction and temperature changes in the water and air, but a lesser known impact is the increased severity and spread of disease epidemics. In the wild, rapidly spreading disease is hard to track, and  associated death rates are typically hard to understand because they require population estimates to be accurate and up to date. Alternatively, mathematical models can be used to understand potential population outcomes based on what could be considered a mass death (mortality) event.

Scientists wanted to understand the effects of a mass mortality event in 2023 related to the spread of Mammalian bird flu in a population of Southern Elephant seals on Peninsula Valdez in Argentina. This was done using population estimates and statistical modelling. Five specific scenarios were modelled in the study; a baseline population progression under normal circumstances, a scenario in which 100% of pups died and adults remained healthy, 100% pup death and 50% adult death, 100% pup death and 50% adult death as well as failed reproduction the next year.  Finally they modelled 100% pup death, 50% adult death, failed reproduction and a second mortality event the next year in which 20% of adults died. The researchers ran the modelling projections and determined a year that the population might recover to pre-epidemic conditions. These projections were less favorable in situations with higher adult mortality, due to the lack of females having and supporting pups. Reproduction is key to population growth, and without a healthy adult female seal population, there are few individuals of age, requiring adults to become viable before the population can begin to recover. This can be seen in the modelling results, as when there is no adult mortality, the population takes only an estimated 10 years to recover when compared to scenario five with multiple waves of adult mortality that estimates nearly 100 years of growth to fully recover.

This study emphasizes the importance of understanding the nuanced impact of climate change so that future events like this can be anticipated and better responded to. Modelling is exceedingly useful for understanding complex population issues such as epidemics and how they will affect the species in the future, especially when they are often out to sea and hard to count. In this specific case, the reality was found to be close to that of scenarios three and four, indicating that this was a serious mortality event that had severe effects on the adult population, meaning the population will take somewhere between 70 and 80 years to recover barring future mortality events.

For more information, check out the original scientific paper:

Campagna, C., Condit, R., Ferrari, M., Campagna, J., Eder, E., Uhart, M., Vanstreels, R.E.T., Falabella, V., Lewis, M.N. (2025). Predicting population consequences of an epidemic of High Pathogenicity Avian Influenza on Southern Elephant Seals. Marine Mammal Science, 41:e70009. https://doi.org/10.1111/mms.70009

When you think of how dolphins behave, what comes to your mind? For many people, they probably imagine a smiling dolphin doing flips and tricks to the amazement of onlookers. We tend to think of dolphins in a positive light, focusing on their charisma and cuteness in addition to their intelligence. But there is a dark side to dolphins.

Harbor porpoises are small toothed whales that prefer cold water, such as in the northern Atlantic Ocean. These whales have a unique interaction with bottlenose dolphins: they hide in fear. Reports of “porpicide” or the targeted killing of porpoises have been observed in bottlenose dolphin pods, notably during the mating season. It is suspected that male bottlenose dolphins release aggression and sexual frustration by attacking harbor porpoises, often harassing the porpoise to a point of serious injury or death. These repeated aggressive encounters with bottlenose dolphins have caused many harbor porpoise pods to intentionally avoid areas where bottlenose dolphins are known to be active.

But, what if a pod of porpoises never encountered a bottlenose dolphin before? Harbor porpoises are the only native cetacean to the Baltic Sea, meaning it is unlikely their population ever encountered a bottlenose dolphin. That is, until a lone male bottlenose dolphin found his way into the Baltic Sea in 2016.

Researchers from the University of Denmark set out to examine how the harbor porpoises in the Baltic Sea reacted to the new threat. The team set out click detectors which would pick up the sounds of the harbor porpoises and the bottlenose dolphin as they moved through the area. The team also conducted surveys with locals in areas where the bottlenose dolphin had been spotted, asking them questions regarding harbor porpoise activity.

The researchers made a remarkable discovery: when clicks from the bottlenose dolphin were detected, the harbor porpoises in that area reduced their activity. In other words, the harbor porpoises hid from the dolphin. Somehow, these animals could sense the danger of the dolphin’s presence and actively avoided the area in which the dolphin was. The researchers described this phenomenon as a “landscape of fear,” which is typically seen in predator-prey dynamics. In the “landscape of fear,” the mere presence of a potential threat is enough to alter the behavior of prey, which in this case is the harbor porpoises.

While these findings are exciting, the researchers note that they are not entirely certain as to how the harbor porpoises know to avoid the bottlenose dolphin. One hypothesis they suggested was that the porpoises had an instinctive fear of dolphins, but they did not have concrete evidence of this claim. Another hypothesis was that the porpoises had survived previous aggressive encounters with dolphins and as a result learned to avoid dolphins, but there were no recorded sightings of dolphins in the area before the lone male was spotted. With these shortcomings, the researchers hope that their research can facilitate further studies into this unique interaction between harbor porpoises and dolphins.

For more information, check out the original scientific paper:

Filatova, O.A., Fedutin, I.D., Jakobsen, F., Kindt-Larsen, L., & Wahlberg, M. (2025) Harbor porpoise displacement by a solitary bottlenose dolphin in the Baltic Sea. Marine Mammal Science, 41:e13164. https://doi.org/10.1111/mms.13164

Huge whales such as humpbacks and gray whales journey thousands of miles from cold polar seas to warm tropical seas on a yearly basis. Many would reasonably assume that the purpose of these migrations is to find calmer, safer locations to give birth and raise their newborn calves. However, a recent study expressed that whales are doing something much more interesting along the way: transporting nutrients that help tropical waters thrive.

During the summer months in the Arctic, whales feed almost nonstop, consuming large portions of krill. Because polar waters are rich in food, whales are able to build up large energy reserves and then store them as blubber. This stored energy becomes crucial when winter begins, as whales leave these feeding grounds in favor of tropical waters, where they will often go months without eating. Even so, their ecological impact does not pause during these journeys. Whales actually continue to release nutrients into surrounding waters through the shedding of skin, excretion of urine, and depositing of placentas/carcasses. The nutrients released through these methods effectively function as fertilizer for the ocean. They enhance the growth of floating plants like phytoplankton, which in turn feeds zooplankton, smaller forager fish, larger predatory fish, and ultimately the top predators like sharks and marine mammals.

Building on the idea of whales as nutrient transporters, the new research discovered that migrating whales are able to move thousands of tons of nitrogen and carbon from polar regions to the tropics every year. This is a significant contribution today, but historically the levels were far greater when whale populations were closer to their pre-whaling abundance. Before commercial whaling significantly dropped whale populations, they delivered three times as much.

This decline matters because nutrient delivery makes a substantial difference in tropical waters. Despite being warm and clear, tropical waters are often nutrient-poor and rely on the limited natural sources of nitrogen. By bringing nitrogen southward, whales are helping stimulate the growth of plants in areas where productivity would otherwise be restricted. As an example, the nutrients transported by humpback whales during their breeding season has the potential to exceed the nutrients that are brought in by natural ocean mixing in Hawaii.

Taken together, these findings express that not only are whales amazing animals, they are also critical drivers of ecosystem health. Their migrations connect vastly differing parts of the ocean, supporting life far from where they actually feed. As whale populations continue to rebound from past hunting, the natural nutrient pipeline is being rebuilt alongside them. Protecting whales doesn’t simply save a species, it helps keep oceans healthy for the many lives that depend on them.

For more information, check out the original scientific paper:

Roman, J., Abraham, A.J., Kiszka, J.J., Costa, D.P., Doughty, C.E., Friedlaender, A., Hückstädt, L.A., Marcondes, M., Wetsel, E., Pershing, A.J. (2025). Migrating baleen whales transport high-latitude nutrients to tropical and subtropical ecosystems. Nature Communications, 16, 2125. https://doi.org/10.1002/ece3.71193

You know those really cute heads that pop out of the water, whose cuteness can only be compared to that of a puppy? Well, that’s the harbor seal! But they are so much more than just a cute face, because their poop is a powerful tool that can be used to observe the biodiversity of fish species in an ecosystem.

In 2020, on the Hvaler Islands in Norway, researchers from the University of Gotherberg collected 73 poop samples from harbor seals to analyze their diet. They can get an idea of what they are eating because ear bones from fish and beaks from octopus and squid will not be digested at all, and can be identified when taken out of the poop.

Through the collection of ear bones and beaks, researchers were able to measure the harbor seals’ diet quality, diet composition (exact species they were eating), and for some, the size of their prey (with just a simple measurement of their ear bones).

Now, researchers did not dig through harbor seal poop just to see what they were eating, but to see how/if their diets have changed and, if so, help determine why. Luckily for harbor seals, they are not picky eaters, and instead have a broad diet that changes based on what species are available to them, so what they are eating is reflective of the fish available in the ocean.

After comparing 2020 data to data from 1977-78 and 1989, researchers were able to determine that harbor seals’ diets have indeed changed. They went from having diets rich in herring and cod, both nutritionally dense, high-energy, and larger species, to diets dominated by sandeels and pout, which are smaller and less energetic. This new diet, which has been forced upon them due to decreasing fish populations and environmental changes, may not be nutritionally dense enough to fulfill their needs. This leads to stress within the harbor seal communities.

While this change in harbor seals diet could just be due to seasonal changes and short term changes in fish abundance, when researchers compared their findings to similar studies they found that this shift was not a short term change. Because this is a large shift it is likely due to long term changes in the environment. It’s also known that cod and herring fish populations have decreased over the last decade from fishing, and it’s shown in this diet shift.

Harbor seals’ change in diet is a sign of a bigger problem. Not only are harbor seals no longer able to consume as much really yummy prey, but the ocean and what’s living in it is changing. Overfishing and warming ocean temperatures lead to less fish, fish leaving areas where they are needed (by predators), and overall less nutritionally dense diets for sea creatures who rely on all types of fish.

When seals cannot eat the yummy food they want to eat, then humans likely cannot either. For example, cod, a major part of the harbor seals historical diet is also enjoyed by many humans across the world. So, humans will also have to turn to new fish species that may be less desirable if the ocean’s health is not restored.

For harbor seals to have the happy ending they deserve, which includes tummies full of high-energy food, research must continue to understand the implications of this diet shift and the environmental changes that are behind it. We need to help harbor seal populations be happy, healthy, and fat!

For more information, check out the original scientific paper:

Kappa, F., Härkönen, T., Freitas, C., Carroll, D., & Harding, K. C. (2025). Shifting harbor seal (Phoca vitulina) diet may reflect ecosystem changes in Skagerrak. Marine Mammal Science, 42: e70069. https://doi.org/10.1111/mms.70069

EUROPE- Killer whales are some of the most charismatic megafauna (large mammals that are popular with the public) we see in the oceans because we have whale watching, documentaries, and books about them. The problem mentioned in this study was the decline in North Atlantic killer whale populations. There are estimated to be around 15,000 North Atlantic killer whales in the wild as of 2025, which is a low population number for a species that used to be estimated to have tens of thousands. The North Atlantic killer whales in Europe are seeing declines in their populations due to restricted gene flow(Genes are not mixed with genes outside of their family). This lack of gene flow was found to be linked to the herring stock collapse. When the collapse started, killer whales were less likely to travel when they found a good food source. This causes a lack of gene diversity because killer whales don’t reproduce within their pods. They have to travel to a different pod to carry their genes along. This poses a significant problem for killer whales in Europe, as they are reluctant to travel to other countries if they have been unable to find their preferred prey source for an extended period. A study was conducted involving North Atlantic killer whales from Scotland, Norway, Iceland, and East Greenland. In this study, they wanted to see if the location of these killer whales is linked to their prey type and the prey’s distribution (where their prey is found). The major finding was, gene flow among herring-associated killer whales was mostly restricted over the past 2-3 generations, which corresponds with the recent herring stock collapse. There was a herring stock collapse that started in the late 1960s, and the ocean and industry have been feeling the effects for years. Nowadays, European oceans are starting to feel those same indications of the past collapse. As early as 2026, the herring could hit the BLIM (Biomass limit in ocean), with current overfishing, with no changes to laws.  The European herring population might not be able to recover this time and could be overfished to functional extinction.  Another factor affecting North Atlantic killer whales is the habitat and ecological fragmentation (broken up habitat) that is taking place, lowering their numbers by restricting males from leaving their pods to reproduce with nearby females. So this poses the question of whether we can get our herring and European North Atlantic killer whales back to a healthy population? This answer is complex and has numerous components. So the simple answer is yes, but the long-winded answer is that the fishing industries will have to change, and protections will have to be enforced more heavily. We can look at numbers and see if a mixed diet would bridge the gap that killer whales need, but will it be enough for them to survive?

For more information, check out the original scientific paper:

Baumgartner, C.D., Jourdain, E., Bonhoeffer, S., et al. (2025). Kinship clustering within an ecologically diverse killer whale metapopulation. Heredity, 134: 109-119.

There are a lot more to sea otters than their charismatic faces and snuggly behavior with one another! Their diet preferences vary due to learning how to open/eat an organism, location, etc. Some popular examples of food that otters consume are sea urchins, mussels, crabs, abalone, and oysters.

A study was conducted in Kachemak Bay Alaska, with the underlying question on how sea otters might disrupt oyster farming. To study this, scan surveys were used to compare sea otter behavior in farm controlled areas. The surveys scanned the water surface from one point and recorded the activity of each individual sea otter. Then, 6 categories were designed: Resting, grooming, interacting, swimming, hauled out, and also foraging.

A total of 35 scan surveys were conducted by farmed bays to assess sea otter behavior and habitat use. Contrary to initial expectations, the study found that sea otters did not preferentially use aquaculture farms for resting and foraging compared to control areas. Instead, scan survey results indicated equal or lower use of farm sites relative to non-farmed reference and control locations. Observations revealed consistently high foraging success, suggesting that prey availability and foraging efficiency did not differ. These findings indicate that aquaculture farms may not provide a significant foraging or resting advantage for sea otters and that otters are capable of maintaining high foraging success across a range of environmental conditions.

This study examined the sea otter activity around mariculture farms and areas with no farms to consider the interactions between sea otters and oyster farms. Surprisingly, NO farm oysters were observed to be consumed by sea otters. On a broader scale, this signifies how studies can show how marine mammals interact with aquaculture more than what initially meets the eye!

For more information, check out the original scientific paper:

Reynolds, E., Konar, B., Horstmann, L. (2025). Sea otter interactions with mariculture oyster farms. The Journal of Wildlife Management, 89:e70055. https://doi.org/10.1002/jwmg.70055

Humpback whales make one of nature’s most extreme round-trip journeys, and new research shows the toll it takes on their bodies and their food supply. On average, an adult loses the equivalent of about 11,000 kilograms of blubber during migration, burning through roughly 5,000 kilograms of fat to fuel the trip from Antarctic feeding grounds to tropical breeding areas and back. To rebuild those reserves, each whale must devour tens of tons of Antarctic krill—tiny shrimp-like crustaceans that cluster in dense swarms—over a short summer “feast” before the long winter “fast.”

Using drones, scientists measured whales’ body shape from above, then converted changes in their “plumpness” into estimates of blubber volume, mass, and energy use across the migration. The results show that adults can lose more than a third of their body-fat condition over the journey, underscoring just how dependent they are on rich Antarctic feeding grounds.

By translating fat loss into food requirements, the team estimated how much krill each whale must eat to replace those energy stores. This kind of energetic accounting links individual health directly to the availability of krill in key feeding areas along the Western Antarctic Peninsula.

Antarctic krill rely on sea ice, especially in winter, because ice-covered waters support the algae and shelter young krill need to survive. As sea ice extent and duration have declined in parts of the Antarctic due to warming, krill numbers have also dropped, shrinking the buffet available to whales.

At the same time, humpback whale populations are rebounding from commercial whaling, meaning more mouths competing for a potentially smaller krill pie. Research has already linked years of poor krill availability to fewer pregnancies in humpback whales, suggesting that food shortages can quickly slow population recovery.

The new energetic estimates give managers concrete numbers for how much krill recovering whale populations may need, season by season. That information is vital for the international body that regulates the Antarctic krill fishery, which aims to use an “ecosystem-based” approach —one that leaves enough krill in the water for whales, penguins, and seals while supporting a growing fishing industry.

Future rules will likely need to limit local krill catches in areas and times when whales gather to feed, especially as sea ice continues to shrink. For humpbacks, the study makes one thing clear: their recovery depends not just on protection from harpoons, but on safeguarding the icy, krill- rich seas that refill their blubber bank each year.

For more information, check out the original scientific paper:

Bernier-Graveline, A., Nash, S.B., Bierlich, K.C., Friedlaender, A., Johnston, D.W., Castrillon, J., Botero-Acosta, N., Caballero, S., & Christiansen, F. (2025). Drone-based photogrammetry provides estimates of the energetic cost of migration for humpback whales between Antarctica and Colombia. Marine Mammal Science, 41:e70048. https://doi.org/10.1111/mms.70048

Marine mammals, particularly the remarkably adaptable Cetaceans (such as dolphins, porpoises, and both Baleen and deep-diving whales), inhabit nearly every corner of the global ocean. However, increasing anthropogenic stressors are negatively affecting these populations, frequently leading to stranding events and mortality. This essay argues that stranding data offers a crucial conservation method, providing necessary insight into population dynamics and mortality causes that can directly inform research priorities and drive effective management strategies to reduce population decrease.

While human infrastructure keeps evolving, stressors become more common and harmful for these charismatic individuals. Some of the greatest contributors to strandings and stress inducing activities in the ocean are mostly acoustic related practices. This being said these are not at all the only drivers for cetacean strandings. But, what does this stranding data really tell us? How does this information help researchers? Well, with the use of what is known as Level A stranding data, scientists collect information on species, date, location, sex, and age of the individuals they find. Over time, and with the addition of new data, researchers are able to predict how individual species populations are doing depending on their stranding data. It is imperative that the data sets are taken over a large portion of time in order to provide complete information and avoid misleading datasets.

In a recent study titled An approach to using stranding data to monitor cetacean population trends and guide conservation strategies researchers implemented a preexisting data set that included over 30 years of information regarding strandings of Common Dolphin, Pelagic Dolphins, Harbor Porpoise, Baleen whales, and Deep diving whales (Sperm whales). The importance of the Level A data is its ability to build a baseline for population trends, like migration, population decrease, and population pressures. Allowing for appropriate conservation measures to be implemented depending on the data and results gathered.

For this specific article, researchers focused their attention on the Scottish coastal waters and the 5 individuals species. The data led them to understand conservation priorities between species depending on their stranding frequency over a 30 year period. They found that the species that needed urgent care were baleen whales along with common dolphins. Recommending that more research efforts should be done with these species to understand the major drivers of stranding and stress for both of these individuals.

What once was viewed as an opportunistic way of recording and documenting deaths for marine mammals is now considered one of the most effective and valuable data collecting methods for conservation efforts. It is clear that stranding data is challenging and time consuming, however its benefits greatly outweigh its challenges. Standardizing this method of data collection would be a great implementation in other stranding programs around the world and could potentially uncover unknown issues within the marine mammal kingdom.

For more information, check out the original scientific paper:

Lennon, R. L., Williams, R. S., Allan, K. J., ten Doeschate, M. T. I., Davison, N. J., Babayan, S. A., & Brownlow, A. C. (2025) An approach to using stranding data to monitor cetacean population trends and guide conservation strategies. Scientific Reports, 15:28417.

Killer whales are known to regularly attack and kill baleen whales, specifically their calves. So there has to be way that baleen whales protect or defend their calves, but how? Well, in a research paper by Trevor A. Branch there is something called the flight or fight hypothesis, which is where some mama baleen whales stand their ground and stay to defend their calf from the killer whale (fight) and then there are some mamas that don’t want to risk it and flee (flight).

The whales that are in the fight groups are the North Atlantic right whales , southern right whales, bowhead whales, humpback whales, and grey whales – woo go them ! And those in the flight groups are the blue whales, fin whales, sei whales, common minke whales, Antarctic minke whales and Bryde’s whales.

In Trevor’s paper he focuses on acoustic crypsis, which means that an animal uses sounds or lack thereof to hide from predators, making them hard to detect by ear. The flight whales deploy acoustic crypsis as a defense mechanism against the killer whales so that they can’t find them, really cool I know!

The biggest flight members, the blue and fin whales, are acoustically invisible to killer whales. The blue whales produce the loudest and lowest frequency, typically falling below 80Hz ( 80Hz is comparable to the core bass range of a guitar).

And the fin whales call can go even lower than the blue whales, never exceeding 99 Hz (99 Hz is comparable to a very deep musical note). These low notes cannot be heard by killer whales, meaning killer whales can only detect blue and fin whales by visual sightings, or the sounds of their blows or splashing, but never acoustically through their songs.

The data in Trevor’s research supports the hypothesis that the flight group are more acoustically cryptic than the fight group. The hypothesis that fight species that sing at a higher frequencies are more easily detected by killer whales, than the flight species who are and should be acoustically cryptic does appear to work for most species.

Meaning that the flight species can get away from killer whales and can communicate with each other without the killer whales hearing them, meaning that the flight group takes the win, yay!

For more information, check out the original scientific paper:

Branch, T.A. (2025) Most “flight” baleen whale species are acoustically cryptic to killer whales, unlike “fight” species. Marine Mammal Science, 41: e13228. https://doi.org/10.1111/mms.13228

Baleen whales migrate from Antarctica to Colombia for the breeding season and do not eat during the journey north towards their breeding grounds. This is because they are capital breeders, which means they eat a lot of food at the start of their journey and store it to be used during the migration and breeding process. For Humpback whales, their main source of food in Antarctica is krill. Antarctic krill is a keystone species in the Antarctic Ocean, with many species relying on it for food. Scientists used the estimated amount of body fat lost during migration to estimate the energy used and then estimated how much krill is needed to provide that amount of energy.

To find out the total energy loss the scientists used drones to take photos and videos of the whales throughout their migration to Colombia. The use of drones allows the Scientists to easily track and track photos of the whales. The photos that were taken by the drones were used to create models of the whales, helping them track their body mass and how much it changed from the Antarctic Oceans to the coast of Colombia. The whales seemed to have fattened up before they left the Antarctic Sea. Once the whales reached the breeding grounds, they seemed to have lost around 36 percent of their body fat, which is about eleven thousand kilograms of blubber. That amount of blubber works out to be about 196 million kJ of energy, the whale would need about 57,000 kg of krill to produce that much energy.

With the current rate of global warming the krill population will be reduced to devastating amounts by 2100, where there won’t be enough to sustain the ecosystem in the Antarctic Ocean. After the predicted date of 2050 for the humpback whales to recover from whaling, they will end up short on food and the populations will begin to decline again.

For more information, check out the original scientific paper:

Bernier-Graveline, A., Nash, S.B., Bierlich, K.C., Friedlaender, A., Johnston, D.W., Castrillon, J., Botero-Acosta, N., Caballero, S., & Christiansen, F. (2025). Drone-based photogrammetry provides estimates of the energetic cost of migration for humpback whales between Antarctica and Colombia. Marine Mammal Science, 41:e70048. https://doi.org/10.1111/mms.70048

North Atlantic Right Whale (NARW) distributions are a valuable tool utilized in conservation efforts for monitoring this Critically Endangered species. Right Whales feed primarily on Calanus finmarchicus, a calanoid copepod that is typically found in abundance and can provide a sufficient source of energy for the Right Whale. This study explores the possibility of more efficient monitoring through the utilization of Density Surface Modeling (DSM). If researchers can accurately predict where the abundance of C. finmarchicus is, this may lead to discovering the foraging pattern of Right Whales.

DSM is the process of mapping, in detail, an estimate for a species abundance based off distance sampling which uses more estimates of abundance from a given area. In this case, it is being utilized to estimate right whale density using a combination of set variables such as depth, surface temperature, multi prey abundance exceeding a designated amount, etc. Right Whales are typically monitored through visual aerial or ship surveys; however, this leaves a large gap in spatial and temporal coverage leading to spotty detection probability. Incorporating prey distributions and the many covariates into DSMs can potentially improve predicted whale distribution and provide a more cohesive interpretation by determining if movement is prey driven and provide a spatial outline for where those locations may be.

To properly examine this possibility, the researchers tested different prey and prey proxy covariates (depth, temperature, abundance probability) to represent prey within a right whale DSM. Then, determined the relationship that aligned with each prey or prey proxy covariate and determined which covariates produced the most likely predictions. “The top-performing model included a combination of covariates representing high-density C. finmarchicus, Centropages typicus, and Pseudocalanus spp. aggregations and resulted in density predictions consistent with the observed distribution patterns of Right Whales.” (Ross 2025).

At this point you might be asking yourself, why go through all this effort? Right Whales are critically endangered and have in recent years become a major conservation issue due to their association with regional fisheries, specifically the Maine and Canada lobster fishery. As states previously are tricky to locate and tracking strictly visually can be difficult so, adding a method that can use more efficient prediction could prove more of a viable option for efficient tracking.

The predicted density was most commonly found in the deep basins of the Gulf of Maine, as well as the Great South Channel. The density changed through the seasons, as predicted, increased in the summer, and decreased in the winter. This is common with the known foraging behavior of the Right Whale. As it stands now, NOAA’s Atlantic Large Whale Take Reduction Team is developing and including these covariates in decision making tools in an effort to aid management goals. Maintaining consistent monitoring of prey resources and development/changes of prey fields is necessary for models to successfully assist in the conservation of these endangered marine predators.

For more information, check out the original scientific paper:

Ross, C. H., Roberts, J. J., Pendleton, D. E., Brady, D. C., Stamieszkin, K., & Record, N. R. (2025). Incorporating prey fields into North Atlantic right whale density surface models. Endangered Species Research, 58, 67–84. https://doi.org/10.3354/esr01435

Tourists come to watch whales. But new research shows that the watching itself may be wearing whales down.

Southern Right Whales are large, slow-moving whales that migrate to calm coastal waters each year. Mother-calf pairs need long periods of quiet rest and low-energy behavior to survive and grow. Whale watching brings boats up close to these whales, which scientists are growing increasingly worried about the impacts that this has on these slow giants.

A new study published in 2025 looked at how whale watching impacted the behaviors of the southern right whales. The study took place in coastal waters off Argentina, where southern right whales gather to give birth and raise their calves. This limit
if popular for whale watching but has limitations to how close boats can get and how long they can stay near whales. Because of these protections, they provided ideal conditions for the researchers to study the whales under controlled conditions. The researchers observed groups of whales with and without whale watching vessels present. They recorded changes in their activity, movement, and social behavior. They would use this data to calculate the time lost from acting on important behaviors after having whale watching vessels present.

Whale watching was seen to significantly alter the behavior of the whales. When the whale watchers were present, whales spent less time resting and more time swimming, diving, or other energy costly behaviors. The mother and calves were extra sensitive; there were sharp decreases in calm stationary behavior. The whales were even seen to stop all social interactions when vessels were there.

With the conditions the whales were observed, the researchers decided that the whale watching boats in the area are below the danger limit. The whale watching industry is growing, which brings concerns for scientists that this could exceed the danger limit in the future.

This study is sending a message that as whale watching expands globally, one of the simplest and most effective ways to support their recovery is to give them more space. Whale watching is not harmful right now, but without limits, whale watching can be harmful. The study found that the behavior is impacted by whale watching, but the number of boats in the area is still low enough that whales can handle it. Though, if whale watching numbers increases without care and rules, these changes could become harmful. Tourists can still view the massive animals, but at a more respectful distance.

For more information, check out the original scientific paper:

Arias, M., Dans, S., Crespo, E.A., & González, R.A.C. (2025) Southern right whale behavioral changes due to interactions with whale-watching vessels: evidence-based calculations aimed at improving management policies. Marine Mammal Science, 41: e13149. https://doi.org/10.1111/mms.13149

With the worsening issue of climate change comes extreme events like marine heatwaves. In some incidents, these extreme events can lead to changes in whole ecosystems as well as those neighboring them. In the case of this recent study, a marine heatwave led to the almost complete loss of a species of rocky intertidal sea stars which are considered a keystone species in that environment. A species is considered a keystone when their existence in an environment is very important. For example, an elephant is considered a keystone species because they eat trees so that they don’t overtake grasslands. Sea stars in this rocky intertidal environment have a similar role in which they eat the mussels that grow on the rocks so that their population stays in check. The loss of these stars led to the growth in the population of mussels, which caused changes in their ecosystem and neighboring ecosystems as well.

In 2013 a marine heatwave in Monterey Peninsula, CA. caused rocky intertidal ecosystem temperatures to rise higher than a local sea star population could tolerate, and many, if not most of these sea stars died as a result. These sea stars were the main natural predators of mussels growing on the rocks where they lived. With their main natural predator gone, the mussel population boomed and spread down the rocks way past the original range controlled by the sea stars. Another keystone species, sea otters, were living and feeding in the neighboring environment of the coastal waters. Their population had not fluctuated much over the past decades prior to the marine heatwave. After many of the sea stars died, the mussels grew in size and took over the rocks. After some time, the sea otters ended up eating many more mussels than before since there was a surplus. Because there was so much more food available, the population of sea otters was able to grow.

You may be thinking that this could be a good thing. If there are more mussels for the sea otters to eat, their population will grow, and with more otters they will take the place of the sea stars and keep the mussel population in check, right? Unfortunately that isn’t quite the reality of what happens in this scenario. When the sea stars were around, they had a main role in keeping the mussel populations in check so that they didn’t overtake the many other different kinds of species like other shelled animals, barnacles, anemones, and kelp that live with them. The otters have a similar role in keeping the species in their own environment, like sea urchins, crabs, and clams in check. The loss of the sea stars means that the mussels were able to take over the rocky intertidal environment, not allowing the other species in that habitat the room to live. Even though the sea otters were able to eat a lot of mussels, they cannot efficiently take care of controlling the populations for both distinct environments. For example, their movement to mussels for food allowed sea urchins to spread rapidly across the kelp forests. There they munched through much of the kelp forests, leaving them with less and less of the kelp that many creatures use to live, eat, and survive. This event shows that the loss of one species, big or small, can have large and lasting effects in their ecosystem, but also others. Each animal has a role to play in their environments, and even if they may seem insignificant, they could have major impacts on the function of the habitats around them.

For more information, check out the original scientific paper:

Smith, J.G., Fujii, J.A., Gaddam, R., Konrad, L., Lyon, S., Nicholson, T.E., Raimondi, P.T., Ridlon, A.D., Staedler, M., Tomoleoni, J.A., Yee, J.L., & Tinker, M.T. (2025). Keystone interdependence: Sea otter responses to a prey surplus following the collapse of a rocky intertidal predator. Science Advances, 11:1028. https://doi.org/10.1126/sciadv.adu1028

Sea otters spend nearly all day diving and consuming thousands of calories to fuel their energetic lives. So, it seems reasonable to assume that oyster farms – packed with easily accessible prey – would draw their attention. But a recent study from Kachemak Bay, Alaska, found that sea otters largely overlook oyster farms altogether, and their behavior remains surprisingly consistent whether farms are present or not.

Researchers spent two summers observing sea otters at several mariculture sites and nearby areas without oyster farms. They tracked what the otters ate, how often they foraged, and whether farm structures affected their behavior. Given how heavily sea otters depend on shellfish for food, many expected the otters to take advantage of the dense clusters of oysters grown on farms. Surprisingly, despite the tempting buffet of farmed oysters, otters stuck to their usual diet: clams, crabs, and mussels dug up from the seafloor. Not a single farmed oyster was seen being eaten during the study.

There was one small exception: at one farm that also grew mussels, a few otters were spotted nibbling mussels attached to buoys and grow lines. These limited interactions suggest that otters may occasionally take advantage of certain types of farmed shellfish under the right conditions. In fact, some otters even removed unwanted mussels from farm structures – essentially doing farmers a favor by performing a type of natural cleaning that the farmers would typically have to do themselves.

So why aren’t otters munching on the oysters that seem so easy to reach? The researchers suggest it could be related to taste, texture, or long-standing feeding habits. Otters may prefer the more familiar and naturally foraged prey, even when more convenient options are available.

Overall, the study paints a hopeful picture for both wildlife and aquaculture. Sea otters and oyster farms appear to coexist with minimal conflict. Otters continue to thrive and forage successfully, while oyster farms remain largely untouched. As Alaska’s mariculture industry grows, these findings offer reassuring baseline information: the predicted clash between hungry sea otters and farmed shellfish may not be as dramatic as once imagined – and in some cases, otters may even help farmers out.

Understanding this relationship matters not just for conservationists, but also for the general public. Healthy sea otter populations indicate a thriving marine ecosystem, while stable oyster farms support local economies and sustainable seafood. For now, it seems these two unlikely partners are finding a way to share the coast.

For more information, check out the original scientific paper:

Reynolds, E., Konar, B., Horstmann, L. (2025). Sea otter interactions with mariculture oyster farms. The Journal of Wildlife Management, 89:e70055. https://doi.org/10.1002/jwmg.70055

A recent study used drones flying high above the ocean to capture the first detailed views of Pacific white-sided dolphins and Dall’s porpoises deliberately approaching and swimming with northern resident killer whales near northeastern Vancouver Island. Instead of showing scenes of pursuit or danger, the footage presents calm, sometimes playful interactions that challenge our assumptions about predator-prey relationships in the sea.

Scientists recorded 42 encounters between two smaller cetaceans (marine mammals like whales and dolphins), species and fish-eating northern resident killer whales between 2018 and 2021. Significantly, these interactions were never started by the killer whales. Rather, the whales were approached by dolphins and porpoises, sometimes spending over an hour in their company.

Why risk it? The study’s list of potential benefits prioritizes predator protection. Bigg’s killer whales are an ecological group that hunts dolphins and porpoises, whereas resident killer whales consume seafood. Swimming with resident killer whales may offer a brief “safe zone” from their actual predators.

Additionally, the study revealed distinct species differences. Dall’s porpoises tended to move swiftly through killer whales and only interacted with small groups (five or fewer). On the other hand, dolphins frequently joined considerably bigger groups—sometimes over 25 killer whales—and stayed longer. Dolphins were often observed swimming next to or slightly ahead of whales, which may conserve energy and reduce drag—similar to how a car uses less fuel when driving behind a large truck that pushes air out of the way.

Occasionally, interactions appeared social. Young killer whale calves were seen playing with dolphins and porpoises. Mildly aggressive behaviors, such as tail slaps, were rare and usually didn’t end their interactions. Also, note that some underwater interactions may have gone unnoticed because observations were limited to surface drone footage.

Overall, the study’s findings show how new drone technology is transforming our understanding of marine life by revealing subtle behaviors that are difficult to see from land or boats. While killer whales seem to gain little from these interactions, dolphins and porpoises might benefit from safety, energy savings, and educational opportunities.

Even top predators can become unlikely allies.

For more information, check out the original scientific paper:

Visona-Kelly, B.C. & Barrett-Lennard, L.G. (2025). The foe you know: Observations of interspecific interactions between small cetaceans and northern resident killer whales (Orcinus orca) in the Northeast Pacific. Ecology and Evolution, 15:e71444. https://doi.org/10.1111/mms.13010

A Clear Sign the Ocean is Changing

Scientists studying harbor seals in the Skagerrak, a sea region between Norway and Sweden, have discovered a major shift in what these animals eat. Compared to past decades, harbor seals today are eating very different fish than they once did. This change may be an important warning sign that the marine ecosystem in this region is changing.

Researchers found that harbor seals have shifted away from larger, energy-rich fish toward smaller species that provide less nutrition. Because seals rely on the same fish species that support commercial fisheries and other marine predators, changes in their diet can reveal broader problems in the changing environment, and seals are being forced to adapt. Watching what seals eat helps scientists understand the health of the sea and may help protect these animals and their habitats in the future.

What Are Harbor Seals Eating Today?

To understand seal diets, scientists collected seal scat (feces) from small rocky islands along the Norwegian coast. Inside the scat, they found tiny fish ear bones called otoliths. These bones are unique to each fish species, allowing researchers to identify exactly which fish the seals consumed.

The results showed that modern harbor seals primarily eat smaller fish such as sandeels and Norway pout. These fish are more abundant and easier to catch, but they contain far less energy than the fish seals depended on in the past.

How Have Seals’ Diets Changed Since the 1970s?

When researchers compared recent samples to studies from the 1970s and 1980s, a clear pattern emerged. In earlier decades, harbor seals consumed large, energy-rich fish such as herring and cod. These fish supported healthy body size, reproduction, and pup survival.

Over time, heavy fishing pressure and environmental changes have reduced populations of these larger fish in the North Sea. As these preferred prey species became less available, seals gradually shifted their diets to whatever fish remained abundant. Recent studies show that seals in this region are now smaller and producing fewer pups, likely due to reduced nutritional intake.

Why This Helps Us Understand the Ocean

Harbor seals are considered sentinel animals, meaning they act as early warning indicators of ecosystem health. Because they are long-lived predators that depend on local fish populations, changes in their diet often reflect larger shifts happening throughout the marine food web.

By studying what seals eat, scientists gain insight into declines in fish populations, ecosystem imbalances, and the long-term impacts of human activity on the ocean. Monitoring seal diets helps researchers understand how marine environments are changing and may guide future conservation and fisheries management efforts.

Why Seals Matter

Harbor seals provide valuable information about ocean health that might otherwise go unnoticed. When their diet, size, or reproduction changes, it signals that conditions in the marine ecosystem are also changing. Paying attention to these signals can help scientists protect marine habitats before damage becomes irreversible.

For more information, check out the original scientific paper:

Kappa, F., Härkönen, T., Freitas, C., Carroll, D., & Harding, K. C. (2025). Shifting harbor seal (Phoca vitulina) diet may reflect ecosystem changes in Skagerrak. Marine Mammal Science, 42: e70069. https://doi.org/10.1111/mms.70069

For many species of baleen whales, migration is not just the movement to mark the shift from feeding to reproduction, but it is a transport of nutrients that feed ecosystems across the ocean. This process, observed by Joe Ramon and others for Nature Communications, begins with high-latitude feeding zones, where baleen whales will consume large amounts of nutrients to store large amounts of energy. Once enough energy has been accumulated, these baleen whales travel to lower latitudes, sometimes tropical reproductive grounds. These distances are often greater than the migrations of other marine mammals; for example, gray whales feed off the coast of Russia before traveling 11,000 km to reproductive grounds along Baja California. These migrations go across several ecosystems, and along the way excretion from gray whales, or other migratory baleen whales drop traces of carbon and nitrogen towards the seafloor. This transport provides necessary macronutrients for life to occur within the ocean’s depths, and with the distance many baleen whales travel during migration, they provide far more than other migratory species.

This act of migration not only works for ecosystems, but also for the baleen whales themselves due to the benefits that come in warmer reproductive zones. In the high-latitude feeding zones many predators, like orca whales, feed on whales, and the offspring lack the necessary experience to avoid intense predation. Safety is not the only benefit, however; warmer waters provide whale calves with a more suited environment to grow and develop faster. Until the calves develop blubber to better withstand the colder waters at higher latitudes, these reproductive grounds provide both safety and quicker growth for whale calves. During the feeding of calves, mothers provide even more nutrients to the ecosystem, and with these migrations occurring around 20 times per lifetime, it shows how much baleen whales provide for ecosystems during migration.

The impact that baleen whales have from migration is undeniable. Despite just how much baleen whales contribute to ecosystems during migration, however, their contributions used to be far greater. Because of commercial whaling, their populations have dropped significantly across the globe. Without stronger protection methods in place for whales to recover in size, like protected areas, modified fishing gear, and greater whale monitoring habits, the spread of vital macronutrients across these long migration patterns will only decline. Not only does this impact baleen whales, but also every species across the ecosystems that benefit from these nutrients. The migration of baleen whales not only aids in protecting their calves but also in the growth of
ecosystems across the ocean. Roman and his fellow researchers called for an increase to whale recovery, not just for the whales, but for ecosystems everywhere impacted by their essential migrations.

For more information, check out the original scientific paper:

Roman, J., Abraham, A.J., Kiszka, J.J., Costa, D.P., Doughty, C.E., Friedlaender, A., Hückstädt, L.A., Marcondes, M., Wetsel, E., Pershing, A.J. (2025). Migrating baleen whales transport high-latitude nutrients to tropical and subtropical ecosystems. Nature Communications, 16, 2125. https://doi.org/10.1002/ece3.71193

Harbor seals are arguably the cutest and most recognizable marine mammal in northern waters. These charismatic creatures are well known for their curious and often lazy demeanor, as you can usually spot them relaxing in groups along the rocky coast or swimming close to shore.

A recent study conducted by Kappa et al. (2025) revealed interesting connections between the diets of Swedish harbor seals and a changing food web, using historical data to track long-term trends. To understand the seals’ diets, scientists analyzed seal scat, or poop. While most materials break down during digestion, fish ear bones remain intact. These ear bones are unique to each species and allow researchers to identify which fish the seals consumed.

Samples collected in 2020 were compared with datasets dating back to the 1970s and 1980s. By counting and identifying ear bones from different time periods, the researchers were able to track changes in the availability of fish species over several decades. However, researchers acknowledged that the assessment of scat is challenging, as some of the samples get washed away or deposited in the open ocean. Despite these obstacles, the researchers worked to collect samples across different sites and times to reduce bias as much as possible.

Their findings showed a clear shift in diet. While some key species such as sandeels and gadoids remained constant over time, other high-energy fish that once played a major role in seal nutrition, like cod and herring, declined sharply. These species are not only important for seal health but also for local fisheries and human consumption. A drop in their presence suggests broader changes occurring in the marine food web.

Overall, the study highlights how changes in seal diet can serve as an early warning sign of ecosystem shifts. As fish communities continue to change, ongoing monitoring and conservation efforts will be essential to understanding and protecting marine wildlife and the human industries that depend on a healthy ocean. Stricter regulations on catch limits and no-fishing zones, known as Marine Protected Areas, may help the cod and herring populations recover. Yet without decisive action, the foundation of the ecosystem remains unstable. The charismatic and widely loved harbor seal must serve as a flagship species for conservation efforts like these, helping capture public attention and support for broader ocean protection efforts.

For more information, check out the original scientific paper:

Kappa, F., Härkönen, T., Freitas, C., Carroll, D., & Harding, K. C. (2025). Shifting harbor seal (Phoca vitulina) diet may reflect ecosystem changes in Skagerrak. Marine Mammal Science, 42: e70069. https://doi.org/10.1111/mms.70069

Summary: The following podcast discusses a study that examines the interactions between Dall’s porpoises, Pacific white-sided dolphins, and resident orcas in the Northeast Pacific.

For more information, check out the original scientific paper:

Visona-Kelly, B.C. & Barrett-Lennard, L.G. (2025). The foe you know: Observations of interspecific interactions between small cetaceans and northern resident killer whales (Orcinus orca) in the Northeast Pacific. Ecology and Evolution, 15:e71444. https://doi.org/10.1111/mms.13010

A new study finding reveals that Atlantic bottlenose dolphins cut their noise level extremely low when they eject large pockets of air through their blowholes. In two separate studies that recorded over 700 bubble events, researchers observed that these large clouds of air are accompanied by an abrupt decline in sound, particularly, the whistles and high pitched pulsing calls dolphins use when socializing and exploring.

Dolphins use sound as a primary way to communicate, navigate, and organize with each other. The fact that the bubble burst periodically disrupts that communication, might be significant in the ways dolphins speak or signal to one another.

The researchers observed 11 dolphins in San Diego bay California, and compared the sound level of each bubble burst with the two seconds immediately preceding it. They discovered that in general, levels of noise were reduced significantly during the bursting of the bubble, but especially whistles and fast pulsing sound.

Researchers assume that the burst temporarily releases the pressure in the nasal system, thus, making it harder to vocalize until the normal pressure is restored. But why do dolphins utilize the bubble burst to begin with?  The results of the studies do not provide, but it is believed by the researchers that the silence and the big bubble itself might be a part of their communication. This opens doors for new experiments to be conducted on the  when, where, and why dolphins choose to deploy this unique burst of air, and potentially we will gain more insight as to the ways these fascinating mammals speak to each other in the near future.

For more information, check out the original scientific paper:

Miller, E.C., Royse, C.D., Harris, C.R., & Johnson, C.M. (2025). Evidence for a decrease in vocalizations during bubble burst production in Atlantic bottlenose dolphins (Tursiops truncatus). Marine Mammal Science, 41:e70049. https://doi.org/10.1111/mms.70049

What do you get when you mix two similar species in the same area? In the case of the harbor porpoise and the bottlenose dolphin, you end up with a slew of problems and a struggling species. Bottlenose dolphins are not necessarily predators of harbor porpoises; however, they tend to exhibit aggressive tendencies toward the porpoises, especially during the breeding season and periods of high testosterone levels. Typically, in areas with habitat overlap between dolphins and porpoises, we observe more audio activity from harbor porpoises when dolphins are not active, and less activity when dolphins are active and present. Areas where dolphins are typically not at, such as the Baltic Sea and the inner Danish waters, are starting to see dolphin migration to those areas due to human disturbance in their original territory. The pre-existing porpoise populations in these areas had not had experience dealing with dolphins, so they began to see more aggressive attacks against them. Scientists wanted to find the presence of bottlenose dolphins and harbor porpoises in the Baltic Sea around Funen, Denmark. Their methodology to obtain presence data was to release an app that allows people to report their encounters with harbor porpoises around Funen. They also used acoustic data to quantify porpoise and dolphin presence in the area. The acoustic data that was collected were the animal’s echolocation chains. These echolocation chains are small clicks and sounds that the animals use to hunt and find food. The results of the study showed that there were fewer porpoise sightings and audio detections wherever dolphins were present; however, an increase in audio detections was found where dolphins had not been reported. This could show us that the porpoises are retreating to these areas without dolphins out of fear of these animals bullying them. This could imply that porpoises are migrating as well as the dolphins. Studying these migration trends could help us protect native species from invasive predators such as dolphins. Being able to locate species with the audio recordings could also help us locate where certain animals or populations are heading and where they are leaving.

For more information, check out the original scientific paper:

Filatova, O.A., Fedutin, I.D., Jakobsen, F., Kindt-Larsen, L., & Wahlberg, M. (2025) Harbor porpoise displacement by a solitary bottlenose dolphin in the Baltic Sea. Marine Mammal Science, 41:e13164. https://doi.org/10.1111/mms.13164

Scientists along California’s Monterey Peninsula have discovered a surprising chain reaction in the ocean after a starfish almost disappeared. In 2013, a fast-spreading sickness called sea star wasting disease devastated populations of the starfish Pisaster ochraceus, a species long recognized for its role in controlling mussel populations in rocky tidepools. However, when these sea stars began to get sick and die, mussels became more abundant, got bigger, and spread into lower tidal areas more than they had before the collapse, reshaping the structure of the shoreline. These changes helped mussels become easier for other animals to find. One animal that took advantage of this change was the sea otter.

Sea otters – playful marine animals, known for being entertaining – typically forage in nearby kelp forests, feeding on various sea creatures such as sea urchins, clams, and crabs, but when mussels became more common, otters began eating them more often. Using long-term foraging observations and a detailed statistical model, scientists found that otters ate two to three times more mussels than before, which gave them more energy in less time. This extra energy helped the sea otters stay healthy, take care of their babies, and survive better, leading to a gradual rise in the local sea otter population.

The scientists describe this pattern as “keystone interdependence”, a process where the decline of one keystone species can indirectly affect another by changing the flow of energy across connected ecosystems. In this case, the collapse of the Pisaster ochraceus allowed mussels to expand, increasing the available energy in the shoreline, leading sea otters to shift their foraging behavior and focus more heavily on mussels near shore.

This study highlights how the near disappearance of sea stars led to big changes along the California coast. When sea stars became sick and died, mussels were no longer kept in check and spread into new areas. This made mussels easier for sea otters to reach, causing them to change what they eat, gain energy, and slowly increase in number. These changes show how a disturbance in one habitat can reshape species interactions in entirely different areas. As climate change increases, and extreme events such as diseases become more common, protecting keystone species and monitoring their populations becomes more important than ever.

Understanding these connections helps scientists and conservation groups such as the Monterey Bay Aquarium, work to protect ocean ecosystems by researching marine animals and teaching people how to care for the ocean, take action earlier, strengthen ecosystems, and prevent future collapses before they happen.

For more information, check out the original scientific paper:

Smith, J.G., Fujii, J.A., Gaddam, R., Konrad, L., Lyon, S., Nicholson, T.E., Raimondi, P.T., Ridlon, A.D., Staedler, M., Tomoleoni, J.A., Yee, J.L., & Tinker, M.T. (2025). Keystone interdependence: Sea otter responses to a prey surplus following the collapse of a rocky intertidal predator. Science Advances, 11:1028. https://doi.org/10.1126/sciadv.adu1028

Off the coast of Scotland there is an eerie scene, of large heavy corpses rotting and filling the beach. We must respond to this scene with tactics of investigation and future planning of prevention to find a solution to this unknown problem.  A marine mammal is an animal like a whale or dolphin that has hair and feeds their young breast milk and marine is sea so its a sea mammal. An alarming number of these whales have shown different trends in this study on their population (Lennon, R.L et al.2025). The coast of Scotland has been having an increase in the number of beaching’s that a lot of whales, dolphins, and porpoises have experienced.  Beaching occurs when marine mammals would wash ashore where they would die as they can’t move their bodies on land, or their death occurs at sea and leads to them washing ashore. The marine mammals end up harmed by things like getting warped up in old nets and disoriented by noise from large ships.

To get to the bottom of this, the study from the Scottish scientists looked at the beaching’s and kept track of mortality rate. Mortality rate would be the number of beached animals that can be found over the course of a long time like a 30-year data set. The researchers looked at the seasonal count of beaching’s from 1995-2020 over the course of 12 months. To record and assess this data the study looked at 5147 marine mammals: whales, dolphins, and porpoises. The species in the study found on the beach showed a trend of frequently increasing over the years. The most notable species that were suffering from crashing onto the beach were whales and dolphins who had a greater increase out of all marine mammals.  This was the start to the most viable information, and it helped us keep track of marine mammals so we could be ready to help them when they need aid.

Tracking the marine mammal’s population and beaching gave us the knowledge that the marine mammals have been on a decline from beaching for many years. The next step after this is to work on conservation efforts and build a strategy to fight against this declining population. Conservation is very important as it means to preserve and prevent a quantity such as a resource or in this case an animal. Using more science and statistical data analysis can help us strive to preserve valuable nature in our world, especially one that has been connected and suffered from humans. Keeping an eye on nature helps us know what is going on currently and can be useful for us all to prepare and fight against threats that harm animals but also us. To keep the world prepared, keeping track of its situation should be the first step towards a solution that keeps us focused on maintaining a stable environment.

For more information, check out the original scientific paper:

Lennon, R. L., Williams, R. S., Allan, K. J., ten Doeschate, M. T. I., Davison, N. J., Babayan, S. A., & Brownlow, A. C. (2025) An approach to using stranding data to monitor cetacean population trends and guide conservation strategies. Scientific Reports, 15:28417.

A new study from researchers in Denmark has documented that harbor porpoises, a beloved species of marine mammal, are being attacked and displaced in the Baltic Sea by newly present bottlenose dolphins. Many deceased porpoises have been found washed up on shore with dolphin-inflicted wounds, and data have shown that porpoises disappear when a dolphin moves in. Researchers worry that despite the fact that dolphins don’t consume the porpoises they kill, they may have the same negative impact as invasive predators.

Dolphins have not historically lived in the Baltic Sea, so Danish porpoises likely aren’t used to sharing waters with the potentially dangerous animals. In places where both species coexist, such as California and Scotland, dolphins are known to harass and kill porpoises. It’s been observed that male dolphins carry out these attacks during breeding season, so scientists theorize that the behavior is a type of unfortunate aggressive play for frustrated dolphins. Because of this, the researchers knew there could be a link between porpoise deaths in the Baltic Sea and the presence of a lone male dolphin.

Importantly, porpoises that share overlapping habitat with dolphins are known to avoid potential aggressors. The Danish researchers, led by Dr. Olga Filatova of the University of Southern Denmark, wanted to find out whether porpoises not used to living with dolphins—or being attacked—had the same response. They set out to investigate this using special underwater microphones that are tuned to pick up the high-pitch clicking noises that dolphins, porpoises, and other marine mammals use to hunt and communicate. With these acoustic detectors, they could identify dolphins or porpoises in an area and estimate their abundance. They found that harbor porpoise acoustic detections substantially decreased in the areas inhabited by the bottlenose dolphin.

The study acknowledges that using acoustic detection has key shortcomings. Because they were relying on sound to measure porpoise presence, they can’t be sure of the extent to which porpoises are fully leaving the area. It’s known that they also go quiet to avoid being heard by dolphins. Still, this change in behavior is negative for the porpoises, since they rely on making noise to find food and communicate.

The researchers warn that potentially declining porpoise populations are threatened by attacks from dolphins, and that fearful porpoises may be avoiding better habitats. This is known as creating a “landscape of fear”. Great white sharks and killer whales are also known to drive these disruptive fear-based responses in porpoises and other animals.

Overall, the study team says that more work is needed to fully understand the ecological impacts this potential “landscape of fear” may have. While the number of dolphins in the Baltic Sea is currently too low to have a strong impact, researchers believe that dolphins will increasingly move in as they lose habitat elsewhere. Because of this, the best way to protect these beloved Danish porpoises may be to work to conserve dolphin habitats elsewhere.

For more information, check out the original scientific paper:

Filatova, O.A., Fedutin, I.D., Jakobsen, F., Kindt-Larsen, L., & Wahlberg, M. (2025) Harbor porpoise displacement by a solitary bottlenose dolphin in the Baltic Sea. Marine Mammal Science, 41:e13164. https://doi.org/10.1111/mms.13164

About fifteen years ago, the Deepwater Horizon oil spill devastated the Gulf of Mexico. Roughly 134 million gallons of oil was spilled, which the environment is still struggling to recover from to this day. Since then, oil spill prevention and cleanup plans have been important for coastal countries to formulate and properly execute.

In February 2025, a study on a possible response plan for oil spills was published from New Zealand. The island country, which has about 15,000 kilometers of coastline and 75 percent of its major population on the coast, relies heavily on water transport of goods and oil. This increased reliance on water transportation is due to the closure of the only refinery in the country in 2022, elevating possible oil spill risks dramatically. This study focused specifically on the recovery of the New Zealand Fur Seal (referred to as NZFS), a type of pinniped, in the event of an oil spill because of its ecological, cultural, historical, and economic significance.

Pinnipeds are a scientific grouping of marine mammals that contain seals, sea lions, and walruses. They typically rely on a layer of fat, called blubber, to stay warm. However NZFS are unique because they do not rely on blubber, but their fur for insulation. This makes these animals much more vulnerable to oil because their dense fur becomes matted and can no longer keep them warm. The NZFS is also difficult to rehabilitate after a possible oil spill because of their massive size and aggressive behavior, so when creating a protocol, prevention is more effective than management.

However, to create a proper prevention strategy, it is important to know the population size of the species in question. Despite being an important animal, there was no official or reliable population estimate for the entire country of New Zealand. The study, performed by Massey University and New Zealand’s Department of Conservation, had the goal of providing that lacking information, with a focus on pup counts to determine breeding success.

The researchers determined that the NZFS population is getting larger, especially within the areas of New Zealand that are considered high risk for oil spills. In fact, they determine that the population sizes are dramatically larger than previously thought, and new populations have appeared and grown since the last known population estimate. With this new found population size, determined by counting pups and the use of a formula called Petersen pup production estimate, the researchers were able to provide possibly effective methods of preventing animals from being oiled.

They determined that the highest priority in the event of an oil spill is to keep the oil away from land, where most of the NZFS pups would be located. The researchers also suggest sound and small explosive deterrents for the fur seals in the water at the time of an oil spill, but there is a risk that the animals will simply ignore them, and swim into the oil regardless. The study concludes with a call to action; to create a consistent monitoring program of the NZFS population for the purpose of planning effective oil spill responses, as well as other concerns, such as climate change.

For more information, check out the original scientific paper:

Hall, A.A., Chilvers, B.L., & Weir, J.S. (2025). Planning for a pinniped response during a marine oil spill. Environmental Science and Pollution Research, 32, 10929-10944. https://doi.org/10.1007/s11356-025-36192-y

Summary: In this episode of The Underwater Hour, host Braeden Victory explores the complex social structure of North Atlantic killer whales, highlighting a recent genetic study revealing clustering shaped by geography, diet specialization, and historical changes in prey availability. This discussion emphasizes the interconnectedness of the ocean ecosystem, and how research like this can inform the understanding and management of our natural world.

For more information, check out the original scientific paper:

Baumgartner, C.D., Jourdain, E., Bonhoeffer, S., et al. (2025). Kinship clustering within an ecologically diverse killer whale metapopulation. Heredity, 134: 109-119.

Despite their huge size, whales, dolphins and porpoises (collectively called cetaceans) can be incredibly difficult to monitor, or even find. This is a problem, as these animals serve as important indicators of environmental health.

When there’s a problem with their homes, cetaceans might move out completely or change their behaviors, the latter of these results can lead to mortalities or injuries. But how can we find these changes in behavior and the problems that are causing them?

One way is to monitor live individuals, but they can be difficult to find, let alone capture to take data and plant trackers. These methods are both intrusive to the animal and expensive for the scientists tasked with carrying out the monitoring.

One group of researchers, led by Dr. Rachel Lennon of the University of Glasgow, sought to use a 30-year dataset from the Scottish Marine Animal Stranding Scheme to demonstrate that data collected from stranding events (when a cetacean or other marine animal washes up on a beach) can be used to gain insight into population trends of different cetacean groups and suggest conservation strategies, despite potential biases that arise in opportunistic data collection on already dead animals.

Using a dataset consisting of mostly what the researchers call “Level A data” (or basic information like species, time, and location)  from stranding events collected between 1992 and 2022 and containing information from over 5,000 stranded cetaceans , the researchers were able to gather mortality trends across 5 groups of cetaceans. They found that all groups showed a population decline, however beaked whales and common dolphins showed sharper declines than the rest.

They were also able to find yearly trends in stranding events. Baleen whale and pelagic dolphin (dolphins that hunt in the open ocean)  stranding events peaked in the summer and porpoise strandings generally peaked between autumn and winter. Other groups’ peaks were more specific. Common dolphin strandings were most common in February, while harbour porpoises peaked in March. Harbour porpoises were also most commonly found stranded on the East Coast of Scotland, while most other groups were found most commonly on the northwest coast of the island.

But how can this research help with conservation efforts? For starters trends became immediately apparent during the analysis. The marine mammals with the steepest increases in strandings should be monitored more closely in order to find the root causes of increased mortalities. These findings can then be used to construct management plans for at risk species, with stakeholders more likely to lean toward this method due to the cost.

For more information, check out the original scientific paper:

Lennon, R. L., Williams, R. S., Allan, K. J., ten Doeschate, M. T. I., Davison, N. J., Babayan, S. A., & Brownlow, A. C. (2025) An approach to using stranding data to monitor cetacean population trends and guide conservation strategies. Scientific Reports, 15:28417.

Killer whales have been roaming the Northern Atlantic Ocean for millions of years, evolving into the highly specialized species that we know and love today. From the viral videos of killer whales sinking boats off the coasts of Spain and Portugal to movies like Free Willy, these whales have entered the homes of people around the world. They live in tight-knit family groups referred to as matrilines, in which offspring stay with their mothers for life and hunting traditions are passed between generations. These matrilines join to form larger social networks and, across broad regions, form what scientists call metapopulations.

These metapopulations are networks of interconnected groups that interact and allow for population-wide gene flow, a term which refers to the transfer of genetic material between populations. In the North Atlantic, these whales have developed an intricate ecological diversity with some whales dedicated to herring hunting and others who pursue a mixed diet of both fish and marine mammals. A recent study conducted by a team of scientists from across the globe set out to ask a simple question: does what whales eat shape how their family groups are connected?

By analyzing DNA from over 200 whales across Greenland, Iceland, and Norway, researchers unearthed a split in the genetic story. The nuclear genome, inherited from both parents, shows a broadly connected metapopulation with gene flow spanning thousands of kilometers, emphasizing that all three regions are connected. These findings imply that individuals occasionally mate across long distances and between different feeding types, maintaining a level of gene flow throughout the population. However, the mitochondrial DNA, passed down only from mothers, revealed strong regional differences, reflecting how matrilines remain faithful to their regional waters for generations. By looking at kinship, or how closely related certain individuals are, these patterns are further sharpened. The researchers discovered distinct family clusters that show how gene flow in the past decades has become uneven. One of the main food sources for North Atlantic Killer whales is the Atlantic herring, a small fish which once had two distinct populations that seasonally  overlapped with all killer whale populations in the region. However, in the 1960s these herring populations both collapsed due to severe overfishing for commercial use, a change
which halted the seasonal overlap of the populations and represented an abrupt shift in the distribution of the whale’s main prey.

The result of this study is a dynamic picture of a metapopulation held together in a delicate balance of tradition, ecology, and movement. Mixed-diet Icelandic killer whales emerged as key connectors in the metapopulations, bridging gaps between distinct regions where herring no longer did. Their role, and the diversity of feeding strategies they represent, may be vital for keeping the metapopulation genetically resilient, as low gene flow can weaken species against threats like disease. Although, as killer whales face mounting pressures from climate change, shifting prey, and human impacts, this study emphasizes the need for international management that protects both the whales themselves and their social and ecological diversity which binds their complex family networks together.

For more information, check out the original scientific paper:

Baumgartner, C.D., Jourdain, E., Bonhoeffer, S., et al. (2025). Kinship clustering within an ecologically diverse killer whale metapopulation. Heredity, 134: 109-119.

What’s a Keystone Species?

All species play important roles within the area they live in, their interactions with each other and their environment is what scientists call an ecosystem. However, within an ecosystem sometimes one species stands out a little more than the rest. Think about an ecosystem like a machine, and the species within the ecosystem the gears. The gears need to turn to make the machine run, but for all the gears to turn you need a driving gear that makes the rest turn. The driving gear is your keystone species, a species that drives important mechanics in the ecosystem, and without it, the ecosystem would stop functioning. An example of this machine and driving gear is the sea otter’s role in the kelp forest. Sea otters’ prey on sea urchins who eat the kelp. If the sea urchin population gets too high, they will consume all the kelp destroying the ecosystem. However, with sea otters eating the urchins, they keep the population at a manageable level. In a neighboring ecosystem a similar driving gear occurs. In the rocky intertidal ecosystem, sea stars prey on mussels, keeping their populations manageable so they don’t overtake the area.

Why did Sea Otters have to Step up to the Plate?

In 2013 a sea star wasting event caused a massive decline in the sea star population. A wasting event happens when a species loses a large portion of its population due to disease or an environmental factor. In this case the sea star population was hit by a disease, and as a keystone species scientist expected the ecosystem to collapse. But that did not exactly happen, the mussel population did increase, their coverage on the rocks increasing from 5.36% to 18.4%. However, something stopped the complete loss of the ecosystem. Sea otters began to travel across ecosystems and prey on the abundant mussel population. Cross ecosystem interactions are not uncommon but how one ecosystem facing a problem may affect the neighboring ecosystems remains unclear. That is what makes this circumstance interesting to ecologists. After this event the sea otter population increased as one of its food sources, the mussels, became more abundant. And when an increase in the sea urchin population occurred in the kelp forest, the sea otters were ready to face both problems. The population split its foraging efforts and began consuming both species, helping maintain and stabilize both ecosystems.

What does this Mean?

With climate-driven shifts in ecosystems, examples like the sea otter may become more common. Understanding these cross-ecosystem interactions, and how food webs may change to include multiple ecosystems, will be important when thinking about conservation and habitat protection. This study also highlights the importance of identifying and protecting keystone species. If the sea otter had not stepped up to the plate, crossed ecosystems, and started foraging on mussels, the rocky internal zone would have collapsed.

For more information, check out the original scientific paper:

Smith, J.G., Fujii, J.A., Gaddam, R., Konrad, L., Lyon, S., Nicholson, T.E., Raimondi, P.T., Ridlon, A.D., Staedler, M., Tomoleoni, J.A., Yee, J.L., & Tinker, M.T. (2025). Keystone interdependence: Sea otter responses to a prey surplus following the collapse of a rocky intertidal predator. Science Advances, 11:1028. https://doi.org/10.1126/sciadv.adu1028

No, although Atlantic bottlenose dolphins do form different types of bubbles, they do not use them for talking. A recent study observed if dolphins made noises, also known as vocalizations, while they blew bubbles called bubble bursts. Scientists had previously studied a type of bubble that dolphins created called bubble streams. They found that the dolphins were whistling during bubble streams, but when scientists listened to dolphins during bubble bursts, they realized they did not appear to vocalize or whistle.

Scientists observed that not only do these bubbles sound different, but they also look different. A bubble stream is a line of tiny bubbles, whereas a bubble burst is more like a thick bubble above their head. This caused the scientists to be curious and want to understand why and how they are different.

The study found that the bubble bursts did indeed have a decrease in whistling and amplitude. Amplitude means the strength of the noise and how loud it was. The authors of the study suggest that the decrease in whistling while blowing bubble bursts may be due to pressure. For dolphins to make the whistle sounds that you have heard before in videos and movies, requires air pressure in their nose. If you’re confused about what I mean, think back to when you have been on a plane or maybe gone over a very large hill. Have you ever started to feel pain near your ears? Well, that’s caused by air pressure. When dolphins blow bubble bursts, they use up that pressure. No pressure means no whistles.

This research matters because understanding how dolphins may or may not communicate can be used for other forms of research, such as other possible reasons for why they may not vocalize. Did these dolphins learn this? Is it being passed down? Is it to avoid predators that eat dolphins? There are many questions that people could ask; you may even have your own questions about why. Even though in this study, the scientists could not exactly identify what bubble bursts are used for, we do know now that they are intentional and that dolphins tend to stop vocalizing. This research, though small, can still have a big impact on dolphins and possibly other marine life.

For more information, check out the original scientific paper:

Miller, E.C., Royse, C.D., Harris, C.R., & Johnson, C.M. (2025). Evidence for a decrease in vocalizations during bubble burst production in Atlantic bottlenose dolphins (Tursiops truncatus). Marine Mammal Science, 41:e70049. https://doi.org/10.1111/mms.70049

Sea otters are well known for their cuddly faces, adorable behaviors, and voracious appetites. Since they frequently live in the same regions as mariculture oyster farms, one might anticipate this overlap to result in fat otters and angry farmers, but it turns out there isn’t much of a difference, according to a study by Emily Reynolds.

In Kachemak Bay, southcentral Alaska, mariculture farms produce healthy, hardy mussels in its cold, productive waters. The long-line farming technique suspends cages of oysters in the tides to grow them to market size. Seems like an easy meal for the nearly 6,000 sea otters residing there. Sea otters like to chow down on many species of clams, crabs, and mussels in shallow offshore regions, so Reynolds and her team expected them to be taking advantage of the floating smorgasbords.

Reynolds and her team from the University of Alaska Fairbanks conducted scan sampling on the sea otter population. This strategy involves examining the water surface and recording the activity of an individual sea otter through a telescope. She essentially just watched sea otters all day!

She and her team discovered that the sea otters in the area didn’t show much interest in the oyster farms compared to regions without mariculture farms. They spent the same amount of time resting and looking for food, and ate about the same amount of oysters. This may be due to the transition to using metal cages that deter slippery paws. If sea otters aren’t seemingly affecting oyster farms, then why does this matter?

Sea otters were hunted to near extinction in the Kachemak Bay region until the early 1900s for the fur trade. Sea otters are keystone species, which means their behaviors cause huge ripple effects through their ecosystems. When they’re wiped out from an area, grazing sea urchins become overpopulated and mow kelp down until there’s nothing but sand left. This destroys the habitat for the other animals that rely on kelp forests. Despite their amazing comeback, sea otters are still listed as endangered in the United States. Scientists want to ensure that oyster mariculture practices aren’t hurting their populations, and also check that sea otters aren’t dining and dashing. Maybe they just prefer free-range oysters.

For more information, check out the original scientific paper:

Reynolds, E., Konar, B., Horstmann, L. (2025). Sea otter interactions with mariculture oyster farms. The Journal of Wildlife Management, 89:e70055. https://doi.org/10.1002/jwmg.70055

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.