|Scientific Name:||Eschrichtius robustus|
|Species Authority:||(Lilljeborg, 1861)|
|Infra-specific Taxa Assessed:|
|Red List Category & Criteria:||Least Concern ver 3.1|
|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)|
When the two subpopulations are assessed as a single species-level unit, the estimated population size is above the threshold for a threatened category, and the population has increased over the last three generations. The recent apparent decline in the eastern subpopulation is considered to be a fluctuation and is not inconsistent with a Least Concern listing. The western subpopulation is listed separately as Critically Endangered.
|Range Description:||The gray whale was once found in the North Atlantic. Sub-fossil remains, the most recent dated at around 1675, have been found on the eastern seaboard of North America from Florida to New Jersey and on the coasts of the English Channel and the North and Baltic seas. There are historical accounts of living gray whales from Iceland in the early 1600s and possibly off New England (USA) in the early 1700s (Rice 1998).
Gray whales are now only found in the North Pacific and adjacent waters. The larger eastern North Pacific population summers and feeds mainly in the shallow waters of the Chukchi and Beaufort seas, and the northwestern Bering Sea; a few also summer and feed along the Pacific coast from Vancouver Island (Canada) to central California (US). The population migrates in autumn along the coast to winter breeding grounds on the west coast of Baja California (Mexico) and the southeastern Gulf of California. Some calves are born during the southward migration but most are born in shallow bays and lagoons on the west coast of Baja California (Jones and Swartz 2002).
The much smaller western subpopulation summers in the Okhotsk Sea. The major known feeding grounds are off the northeastern coast of Sakhalin Island (Russian Federation), but some animals are occasionally seen off the eastern coast of Kamchatka (Russian Federation) and in other coastal waters of the northern Okhotsk Sea. Its migration routes and winter breeding grounds are poorly known, the only recent information being from occasional records on both the eastern and western coasts of Japan and along the Chinese coast (Weller et al. 2002; see separate listing of this subpopulation for more information).
Native:Canada; Mexico; Russian Federation; United States
Vagrant:China; Japan; Korea, Democratic People's Republic of; Korea, Republic of
|FAO Marine Fishing Areas:||
Arctic Sea; Pacific – eastern central; Pacific – northeast; Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
Genetic studies and differential recovery patterns (LeDuc et al. 2002) suggest that the small western North Pacific subpopulation is isolated from the larger eastern subpopulation. The former is listed as Critically Endangered (see separate account).
Both eastern and western gray whales were hunted in prehistoric times, but aboriginal catches declined to relatively low levels by the early 20th century due to depletion of the stocks by commercial whaling and the general decline of the traditional aboriginal economies (Mitchell and Reeves 1990).
Eastern gray whales were rapidly depleted by commercial whalers operating in the breeding lagoons when they were discovered in the mid-19th century, estimated peak catches (averaging over 480 whales per year) occurring between 1855 and 1865. Lagoon whaling ended by about 1875, apparently due to exhaustion of the lagoon populations, but shore-based whaling in California continued at a lower level until the late 19th century (Henderson 1984; IWC 1993). In the 20th century, there were some pelagic catches off California and Mexico by Norwegian and American vessels in the 1920s and 1930s, and in the 1930s and 1940s by a Soviet pelagic fleet in the Bering and Chuckchi Seas (Donahue and Brownell 2001; Brownell and Swartz 2006). A further 320 gray whales were taken under scientific permit in the 1960s (Rice and Wolman 1971), and 138 illegal Soviet catches occurred in the 1960s (Doroshenko 2000). Substantial “aboriginal subsistence” whaling in the Bering and Chukchi seas off Chukotka (Russian Federation) resumed in 1948 and has continued into the present, apart from an interruption in the early 1990s during the collapse of the USSR. Catches during the last 50 years (1956-2005) have averaged around 150 per year. Very small numbers have also been taken by aboriginal whalers in Alaska (US), and, in recent years, by the Makah tribe in Washington State, (US) (Donahue and Brownell 2001; IWC 2005).
Despite the continuing catches, the eastern subpopulation has recovered strongly from past over-exploitation, increasing by 2.5% per annum during 1967-96 (Buckland and Breiwick 2002). The subpopulation seems to have peaked around 1997/98 when a census on the southward migration indicated a population of 24,000-36,000; it may have declined since the most recent estimate is 15,000-22,000 for 2001/02 (Rugh et al. 2005). However, there are a number of unresolved possible explanations for the downturn, inter alia related to an ‘overshoot’ of carrying capacity (Moore et al. 2001) and/or unusual environmental conditions around the turn of the millennium resulting in poor calf production, high stranding rates and relatively high numbers of emaciated animals (e.g. LeBouef et al. 2000, IWC 2003, Rugh et al. 2005). Perryman et al. (2002) showed that calf production was related to the proportion of feeding habitat free of sea ice in the preceding summer. Since 2002, calf production has recovered, and mortality and the occurrence of emaciated whales have declined (IWC 2004). The population has probably reached a size where it exceeds the carrying capacity of the environment in years where food availability is below average and is likely to fluctuate around some environmentally determined average level (IWC 2003).
The western Pacific subpopulation remains at a small fraction of past levels and is estimated to number about 100 individuals, of which 20-30 are mature females (Reeves et al. 2005), based on analysis of photo-identification data (see separate listing for the western Pacific subpopulation for more information).
|Habitat and Ecology:||
Gray whales are primarily bottom feeders and are thus restricted to shallow continental shelf waters for feeding. They are largely coastal although they do feed at greater distances from shore on the shallow shelf of the Bering and Chukchi seas.
Gray whales feed primarily on swarming mysids, tube-dwelling amphipods, and polychaete tube worms in the northern parts of their range, but are also known to take red crabs, baitfish, and other food (crab larvae, mobile amphipods, herring eggs and larvae, cephalopods, and megalops) opportunistically or off the main feeding grounds.
Gray whales have been subject to hunting since prehistoric times, due to their slow swimming speeds and coastal distribution. The North Atlantic population was extinct by the early 1700s, although the causes are unclear. Over-exploitation was thought to have caused the extinction of the western gray whale until Soviet scientists in the 1980s reported a small remnant group summering off Sakhalin Island. The eastern North Pacific subpopulation had reached such low numbers by the end of the 19th century that commercial whaling ceased, but it has now recovered to at or near carrying capacity, its abundance showing some fluctuation in response to environmental conditions.
The eastern North Pacific subpopulation is subject to anthropogenic threats such as entanglements in fishing gear (Baird et al. 2002), disturbance by vessels and other noise, collisions, and possibly petroleum-related and other contaminants (Moore and Clarke 2002). However, these do not appear to be having a significant effect on the demography of the population.
Gray whales have been protected from commercial whaling by the International Whaling Commission (IWC) since its establishment in 1946. Limited aboriginal subsistence whaling is permitted by the IWC for the eastern gray whale and catch limits have been set since the 1970s on the basis of advice from its Scientific Committee (most recently under its new aboriginal subsistence whaling management procedure) and a needs request from the relevant governments (Russian Federation and US). The current (2003-07) catch limit for the eastern stock is 620 for five years, subject to a maximum of 140 in any single year. This meets the needs request and is considerably below the estimated level (over 400) that would be sustainable (IWC 2005).
Three gray whale breeding lagoons in Mexico (Laguna Ojo de Liebre, L. San Ignacio and L. Guerrero Negro) enjoy some protection in the form of limitations on boating, fishing and coastal development, originally as National Gray Whale Refuges, now through their inclusions in the El Vizcaino Biosphere Reserve, which is also listed internationally as a UNESCO World Heritage Site and a Ramsar protected wetland (Hoyt 2005).
The species is listed in Appendix I of CITES and Appendix II of CMS.
|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. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 05 December 2013.|
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