Western North Pacific Gray Whales

Species Status

The western North Pacific population of gray whales is listed as an endangered stock under U.S. law and on the Red List of the International Union for Conservation of Nature (IUCN).In summer and fall, gray whales forage off the northeastern coast of Sakhalin and along the southeastern Kamchatka Peninsula, but the migratory routes and winter habitats of some of these whales are uncertain. Gray whales historically ranged southward from the Sea of Okhotsk, along the coasts of Korea and Japan to traditional wintering areas in southern China. Documentation since 2010, however, has shown that a significant portion of the Sakhalin gray whales migrate across the southern Bering Sea and Gulf of Alaska to Mexico for the winter and then return to Russia in spring.

In 2018, based on photo-identification and genetic data, there were about 240 whales (excluding calves) in the Sakhalin population, which was increasing at close to 5% per year. While observations of gray whales off the coasts of Japan and mainland Asia are infrequent today, they nevertheless have continued to occur. A photo-identified individual moved back and forth between Sakhalin and the Pacific coast of Honshu, Japan between 2014 and 2016, and a 13-m female died in fishing gear off Baiqingxiang, China, in the Taiwan Strait in November 2011.

The discovery of gray whales at Sakhalin Island in the 1990s coincided with growing interest in the area for offshore oil and gas development. This raised concern about the potential impacts of such development on the whales. In 2006, IUCN’s Western Gray Whale Advisory Panel was established to provide independent advice and recommendations on how the operator of one of the largest oil and gas projects at Sakhalin could minimize risks to the whales from its activities, particularly seismic surveys, construction, vessel operations, and oil spills. There is also concern about threats to gray whales in other seasons and other parts of their range in the western North Pacific. As evidenced by the recent deaths in fishing nets in Japan and China as well as observations of entangled animals at Sakhalin, gray whales in Russia, Japan, and China (and Korea if any still venture into those waters) face the risk of gear entanglement as well as that of ship strike.

The International Whaling Commission’s (IWC’s) Scientific Committee recently completed a range-wide review of population structure and status of gray whales throughout the North Pacific. Until recently, the gray whales in the eastern and western North Pacific were thought to be entirely separate. While there is evidence that some of those that feed off Sakhalin move south to at least Japan in the winter, it is uncertain to what extent the traditional wintering areas in Asia are still used. Photographic and genetic matches, as well as satellite tracking results, have shown that substantial numbers of the Sakhalin whales migrate to Mexico in winter, but recent acoustic evidence from the U.S. Navy has been interpreted as suggesting that some gray whales move through the East China Sea, travelling south in the fall and north in the spring.

What the Commission Is Doing

The Marine Mammal Commission acknowledges the efforts of IUCN’s Western Gray Whale Advisory Panel and its work with Sakhalin Energy and other companies to assess planned oil and gas development activities and ensure the adequacy and effectiveness of mitigation measures to minimize impacts on the whales feeding off Sakhalin. The North Pacific basin-wide assessment of gray whale population structure and status that was carried out by the IWC Scientific Committee improved understanding of the status of stocks and the threats they face. One important consideration from the Commission’s perspective is that should an MMPA waiver be granted allowing the Makah tribe in Washington State to resume a subsistence hunt, it should ensure, to the greatest extent possible, the protection of individuals from the western North Pacific that migrate seasonally to coastal North American waters.

Commission Reports and Publications

For more information on Western North Pacific gray whales, see the Commission’s 2010–2011 annual report and 2012 annual report.

Commission Letters

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Science Provides Clues about Whale Migration

Satellite telemetry, photo-identification, and genetic studies have documented the movements of individual gray whales between feeding areas in the western North Pacific and wintering areas in Baja California, Mexico.

A Russia-U.S. research team satellite-tagged gray whales at Sakhalin Island in 2010 and 2011. In the first successful deployment on October 4, 2010 the investigators tagged a 13-year old male gray whale in the feeding area off Piltun Lagoon along the northeastern Sakhalin coast. The whale, nicknamed “Flex,” remained within 45 km of the tagging site for 68 days and left Sakhalin on December 11. Over the next 55 days, Flex migrated across the Okhotsk Sea, the Bering Sea, and the Gulf of Alaska. The tag stopped sending signals on February 5, 2011 when Flex was 20 km off the central Oregon coast (Mate et al., 2015). Six additional tags were deployed in summer 2011 and at the end of December two, both on young females, were still functioning. These two whales moved on separate tracks away from Sakhalin, east across the Okhotsk Sea to the Kamchatka Peninsula, around its southern tip, and then eastward across the Bering Sea toward Alaska. At the end of December 2011, they were still on separate tracks, but both were southeast of the Aleutian Islands in the Gulf of Alaska. While one signal was soon lost, the transmitter on one of these whales, an 8.5-year-old female nicknamed “Varvara,” continued to transmit until the autumn of 2012. After January 1, 2012, the whale continued to travel south from British Columbia, Canada, along the west coast of the United States and Mexico to almost the southern tip of Baja California. At that point, the whale reversed course and returned north past the major nursery lagoons, along the west coast to Alaska, through the Aleutians and back across the Bering Sea. These migratory movements and this whale’s presence in or near the wintering lagoons coincided with the migratory timing of eastern North Pacific gray whales. By mid-May, Varvara had returned to the original tagging area off Sakhalin where her movements were recorded until the tag ceased to function on or about October 14, 2012. The 22,511 km round trip took 172 days and is the longest recorded migration of any mammal.

These fascinating tracking results spurred analyses of photo-identification and genetic data which were reported at the 68th meeting of the International Whaling Commission Scientific Committee. As of 2019, 54 different individual gray whales were known to have visited both Russia and Mexico, confirming that at least 14% of the Sakhalin-Kamchatka whales make the trans-Pacific migration (if not annually at least in some years) and about 0.5% of the whales that have been photo-identified in the Mexican wintering areas are individuals that also visit Russia in summer and fall. At least 20% of the Sakhalin whales are believed to migrate to wintering areas somewhere in Asia.

Genetic matches between two individual gray whales biopsy-sampled off Santa Barbara, California and known from both biopsies and photo-identification at Sakhalin provided further evidence of the connection between the western and eastern Pacific.

Threats

The threats to gray whales in the western North Pacific include entanglement and entrapment in fishing gear, ship strikes, noise, and habitat degradation. The whales that migrate to North America for the winter face these same threats there. The intensity of oil and gas exploration, development, production, and transport at Sakhalin Island is of particular concern as a potential threat to the gray whales that depend on that region for foraging in the summer and fall.

Current Conservation Efforts

Since 2004, the International Union for Conservation of Nature has been working with Sakhalin Energy Investment Company, the operator of one of the largest oil and gas projects at Sakhalin, to provide independent advice on how the company can minimize and monitor risks to the whales and their habitat from seismic surveys, construction noise, vessel operations, and oil spills. Also, for more than 20 years the International Whaling Commission and its Scientific Committee have provided an international forum for improving knowledge about western gray whales and drawing attention to the threats they face and the measures needed to conserve them.