COSEWIC Recommends an Endangered Listing for Canada’s Eastern Pacific Grey Whales

On Dec 4, 2017, COSEWIC (Committee on the Status of Endangered Wildlife in Canada) announced recommendations for changes to listings of 44 wildlife species under the Species at Risk Act (SARA). This non-governmental committee of scientists assesses and designates the conservation status of species in Canada.  COSEWIC has recommended an endangered listing for two of the three populations of Pacific grey whale (Eschrichtius robustus) that use Canadian waters.

Grey whales are found only in the North Pacific Ocean. A population of grey whales once existed in the North Atlantic as well, but they were extirpated by hunting by the 17^th century¹.  This species is strongly migratory, traveling more 15,000 km from southern breeding grounds to northern feeding grounds annually¹.  Newborn calves follow their mothers to foraging areas, and return faithfully each year to their mother’s migratory destination².

Grey whales are divided into two populations: the Eastern Pacific Population, which overwinter in Mexico and travel up the west coast of North America to feeding grounds in the north, and the Western Pacific Population, which occur along the east coast of Asia. The Western Pacific Population is listed at ‘Critically Endangered’ by the IUCN (International Union for Conservation of Nature), and comprises less than 150 animals¹.  The Eastern Pacific Population, which numbers approximately 20,000 individuals, is currently listed as ‘Least Concern’ by the IUCN and has been designated as ‘Special Concern’ under Canada’s Species at Risk Act¹.

The Eastern Pacific Population has been further divided into three distinct groups. All three groups winter in Mexican waters and migrate up the Canadian coast to feed in different regions.  The largest population, which forage in Alaska, was assessed by COSEWIC as ‘Not at Risk’.  The two other groups-a remnant population that summers along the Russian coast, and a small group that feeds in scattered locations throughout BC and California-were both assessed as ‘Endangered’.

The small population that is found in BC waters during the summer and fall is comprised of approximately 100 individuals, and is known as the “Pacific Coast Feeding Aggregation”. These animals do not migrate to feeding grounds in Alaska, and instead forage in scattered locations from Central California to Kodiak Island, AK.  Scientists have determined that these animals are genetically differentiated from the Alaskan population, and therefore warrant separate management for conservation³.

Another small remnant population can be found summering in the waters around Sakhalin and Kamchatcka in Russia⁴.  Until recently, these animals were thought to be members of the Western Pacific Population, but their winter range had not been determined.  In 2011, researchers from Oregon State University attempted to solve this mystery by attaching satellite-monitoring tags to seven grey whales in these Russian feeding grounds.  The results were surprising; rather than migrating south towards Japan, three individuals began migrating eastward towards the Bering Sea².  Two of the tags transmitted long enough to reveal their migratory patterns.  One male, named “Flex”, reached the Oregon coast before his tag stopped transmitting.  Another tag, placed on a female called “Varvara”, travelled from Russia to breeding lagoons in the Baja, and then travelled back to Russia the following summer-a round trip of over 22,511 kilometres!  Recent studies provide evidence that animals that follow this migration route are genetically distinct from other members of the Eastern Pacific Population, and should be managed as a separate unit under Canada’s Species at Risk Act^4,5.

Routes of three western grey whales instrumented with satellite monitoring tags off Sakhalin Island, Russia. (Mate et al., 2015)

Although the Eastern Pacific grey whale population has recovered overall from 19^th century whaling, it is threatened by increasing development and human activity in Mexican breeding lagoons¹.  Additionally, Grey whales are susceptible to vessel strikes⁶, acoustic disturbance from shipping, changes in ice cover at Arctic feeding grounds, disruption of benthic feeding habitat, and entanglement in fishing gear and other marine debris¹.  Mortalities due to exposure to these threats could lead to a loss of genetic diversity for the two small, genetically isolated sub-populations of grey whales that utilize BC’s waters, warranting COSEWIC’s recommendation of an endangered listing for these groups.

You can help protect grey whales in BC waters! Report your grey whale sightings to the BC Cetacean Sightings Network to help inform researchers of the relative abundance, distribution, and habitat use of these animals.  Follow the Be Whale Wise Guidelines while on the water to decrease the chance of vessel strike.  Grey whales travel close to shore during their northward migrations, and following the Whale Trail is an excellent way to view these magnificent animals from land without causing vessel disturbance.  If you are a commercial mariner, refer to our Mariners Guide to Whales, Dolphins, and Porpoises of Western Canada to learn more about how you can reduce the impact of your vessel.  Help remove marine debris by participating in a shoreline cleanup, and report any incidences of grey whale entanglement to the Marine Mammal Incident Reporting Hotline at 1-800-465-4336.

References

1. Fisheries and Oceans Canada. (2010). Management Plan for the Grey Whale (Eschrichtius robustus) in Canada [Final]. Species at Risk Act Management Plan Series. Fisheries and Oceans Canada, Ottawa.
2. Mate, B.R., Ilyashenko, V.Y., Bradford, A.L. Vertyankin, V.V., Tsidulko, G.A., Rozhnov, V.V., & Irvine, L.M. (2015). Critically endangered western grey whales migrate to the eastern North Pacific. Biology Letters 11, 4.
3. Frasier, T.R., Koroscil, S.M., White, B.N., and Darling, J.D. (2011). Assessment of population substructure in relation to summer feeding round use in the eastern Norther Pacific grey whale. Endangered Species Research 14.
4. Cooke, J.G., Weller, D.W., Bradford, A.L., Sychenko, O., Burdin, A.M., Lang, A.R., & Bronwell R.L. (2017). Population assessment update for Sakhalin gray whales, with reference to stock identity. Western Grey Whale Advistory Panel, International Whaling Commission. 9pp.
5. Cooke, J.G., Weller, D.W., Bradford, A.L., Sychenko, O., Burdin, A.M., & Brownell, R.L. Population Assessment of the Sakhalin gray whale aggregation. (2016). Paper SC/A16/GW2 presented to IWC Workshop.
6. Ford, J.K.B., Durban, J.W., Ellis, G.M., Towers, J.R., Pilkington, J.R., Barrett-Lennard, L.G., & Andrews, R.D. (2013). New insights into the northward migration route of gray whales between Vancouver Island, British Columbia, and southeastern Alaska. Marine Mammal Science, 29 (2).