Eschrichtius robustus (western subpopulation)


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Eschrichtius robustus (western subpopulation)
Species Authority: (Lilljeborg, 1861)
Parent Species:
Common Name/s:
English Gray Whale, Grey Whale
Taxonomic Notes:

This subpopulation of Eschrichtius robustus (Lilljeborg, 1861), called the western gray whale, is probably genetically isolated from the only other extant subpopulation, known as the eastern gray whale (LeDuc et al. 2002); the ranges do not appear to overlap (Blokhin 1996). It is listed separately for conservation and management purposes (see separate listing for the global species).

Assessment Information [top]

Red List Category & Criteria: Critically Endangered C2a(ii); E ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor/s: Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N.
Reviewer/s: Taylor, B.L. & Notarbartolo di Sciara, G. (Cetacean Red List Authority)
Results of a quantitative population analysis (Cooke et al. 2006) indicate Critically Endangered under the assumption that recent mortality levels continue, based on an extinction probability exceeding 50% within three generations (criterion E), or a projected continuing decline of the subpopulation in combination with a mature population size less than 250 (criterion C2a(ii)). In addition, the small absolute subpopulation size, and the estimate of at most 35 reproductive females means that the subpopulation would easily qualify as Endangered under criterion D (< 250 mature individuals).
2000 Critically Endangered
1996 Endangered

Geographic Range [top]

Range Description:

The western gray whale summers in the Okhotsk Sea, mainly off the northeastern coast of Sakhalin Island (Russian Federation). There are also occasional sightings off the eastern coast of Kamchatka (Russian Federation) and in other coastal waters of the northern Okhotsk Sea (Vladimirov 1994, Weller et al. 1999). Its migration routes and wintering grounds are poorly known, the only recent information being from occasional records on both the eastern and western coasts of Japan (Kato et al. 2006) and along the Chinese coast (Zhu and Yue 1998). Until 1966, there was a whaling ground off Ulsan (southeastern Korea Peninsula), where whales were taken during November to April, with two peaks (in December/January and March/April), suggestive of south- and northbound migrations respectively through the Sea of Japan (Kato and Kasuya 2002). However, no gray whales have been recorded in the Korean whaling grounds since 1968. The great majority of recent Japanese records are on the Pacific side, suggesting that this is now the more important migration route. The few modern records from China are scattered along virtually the entire Chinese coast from the northern Yellow Sea to the Hainan Strait in the south (Zhu and Yue 1998). The calving grounds are unknown but may be around Hainan Island, this being the southwestern end of the known range (Brownell and Chun 1977).

China; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Russian Federation
FAO Marine Fishing Areas:
Pacific – northwest
Range Map: Click here to open the map viewer and explore range.

Population [top]


Western gray whales were thought to be extinct as recently as 1972 (Bowen 1974), but a small number are now known to survive (Berzin 1974, Weller et al. 2002); the best estimate for 2006 is 113-131 animals, of which 26-35 are reproductive females, based on an analysis of photo-identification data (Cooke et al. 2006). The figures include adjustments for the photo-identified whales that are likely to have died and for the estimated number of living whales that have yet to be catalogued. In the absence of additional new mortality in excess of the estimated rate over 1994-2004, the population size is projected to increase at 2-4% per annum (Cooke et al. 2006). However, even a very small number of additional annual female deaths will cause the subpopulation to decline.

Population Trend: Increasing

Habitat and Ecology [top]

Habitat and Ecology:

The main feeding habitat of this subpopulation is the shallow (5-15 m depth) shelf of northeastern SakhalinIsland, particularly off the southern portion of Piltun Lagoon, where the main prey species appear to be amphipods and isopods (Weller et al., 1999).  In some years the whales have also used an offshore feeding ground in 30-35m depth southeast of ChayvoBay where benthic amphipods and cumaceans are the main prey species (Fadeev 2003). Some gray whales have also been seen off western Kamchatka but to date all whales photographed there are also known from the Piltun area (Reeves et al. 2005). Recently whales have also been seen, apparently feeding, in SevernayaBay on the north coast of Sakhalin (IUCN 2006). 

Systems: Marine

Threats [top]

Major Threat(s):

Western gray whales were hunted by aboriginal people in the northern part of their range since prehistoric times but to an unknown extent (Mitchell, 1979). They were taken by Japanese hand-harpoon whalers in the Sea of Japan since at least the 16th century, and by net whalers on the Pacific coast in the 17th to 19th century (Omura 1984, 1988).  Western gray whales were also taken by European and American whalers, mainly in the Okhotsk Sea, from the late 1840s to perhaps the start of the 20th century (Henderson 1984), and by Russian steam whalers on the Russian far eastern coast at the end of the 19th century (Andrews 1914, Weller et al. 2002). Quantitative information is scarce, but it is possible that the subpopulation was already depleted by the start of modern whaling at the end of the 19th century. During 1890-1966 an estimated 1,800 – 2,000 gray whales were taken off the Korea peninsula and Japan (Kato and Kasuya 2002). Apart from the main grounds off southeastern Korea, whales were also taken in the Yellow Sea in the early part of this period. Occasional catches are recorded from China during 1916-58 (Zhu and Yue 1998). It is not known whether any whales have been taken by the Democratic People’s Republic of Korea.


Three western gray whales, all females, were fatally entangled in net-traps on the Pacific coast of Japan in 2005 (Kato et al., 2006). Subpopulation projections show that if this level of mortality continues, the subpopulation would decline towards extinction (Cooke et al. 2006, IWC 2007). Most recently, a female yearling (9.1 m) was killed in Yoshihama Bay, Sanriku, Japan on 19 January 2007. The stranding of a dead western gray whale in Japan with a hand harpoon lodged in it of the kind used by porpoise hunters (Brownell and Kasuya 1999) is of concern, as is the finding of gray whale meat on domestic whale meat markets on the Pacific coast of Japan (Baker et al. 2002). Incidental catches of cetaceans in the extensive coastal net fisheries off southern China are also of concern (Zhou and Wang 1994).


The substantial nearshore industrialization and shipping congestion throughout the migratory corridors of this subpopulation represent potential threats by increasing the likelihood of exposure to ship strikes, chemical pollution, and general disturbance (Weller et al. 2002).


Offshore gas and oil development in the Okhotsk Sea within 20 km of the primary feeding ground off northeast Sakhalin Island in the Okhotsk Sea is of particular concern. Activities related to oil and gas exploration, including geophysical seismic surveying, pipelaying and drilling operations, increased vessel traffic, and oil spills, all pose potential threats to western gray whales. Disturbance from underwater industrial noise may displace whales from critical feeding habitat. Physical habitat damage from drilling and dredging operations, combined with possible impacts of oil and chemical spills on benthic prey communities also warrants concern (Reeves et al. 2005)

Conservation Actions [top]

Conservation Actions:

International Whaling Commission (IWC) regulations protect western gray whales from commercial and aboriginal subsistence whaling; the range states of the Russian Federation, Japan, the Republic of Korea, and China, are members of the IWC (but as noted above, some limited illegal hunting may continue). Oil and gas companies operating off Sakhalin Island have implemented some voluntary measures to reduce their impacts on gray whales, such as speed restrictions on their vessels (Anon. 2006). At present, one oil company is co-operating with the IUCN Western Gray Whale Advisory Panel (WGWAP) although it is not bound by the panel’s recommendations (

Bibliography [top]

Andrews, R.C. 1914. Monographs of the Pacific Cetacea. I. The California gray whale (Rhachianectes glaucus Cope). Memoirs of the American Museum of Natural History New Series 1(5): 227-287.

Anonymous. 1999. Report of a review by an international group of scientists to consider the status of western gray whales, human-related threats to the population, and research and monitoring needs. 27-28 February 1999 workshop proceedings, National Marine Fisheries Service, Southwest Fisheries Science Center, La Jolla, CA. U.S.A.

Baillie, J. and Groombridge, B. 1996. 1996 IUCN Red List of Threatened Animals. International Union for Conservation of Nature, Gland, Switzerland.

Baker, C.S., Dalebout, M.L., Lento, G.M. and Funahashi, N. 2002. Gray Whale products sold in commercial markets along the Pacific coast of Japan. Marine Mammal Science 18: 295–300.

Barlow, J. and Clapham, P.J. 1997. A new birth-interval approach to estimating demographic parameters of humpback whales. Ecology 78(2): 535-546.

Berzin, A.A. 1974. Problems of studying whales (Cetacea). In: Zoology of Vertebrates, pp.158-189. Results of Science and Technology. Volume 6. VINITI Academy of Sciences, U.S.S.R.

Berzin, A.A. In press. Gray whales (Eschrichtius robustus) of the Okhotsk-Korean population in the Sea of Okhotsk. Journal of Cetacean Research Management Special Issue 3.

Berzin, A.A., Vladimirov, V.L. and Doroshenko, N.V. 1988. Results of aerial surveys to study the distribution and abundance of cetaceans in the coastal waters of the Sea of Okhotsk in 1986-1987. In: N.S. Chernysheva (ed.) Nauchno-issledovatel’skie ra’oty po morskim mlekopitayushchim severnoi chasti Tikhogo okeana v 1986-1987, pp.18-25. All-Union Scientific Research Institute of Fisheries and Oceanography (VNIRO), Moscow (in Russian).

Berzin, A.A., Vladimirov, V.L. and Doroshenko, N.V. 1990. Aerial surveys to determine the distribution and number of polar gray whales and beluga whales in the Sea of Okhotsk in 1985-1989. Izvestiya Tikhookeanskogo Nauchno-Issledovatel’skogo Instituta Rybnogo Khozyaistva I Okeanografii (TINRO) 112:51-60 (in Russian).

Berzin, A.A., Vladimirov, V.L. and Doroshenko, N.V. 1991. Results of aerial surveys to study the distribution and abundance of whales in the Sea of Okhotsk in 1988-1990. In: L.A. Popov (ed.) Nauchno-issledovatel’skie ra’oty po morskim mlekopitayushchim severnoi chasti Tikhogo okeana v 1989-1990, pp.6-17. All-Union Scientific Research Institute of Fisheries and Oceanography (VNIRO), Moscow (in Russian).

Blokhin, S.A. 1996. Distribution, abundance and behavior of gray whales (Eschrichtius robustus) of American and Asian populations in regions of their summer location nearshore of the Far East. Izvestiya Tikhookeanskogo Nauchno-Issledovatel’skogo Rybokhozyaistvennogo Tsentra 121:36-53. (in Russian).

Blokhin, S.A., Maminov, M.K. and Kosygin, G.M. 1985. On the Korean-Okhotsk population of gray whales. Report of the International Whaling Commission 35:375-376.

Bowen, S.L. 1974. Probable extinction of the Korean stock of the gray whale (Eschrichtius robustus). Journal of Mammalogy 55: 208-209.

Brownell Jr., R.L. 1999. Okhotsk gray whales: one of the most endangered whale populations. Sphere Square 13:2-3. CETUS Newsletter, Tokyo, Japan (in Japanese).

Brownell Jr., R.L. and Chun, C. 1977. Probable existence of the Korean stock of gray whales (Eschrichtius robustus). Journal of Mammalogy 58:237-239.

Brownell Jr., R.L. and Kasuya, T. 1999. Western gray whale captured off western Hokaido, Japan. Unpublished document, SC/51/AS25, submitted to the Scientific Committee of the International Whaling Commission.

Brownell Jr., R.L., Blokhin, S.A., Burdin, A.M., Berzin, A.A., LeDuc, R.G., Pitman, R.L. and Minakuchi, H. 1997. Observations on Okhotsk-Korean gray whales on their feeding grounds off Sakhalin Island. Report of the International Whaling Commission 47: 161-162.

Brown, M.W., Kraus, S.D., Gaskin, D.E. and White, B.N. 1994. Sexual composition and analysis of reproductive females in the North Atlantic right whale, Eubalaena glacialis, population. Marine Mammal Science 10: 253-265.

Bryant, P.J., Lafferty, C.M. and Lafferty, S.K. 1984. Reoccupation of Laguna Guerrero Negro, Baja California, Mexico, by gray whales. In: M.L. Jones, S.L. Swartz and S. Leatherwood (eds) The Gray Whale Eschrichtius robustus, pp.375-387. Academic Press, Orlando, FL.

Cooke, J.G., Weller, D.W., Bradford, A.L., Burdin, A.M. and Brownell Jr., R.L. 2006. Population assessment of western gray whales in 2006. Paper SC/58/BRG30 presented to the Inernational Whaling Commission Scientific Committee, June 2006.

Fadeev V.I. 2003. Benthos and prey studies in feeding grounds of the Okhotsk-Korean population of gray whales. Final report on materials from field studies on the research vessel Nevelskoy in 2002. Marine Biology Institute, Vladivostok.

Henderson, D. 1990. Gray whales and whalers on the China coast in 1869. Whalewatcher 24: 14-16.

Henderson, D.A. 1972. Men and whales at Scammon’s Lagoon. Dawson’s Book Shop, Los Angeles, CA.

Henderson, D.A. 1984. Nineteenth Century gray whaling: Grounds, catches, and kills, practices and depletion of the whale population. In: M.L. Jones, S.L. Swartz and S. Leatherwood (eds) The gray whale Eschrichtius robustus, pp.159-186. Academic Press, Orlando, FL.

Hilton-Taylor, C. 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK.

International Whaling Commission. 2007. Report of the Scientific Committee. Journal of Cetacean Research Management (Supplement) 9(2): iii-xi.

IUCN. 2006. Report of the 1st Meeting of the Western Gray Whale Advisory Panel. Prangins, Switzerland, November 2006. Available at:

IUCN. 2008. 2008 IUCN Red List of Threatened Species. Available at: (Accessed: 5 October 2008).

Kato, H. and Kasuya, T. 2002. Some analyses of the modern whaling catch history of the western North Pacific stock of gray whales (Eschrichtius robustus), with special reference to the Ulsan whaling ground. Journal of Cetacean Research Management 4(3): 277-282.

Kato, H. and Kasuya, T. In press. Catch history of the Asian stock of gray whales by modern whaling with some notes of migrations. Journal of Cetacean Research Management. Special Issue 3.

Kato, H. and Tokuhiro, Y. 1997. A sighting of gray whales off Kochi, southwest Japan in July 1997, with some notes on its possible migration in adjacent waters of Japan. Unpublished document, SC/49/AS17, submitted to the Scientific Committee of the International Whaling Commission.

Kato, H., Ishikawa, H., Bando, T., Mogoe, T. and Moronuki, H. 2006. Status Report of Conservation and Researches on the Western Gray Whales in Japan, June 2005 – May 2006. Paper SC/58/O14 presented to the IWC Scientific Committee, June 2006

Kim, S.L. and Oliver, J.S. 1989. Swarming benthic crustaceans in the Bering and Chukchi seas and their relation to geographic patterns in gray whale feeding. Canadian Journal of Zoology 67:1531-1542.

LeDuc, R.G., Weller, D.W., Hyde, J., Burdin, A.M., Rosel, P.E., Brownell, R.L., Würsig, B. and Dizon, A.E. 2002. Genetic differences between western and eastern gray whales (Eschrichtius robustus). Journal of Cetacean Research Management 4(1): 1-5.

Mitchell, E. 1979. Comments on the magnitude of the early catch of east Pacific gray whale (Eschrichtius robustus). Report of the International Whaling Commission. 29: 307-314.

Nerini, M. 1984. A review of gray whale feeding ecology. In: M.L. Jones, S.L. Swartz and S. Leatherwood (eds) The gray whale Eschrichtius robustus, pp.423-50. Academic Press, San Diego, CA.

Oliver, J.S., Slattery, P.N., Silberstein, M.A. and O’Connor, E.F. 1984. Gray whale feeding on dense ampeliscid amphipod communities near Bamfield, British Columbia. Canadian Journal of Zoology 62:41-49.

Omura, H. 1974. Possible migration route of the gray whale on the coast of Japan. Scientific Reports of the Whales Research Institute 26:1-14.

Omura, H. 1984. History of gray whales in Japan. In: M.L. Jones, S.L. Swartz, and S. Leatherwood (eds) The gray whale Eschrichtius robustus, pp.57-77. Academic Press, San Diego, CA.

Omura, H. 1988. Distribution and migration of the western Pacific stock of the gray whale. Scientific Reports of the Whales Research Institute 39:1-9.

Reeves, R.R., Brownell Jr., R.L., Burdin, A., Cooke, J.G., Darling, J.D., Donovan, G.P., Gulland, F.M.D., Moore, S.E., Nowacek, D.P., Ragen, T.J., Steiner, R.G., Van Blaricom, G.R., Vedenev, A. and Yablokov, A.V. 2005. Report of the Independent Scientific review Panel on the Impacts of Sakhalin II Phase 2 on Western Pacific Gray Whales and Related Biodiversity. IUCN, Gland Switzerland, and Cambridge, U.K. 123pp.

Reeves, R.R., Smith, B.D., Crespo, E.A. and di Sciara, G.N. (compilers) 2003. Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans. IUCN/SSC Cetacean Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.

Reilly, B. 1992. Population biology and status of eastern pacific gray whales: Recent Developments, pp.1062-1074. Wildlands 2000.

Rice, D.W. and Wolman, A.A. 1971. The life history and ecology of the gray whale (Eschrichtius robustus). American Society of Mammalogists. Special Publication 3:1-142.

Richardson, W.J., Green, C.R., Malme, C.I. and Thomson, D.H. 1995. Marine Mammals and Noise. Academic Press, San Diego, CA.

Swartz, S.L. 1986. Gray whale migratory, social and breeding behavior. Report of the International Whaling Commission, Special Issue 8:207-29.

Vladimirov, V.L. 1994. Recent distribution and abundance level of whales in Russian Far-Eastern seas. Russian Journal of Marine Biology 20:1-9.

Wang, P. 1978. Studies on the baleen whales in the Yellow Sea. Acta Zoologica Sinica 24:269-277.

Weller, D.W., Burdin, A.M., Würsig, B., Taylor, B.L. and Brownell Jr., R.L. 2002. The western Gray Whale: a review of past exploitation, current status and potential threats. Journal of Cetacean Research and Management 4: 7–12.

Weller, D.W., Würsig, B., Bradford, A.L., Burdin, A.M., Blokhin, S.A., Minakuchi, H. and Brownell Jr., R.L. 1999. Gray whales (Eschrichtius robustus) off Sakhalin Island, Russia: seasonal and annual patterns of occurrence. Marine Mammal Science 15:1208-1227.

Weller, D.W., Würsig, B., Burdin, A.M., Reeve, S.H. and Bradford, A.L. 2000. Gray Whales off Sakhalin Island, Russia: June – October 1999. A joint U.S. – Russian scientific investigation. Final contract report to Sakhalin Energy Investment Company.

Würsig, B., Weller, D.W., Burdin, A.M., Reeve, S.H., Bradford, A.L. and Blokhin, S.A. 2000. Gray whales summering off Sakhalin Island, Far East Russia: June-September 1998. A joint U.S.-Russian scientific investigation. Final Contact Report to Sakhalin Energy Investment Company and Exxon Neftegas.

Zhou, K. and Wang, X. 1994. Brief review of passive fishing gear and incidental catches of small cetaceans in Chinese waters. Report of the International Whaling Commission, Special Issue 15: 347-354.

Zhu, Q. and Yue, H. 1998. Strandings and sightings of the western Pacific stock of gray whale (Eschrichtius robustus) in Chinese coastal waters. Paper SC/50/AS5 presented to the IWC Scientific Committee, June 1998.

Citation: Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. 2008. Eschrichtius robustus (western subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <>. Downloaded on 17 April 2014.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please fill in the feedback form so that we can correct or extend the information provided