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At Risk Whales, Dolphins, and Porpoises
Porpoises, whales, and dolphins make up a group called cetaceans. Despite having fish-like features, these animals are actually mammals. They give birth to live young, produce milk, and have hair, just like us! Unfortunately, the cetaceans in the Salish Sea are facing many threats, and there are a number of species on the at-risk watch list. Four cetaceans at risk in the Salish Sea include: The Grey Whale (Eschrichtius robustus), the Humpback Whale (Megaptera novaeangliae), the Harbour Porpoise (Phocoena phocoena), and the Killer Whale (Orcinus orca).
Odontoceti or Mysticeti?
Our Salish Sea cetaceans (and cetaceans around the world) can be divided into two general groups, odontocetes and mysticetes. Odontocetes are also referred to as toothed whales, and, as whales evolved from toothed, even-toed ungulates (hooved animals), odontocetes are considered to be their primitive form. In contrast, mysticetes are equipped with baleen, a filter feeding system composed of a keratinized structure (the proteins that make up our hair and nails) in the place of teeth. Baleen represents what is known as a ‘novel adaptation’, or ‘key innovation’ as, by evolving baleen, mysticetes were able to access smaller prey, which were in much higher abundance than any prey that toothed whales could capture. In ecology, access to more prey means access to more energy, and more energy means a better chance of successful reproduction. So, by evolving baleen, mysticetes became extremely ecologically successful, and populations expanded rapidly to fill the worlds oceans. Mysticetes have several different approaches to feeding, including lunging, skimming, and suction.
Grey Whale (Eschrichtius robustus)
Grey whales are solitary, 11-14 meters long, and have no dorsal fin (only a series of bony vertebrae “knuckles” near the tail). They are baleen whales (mysticetes) that use suction to take big gulps of water before they push it back out through their baleen. What is left in their mouths are the small marine organisms that they consume as prey. Unlike most baleen whales, grey whales feed on the ocean floor. They strain out small invertebrates from the soft sediment, leaving large, mouth-sized impressions on the ocean floor. During the spring and summer months, grey whales will also feed on herring eggs and larvae in eelgrass beds.
Intensive commercial whaling throughout the 20th century resulted in dramatic declines in grey whale abundance. The current status of grey whales varies greatly by population. In Canadian coastal waters, most grey whales are members of the Eastern North Pacific population, which can be further split into two separate units, the Northern Pacific Migratory population, and the Pacific Coast Feeding Aggregation subpopulation. The former, which migrates from winter calving grounds in Mexico to the Bering, Chukchi, and Beaufort Seas, has recovered well, and now sits at 20,000 individuals. Although this population is considered relatively stable, between 1998 and 2002 nearly 1/3 of the population was lost due to suspected poor summer feeding conditions. Therefore, this population remains listed as of ‘special concern’ by both The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and the Species at Risk Act (SARA). Similarly, the Pacific Coast Feeding Aggregation migrates northward from calving grounds in Mexico, however, they do not venture as far north. Instead, they spend their summer and fall seasons scattered across various feeding locations between the coastal waters of California and Alaska. This subpopulation is made up of only a few hundred whales, and is not surprisingly listed as endangered.
On the other side of the Pacific Ocean we have the Western North Pacific population. This population is often referred to as the Asian grey whale, as the majority historically migrated from summer feeding grounds off the northeastern Sakhalin coast to wintering grounds in southeastern China. However, recent research through satellite tagging has shown that this migration path is not always followed, and that the Eastern and Western North Pacific Grey Whales may exchange individuals at a low rate. Key to making well-informed conservation decisions is gaining a better understanding of the connection between these two populations. Western North Pacific Grey Whales are currently listed as endangered, with only around 200 members.
Humpback Whale (Megaptera novaeangliae)
This large, up to 17m long whale is loosely social, travelling in large groups for no longer than a few days at a time. Like grey whales, humpbacks are baleen whales (mysticetes). The two may often be confused, however humpback whales can be identified by their extremely long flippers, serrated flukes (tail fin), and knob-like tubercles on their head, jaws, and flippers. Additionally, in contrast to grey whales, humpbacks have a lunge approach to feeding. They surface quickly with their mouths open, capturing their prey in the water column. As they reach the surface, it is hard to not notice the large slits (pleats) running from their chin to their navel area. These expand to incorporate massive gulps of their prey; typically krill or small schooling fish. Humpbacks migrate from their breeding grounds in lower latitude areas in the winter, to their summer feeding grounds in high latitude areas. They display a high degree of site fidelity, meaning they almost always return to the same feeding location each year. The humpbacks off the west coast of British Columbia typically migrate from breeding grounds in Hawaii, Mexico, and Central America, and are members of the North Pacific population. They were severely impacted by whaling in the 20th century, with numbers decreasing to only 6000 individual whales. Luckily, there has been recovery since then, and the current population count is 18,302 whales, increasing by roughly 4% annually. Their growing population count sparked their down listing from threatened to ‘species of special concern’ in 2011 by COSEWIC (Committee on the Status of Endangered Wildlife in Canada).
Harbour Porpoise (Phocoena phocoena)
Harbour porpoises can range up to 2 m in length, therefore making them the smallest cetacean in British Columbia. They are toothed whales (odontocetes) that feed on a variety of prey, including fishes such as herring, walleye pollock, and eulachon. They have also been known to feed on squid. Harbour porpoises typically travel in groups of 2 to 5 individuals, but may aggregate in larger groups when prey is abundant. Identification of Harbour Porpoises is fairly easy, however, their small dorsal fin and discrete emerging behaviour makes spotting them challenge. In British Columbia, harbour porpoises are most likely to be found in shallow waters (<150 m depth) where prey density is typically highest. Because of their non-migratory nature, they are constantly exposed to a number of human related threats such as ocean noise, entanglement in fishing gear, ship strikes, and coastal development. Harbour porpoises are currently listed as a species of special concern by COSEWIC.
Killer Whales (Orcinus orca)
For information on the second most widespread mammal on earth, and on the Galiano Conservancy’s Cetacean Conservation Project visit our “Orcas” page, here.
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As the Salish Sea is bordered by a region of high human population density, cetaceans are exposed to number of human impacts. One of the most well understood is the high degree of vessel traffic, which on its own poses a multitude of threats. Between 2004 and 2011 thirty vessel strikes were reported to the BC Cetacean Sightings Network, with many more going unreported, or unnoticed. Additionally, even the presence of vessels nearby is known to have behavioural implications for cetaceans. Several studies have shown that some whales may spend less time foraging, and more time evading traffic, while others will display more energy intensive behaviours, such as breaching or slapping their flukes in presence of vessels. Furthermore, vessels create acoustic disturbances that may interfere with cetacean echolocation (clicks, whistles, and pulsed sounds) that is used to communicate with one another, locate prey, and navigate. When vessel noise interferes with whale calls, it is referred to as ‘masking’, and as a response to masking, some whales have been known to raise the amplitude of their calls, potentially increasing energy expenditure. In either case of acoustic or physical disturbance, if the impacted whales are already suffering from prey-scarcity, disturbance could have dire implications. Lastly, vessels also emit toxins into ocean water. Cetaceans are extremely vulnerable to toxins as they do not have sinuses to filter out the pollutants, nor sense of smell to avoid them.
Learn more about cetaceans and boating here.
As the human population on earth grows, so does our food industry! But this is bad news for cetaceans. Unfortunately, human fisheries often target important prey species in Cetacean diets. For cetaceans that are specialists (eating only one source of food) this can become highly problematic. For example, the Southern Resident Killer Whales (SRKW) are salmon specialists, with about 80% of their diets being made up of Chinook salmon in particular. However, humans also have high interest in Chinook salmon, and in recent years human overfishing has caused Chinook stocks to plummet, leaving SRKW in a state of prey scarcity. In contrast, cetaceans with varied sources of prey in their diets can often change focal food sources when scarcity arises. Additionally, the ‘gillnets’ and ‘seine nets’ used by fisheries may result in cetaceans becoming entangled or caught as bi-catch. Around 86% of the world’s toothed whales are now threatened by the world’s fisheries, and 300,000 Cetaceans die annually from entanglement. Half of all humpbacks will be caught in fishing gear at least once in their life.
Persistent organic pollutants (POPs) are the most notable class of contaminants threatening Cetaceans. They are used in products such as flame retardants, electronics, transfer fluids, and pesticide manufacturing. Often referred to as the ‘forever chemicals’, POPs are highly resistant to environmental degradation, and thus, POPs can be found in a number of marine organisms, big and small. However, they become most problematic in larger organisms due to the processes of bioaccumulation and biomagnification. Bioaccumulation refers to an individual organism’s gradual accumulation of contaminants throughout its lifespan, whereas biomagnification refers to the disproportionately higher level of contaminants that predators build up as they ingest all other contaminated organisms in the food chain.
In a 2019 study, biologists tested the levels of POPs in blue whales (baleen whales/mysticetes) in the Southern Hemisphere. Their study demonstrated that POPs are measurable in high numbers in Blue Whales, however concentrations were notably higher in males, than females. As POPs are lipophilic (stored in fatty tissues), females are able to unload significant portions of contaminants to their offspring through breastfeeding. Unfortunately this only contributes to a much higher contaminant load in offspring, which could eventually be passed down again, depending on the animals sex. Another study on sea lions, relatives of Cetaceans, found that, when exposed to POPs, sea lions had lowered immune function, lowered reproduction, and changes in hormone levels.
Like so many other animals around the globe, cetaceans are extremely vulnerable to climate change. For some cetaceans the impacts may be more severe than for others. For example, for specialized species such as the southern resident killer whales, the impacts could be severe as prey switching is often unfeasible. Chinook salmon, the southern resident killer whales preferred prey, is already under severe stress, but climate change adds another set of challenges. Studies have shown that rising stream temperatures caused by climate change can have severe implications for salmon survival rates. Salmon may also be subject to freshwater acidification, which may hinder growth and survival of fish in developmental life stages. Climate change may also provide conditions that enable better survival of invasive species. In turn, this may cause shifts in predation of salmon, or changes in prey availability that influence survival rates.
For cetaceans in general, the impacts of climate change are expected to exacerbate already existing threats, such as habitat loss, pollution, and disease. In the arctic, many cetaceans (including our grey whales) rely on zooplankton that are intricately tied with sea ice conditions. Changing sea ice cover thus presents potential challenges for feeding.
The good news is that there is hope for our cetaceans. Our understanding of whale ecology and biology has vastly improved in recent years, and with this knowledge we have become better equipped to assess and mitigate the risks our behaviours pose. For example, long term studies of Southern Resident Killer Whales have enabled researchers to discover and map regions of critical habitat. In turn, this has led to a number of vessel exclusion and fishing exclusion zone designations. In May 2020, Canada’s Department of Fisheries and Oceans also implemented new mandatory and voluntary protection measures for Southern Resident Killer Whales, including a 400m vessel approach limit in Southern BC coastal waters.
There is still knowledge to be gained, and conservation work to be done, but in the mean time one of the most powerful conservation tools we can use is education. If the public is informed of the risks cetaceans face, we have a better means of ensuring their prosperous future in the Salish Sea. This is precisely the goal of the Galiano Conservancy.
We could not make this Cetacean Project happen without support from both Canada’s Department of Fisheries and Oceans and our community! Consider helping us continue this work by making a donation to the Conservancy today, or email email@example.com for information on volunteer opportunities with us and our partners!
References and Further Reading