Category: marine mammal

Underwater cameras can give us insight on beha…

Underwater cameras can give us insight on behaviors we would rarely (or never!) get to observe otherwise. 

In this video, a humpback whale calf on the breeding grounds in Madagascar is carrying a CATS cam, a non-invasive suction cup camera. The footage shows that the whales grow up in a very acoustically rich environment (listen to all of the background noise!). Additionally, the camera captured a rarely seen behavior: suckling! This is the first time this behavior has been seen from a calf’s point of view. 

Studying the behavior of cetaceans in their natural habitat is extremely difficult. Most of their lives are spent below the surface and and because we are terrestrial mammals, we can’t easily watch what they are doing. These non-invasive suction cup tags can let us observe natural behaviors without interfering with the whales. I would very much like to see these types of cameras deployed on other social species of marine mammals, like killer whales.

Silent Killers vs Chatterboxes: Differences in…

Silent Killers vs Chatterboxes: Differences in Transient and Resident Killer Whale Communication 

There are two subspecies of killer whales that inhabit the eastern North Pacific: transient killer whales and resident killer whales. These two subspecies have not interbred for at least 250,000 years and display drastic differences in social structure, behavior, prey preference, morphology, and, interestingly, communication styles. 

Transient killer whales feed exclusively on other marine mammals, such as seals, porpoises, sea lions, and even the occasional large whale. These marine mammals have excellent underwater hearing and are able to detect transient killer whale calls from several kilometers away and display anti-predator behavior when exposed to these calls. Therefore, “eavesdropping” by potential prey is an issue for transient killer whales, and it has shaped their vocal behavior. Transient killer whales are almost entirely silent as they go about their day. They only become vocal in two instances: after they have made a kill, and when they are participating in surface-active, social behaviors. 

Resident killer whales, on the other hand, only feed on fish. Salmonids, their preferred prey species, have very poor hearing at the frequencies in which killer whales communicate. Therefore, resident killer whales are often loud, chatty, and can be generous in their use of echolocation calls. 

There are three types of vocalizations used by killer whales: clicks, whistles, and pulsed calls. Clicks are used during echolocation and help whales orient themselves and locate prey. Whistles are used for socialization and in short-range communication. Pulsed calls are the most common form of killer whale vocalizations; they are used in group recognition and coordination of behavior. These calls are used by biologists to distinguish individual groups of whales. 

During studies of resident and transient communication, researchers find that residents produce pulsed calls at a higher rate than transients. One study, published in 2005, showed that transients produce no vocalizations whatsoever apart from when they have made a kill or are participating in surface-active behaviors. What is the reasoning behind food-associated vocalizations? While we still are not sure, it is likely related to socialization. Transients frequently share prey amongst each other and high rates of vocalization after a kill may aid in doing so. 

References: 

Photo: Eva Saulitis (left) and NOAA Fisheries (right)

Deeke V., Ford JKB., and Slater P. 2005. The vocal behaviour of mammal-eating killer whales:
communicating with costly calls. Animal Behavior, 69: 395-405.

Northern sea otters (Enhydra lutris kenyoni) i…

Northern sea otters (Enhydra lutris kenyoni) in Seldovia, Alaska. 

Sea Otter Photo-Identification

Sea Otter Photo-Identification

You are probably familiar with the technique of photo-identification when it comes to whales and dolphins (if you are not, read more here!), but did you know the same principle applies to sea otters too?

Biologists can distinguish individual sea otters by photographing their noses. Each nose is shaped differently, and many otters have pink scar tissue. Scarring is especially prolific in females due to the mating bite that males inflict upon females during copulation. However, using photo-ID with sea otters can be difficult due to the fact nose scarring can change from year to year, sometimes resulting in misidentifications. 

The two photos above are of an elderly female otter that we have dubbed “Beatrice.” For the past two years, Beatrice has taken up semi-residence in the Homer Harbor in Homer, Alaska, where she takes advantage of easy meals in the form of crabs and blue mussels. Whenever I’d see an old female otter munching away in the harbor, I suspected I was seeing the same individual each time, but wasn’t able to confirm that until I compared some relatively good quality photos of her nose. In the year between these two photos, she did pick up some additional scarring, but overall her nose looks mostly the same. Hopefully Beatrice will still be there this summer for more comparisons!

Read more about sea otter photo-identification.

Whale Watching: Good or Bad?

Whale Watching: Good or Bad?

Whale watching is a worldwide industry worth more than $2 billion. Seeing a whale in the wild is a bucket list item for countless people all over the globe.

But are you actively harming whales when you go on a whale watching trip?

Whale watching is a hot topic, particularly in the debate over keeping cetaceans (whales, dolphins, and porpoises) in human care. Avid proponents of cetacean captivity often vilify the practice of whale watching, claiming it harms cetaceans and is unsustainable, while extreme anti-captivity activists typically paint whale watching as a harmless activity that does not impact wildlife. The reality is that the truth lies somewhere in between these two extreme views.

Whale watching is a multi-faceted issue that depends on many factors, such as region, species, and even the individual population. Whale watching can be done from boats, kayaks, paddle boards, and even while snorkeling or diving. Each type of whale watching has its benefits and its drawbacks. When is whale watching harmful, and when is it benign? Are there any benefits? Many biologists have attempted to answer these questions by doing studies on whale watching all around the world. Let’s examine this issue in more detail below.

Negative Aspects of Whale Watching

Though we might like to think that whales and dolphins enjoy being around us as much as we enjoy being around them, it’s usually not the case. Vessel traffic, including that from whale watching boats, can put stress on the animals. Here are some examples of when whale watching can have negative impacts on the animals:

  •  Minke whales in Iceland have been documented reacting to approaching whale watching as if they were predators, and whale watching in this region appears to disrupt normal feeding behavior. [X]
  • Hawaiian spinner dolphins rest during the day and are often disturbed during prime sleeping hours by dolphin watching vessels and snorkelers [X] 
  • Whale watching vessels in Panama directly killed at least 10 cetaceans in 2012 and 2013 [X]

These are just a few examples. Other studies document whale watching’s negative impacts on the the St. Lawrence belugas, killer whales in Norway, Irrawaddy dolphins, and bottlenose dolphins in New Zealand. Whale watching can change the activity budgets of animals, increase their respiration rates, cause avoidance behaviors, alter feeding patterns, and even change vocalizations. In more extreme cases, animals can be killed during whale watching trips by vessel strikes. 

Benefits of Whale Watching

Not all whale watching is doom and gloom, however. There are plenty of reputable companies and programs that responsibly view wild cetaceans, minimize their impact, and contribute to education, conservation, and meaningful research. When whale watching is conducted properly, there appears to be little impact on the animals.

One endangered population of killer whales, the southern resident killer whales, is subjected to high amounts of whale watching. Whale watching and its impacts on this imperiled population have been studied extensively and is greatly debated among whale advocates, whale watching companies, and scientists in this region. One particular study showed that whale watching does not actually have as much of an impact as other stressors, such as lack of prey. The biologists measured stress hormones in the whales and found that concentrations of stress hormones were lowest during the highest levels of vessel traffic, and this coincided with peak salmon availability [X]. This indicates when the whales have access to adequate prey, whale watching and other forms of vessel traffic do not have as much of a negative impact on them. That is not to say that whale watching doesn’t affect them at all: other studies have documented changes in behavior, but it’s likely not as negative as many people make it out to be. 

What benefits does whale watching provide? Eric Hoyt provides a list of benefits in his paper “Sustainable ecotourism on Atlantic islands, with special reference to whale watching, marine protected areas and sanctuaries for cetaceans”

  • Recreation
  • Scientific 
  • Education
  • Financial 
  • Cultural 
  • Heritage
  • Social 
  • Aesthetic 
  • Spiritual
  • Psychological 
  • Political 
  • Remote viewing
  • Environmental quality value 
  • Ecological function value

Choosing a Responsible Whale Watching Company

We now know that whale watching can be harmful if not done right. How can you choose a company that will respect the animals and minimize your impact? In some regions, there are special voluntary programs and organizations that companies can become part of that add an extra layer of protection to the animals being observed. 

In the United States, the NOAA sponsored program Whale SENSE provides extra training for whale watching companies to ensure they are conducting their whale watches in the safest and most responsible way possible. Whale SENSE certified companies can be found in Alaska and in New England. 

The Pacific Whale Watch Association is a group of whale watching companies in Washington State and British Columbia that have implemented even further regulations (more than what federal law requires) upon themselves in order to reduce their impact on the animals they view. 

So far, such programs are mainly restricted to the US and Canada. 

Conclusions

The pros and cons of whale watching are nicely summarized in the book “Ecotourism’s Promise and Peril: A Biological Evaluation” and the authors come to the conclusion that: 

“Marine mammals are charismatic animals, and many of them represent top predators and iconic species often referred to as keystone and umbrella species. They are keystone because their disappearance may lead to the loss of other species, and umbrella because conservation actions that mitigate threats to them are expected to improve the protection of other organisms and the ecosystem itself. In many areas around the world, the importance of these animals as keystone and umbrella species is being increasingly recognized and, consequently, so is the need to protect this captivating megafauna. Marine mammal-based tourism, if conducted properly and on a sustainable basis, is a “benign” industry. Ecotourism done right cannot only work, but it can work well. Marine mammals’ welfare should, however, remain the main objective of this industry because, without these animals, there will be no ecotourism at all.”

Harbor seals congregate to Fisherman’s Bend in…

Harbor seals congregate to Fisherman’s Bend in Juneau, Alaska for their morning yoga sessions. Perhaps this move is called “Sun Sealutations”? 😉

We love clear water conditions.

We love clear water conditions.

They are perfect for viewing dolphins out of the underwater viewing pods aboard Manute’a- and for the dolphins to look at you!

Photo by Naturalist Craig DeWitt | www.dolphinsafari.com 

A Mother’s Bond: “Mourning” Behavior in Killer…

A Mother’s Bond: “Mourning” Behavior in Killer Whales

Pictured above is female Alaskan resident killer whale AX76 and her presumed first calf. If it is a female, she will stick by AX76 for most of her life; she may eventually break off and form her own group when she begins have calves of her own, but will always be nearby her own mother. If it is a male, this little calf will never stray far from his mom, even when he is a fully grown bull. In short, the bonds between a mother killer whale and her offspring are some of the strongest in the animal kingdom. 

So what if the worst happens? What if this calf dies before it has a chance to grow up?

It is very difficult, if not impossible, to know what an animal thinks and feels. We must be careful when ascribing emotions to other species; sometimes we project our own human emotions onto animals even when it’s not necessarily accurate.

While we can never be absolutely sure what fellow pod members are feeling when a killer whale calf dies prematurely, there is definitely something going on. 

L72 Racer carrying her dead newborn. Photo by Robin Baird of Cascadia Research.

Epimeletic behavior refers to the behavior of an adult cetacean that is aiding a distressed, injured, or dead individual, sometimes carrying it around at the surface, protecting it, or attempting to save it in some way. This type of behavior is seen in several species of cetaceans, including killer whales. 

Often, the mother of a recently deceased calf is seen pushing the dead infant’s body around at the surface. This can last for hours or even days on end. Researchers believe in these cases, it is very likely that these are grief or mourning behaviors. Epimeletic behaviors may initially be the mother’s attempt to rescue her calf, (i.e holding it at the surface to breathe). However, even after the calf is long dead, mothers still stay with their babies. 

Grief behaviors do not appear to provide any benefit to the animal grieving; indeed, these behaviors likely have high costs to the individual. The strong social bonds that killer whales have to their offspring and relatives are probably the main causes for such behavior, which is notably lacking in other marine mammal species, such as pinnipeds. 

A female killer whale from New Zealand pushing her dead calf with her melon; this mother stayed with the calf for two days. Photo by Orca Research Trust. 

The grief a mother feels may continue long after the body of her dead infant is removed. While not a killer whale, there is one case of a captive beluga that showed us this mourning process. After a failed pregnancy, a dead calf was removed from the body of a female beluga and taken out of the pool. The mother, with no calf in sight, resorted to pushing around her own placenta. The placenta was eventually removed as well, and the grieving mother carried around a buoy for several months. 

It is hard to look at this types of behaviors and see anything but a grieving, mourning mother. We know from studies of their brain structure that killer whales are highly emotional creatures that likely experience a wide range of feelings. It is not such a stretch to say that they likely feel sorrow (or, perhaps something similar) when a family member dies. 

Sexual Dimorphism in Killer Whales: What’s the…

Sexual Dimorphism in Killer Whales: What’s the Purpose?

Sexual dimorphism refers to the differences in size and/or morphology between males and females in a species. This is seen in organisms across many different taxa. In cetaceans, the most obvious example of extreme sexual dimorphism is in killer whales. 

Depending on the population, male killer whales reach lengths of 20-26 feet and generally weigh between 8,000-12,000 pounds. Females, on the other hand, are much smaller, being only 16-23 feet in length and weighing around 3,000 to 6,000 pounds. Adult males are readily distinguishable by their tall, straight dorsal fins; some fins can reach up to 6 feet in height!. The dorsal fins on females are much smaller and falcate, generally not exceeding 3-4 feet. Another size difference between the sexes is in the pectoral flippers: males have large paddle shaped flippers that can be 6 feet long and 3 feet across. Females have much smaller flippers. 

So what’s the point of these exaggerated size differences? 

The paper “Sexual segregation when foraging in an extremely social killer whale population” by Beerman et al. presents an interesting idea. The authors conducted a 12 year study investigating the differences in foraging behavior between female and male northern resident killer whales. Resident killer whales are highly social and display remarkable maternal fidelity. Previous research hypothesized that in order to reduce intraspecific prey competition within family groups, female killer whales would prefer shallow areas for foraging while males would prefer deeper waters.

Beerman et al. put this hypothesis to the test. They found that, as predicted, females foraged preferentially in shallow areas close to shore. However, contrary to the hypothesis, males did not show a preference for deep water. In fact, they didn’t really show a preference for any depth and tended to forage all over the place, including shallow waters. This contradicts the idea that males are avoiding shallower areas to leave prey for females and calves. 

An alternative hypothesis the authors propose is that the physiological differences of male killer whales (i.e larger body size) allows them to forage in a range of depths as opposed to females, who may be constricted to shallower areas. It has been well-established that larger males are capable of deeper and longer dives than females. This study shows that kin selection is likely not the sole driver of differences in foraging habitats between male and female killer whales. While competition for prey between the group is certainly reduced by this habitat partitioning, it is possible that it is simply a side effect of physiological constraints.

It is possible that larger body size is being selected for in male killer whales in order exploit a larger range of foraging habitats. This may explain the extreme size difference we see in male and female killer whales, at least in resident killer whales. Of course, this is just one study done on one population, so we can’t conclude this is true for the species as a whole. However, if this physiological hypothesis is true, it should also apply to other killer whales populations around the world. More research is needed, but this study provides an important clue in investigating killer whale sexual dimorphism!

Fast Facts About Alaska’s Resident Killer Whal…

Fast Facts About Alaska’s Resident Killer Whales

  • The minimum population estimate for the Alaska resident stock is 2,084. [X]
  • There are likely 2 resident populations in Alaska: the southern Alaska residents, ranging from southeast Alaska to Kodiak Island, and still relatively unstudied population found in western Alaska. [X]
  • In southern Alaska, their main prey source is silver salmon and king salmon, while in western Alaska, preliminary studies suggest other species such as Atka mackerel may be important prey items. [X]
  • The three pods seen in southeast Alaska (AF5, AF22, and AG) have been documented in Kachemak Bay, 621 miles away from their home range. [X]
  • There is evidence to suggest Alaskan residents have higher life expectancies than Alaskan transient killer whales occupying the same region. [X]
  • The southern Alaska resident population contains two killer whale haplotypes: the southern resident (SR) haplotype and northern resident (NR) haplotype. [X]
  • Female southern Alaska resident killer whales have an average life expectancy of 39.4 years and for males, 31.4 years. Maximum longevities are 60-70 years and 50-60 years for females and males, respectively. [X]