Marine Mammal Commission

Western North Pacific Gray Whale

The Western North Pacific population of gray whales historically migrated along the coasts of Russia, Korea, China, and Japan and was thought to be extinct after being decimated by commercial whaling before the 1970s. A small population of gray whales was discovered in the 1990s off Sakhalin Island, Russia, and current conservation efforts focus on mitigating the impacts of rapidly expanding offshore oil and gas development in the region. Satellite telemetry, photo-identification, and genetic studies are providing new insights on the movements and phenology of gray whales throughout the North Pacific and raising new questions concerning the relationships of the Sakhalin whales to other gray whales in the North Pacific.

Gray whale

Gray whales are known for their long annual migration between their feeding and breeding grounds.

Species Status

The Western North Pacific population of gray whales is listed as endangered under U.S. law and designated critically endangered on the Red List of the International Union for Conservation of Nature (IUCN). Until a few animals were discovered at Sakhalin Island, Russia, in the 1990s, this population was thought to have been extirpated by commercial whaling prior to the 1970s. In summer and fall, many of the whales in this population forage off the Northeastern coast of Sakhalin Island, but their migratory routes and winter/breeding habitat are poorly known. They are thought to have ranged southwest to traditional breeding and calving grounds along the coasts of Korea, Japan, and China. The 2013 abundance estimate (excluding calves), estimated from photo-identification of the animals of Northeastern Sakhalin Island data, was 154 animals with roughly 40 reproductive females. Contemporary records of gray whales off Japan and the Asia mainland to the south of Sakhalin are rare, however, with fewer than 20 from Japanese waters between 1990 and 2015 and 24 from Chinese waters since 1933. The last known record of a gray whale off Korea was in 1977. While recent observations of gray whales off the coasts of Japan and mainland Asia are infrequent, they nevertheless continue to occur, including a photo-identified gray whale observed moving multiple times back and forth between Sakhalin Island, Russia and the Pacific coast of Honshu, Japan between 2014 and 2016. A 13-m female was taken in fishing gear offshore of Baiqingxiang, China, in the Taiwan Strait in November 2011. Since 2010, documentation of movement of gray whales between the Western and Eastern North Pacific indicates a significant portion of the animals occupying the feeding grounds at Sakhalin Island migrate to the Eastern North Pacific to breed and give birth in the winter and then return to Russia to feed.

The discovery of gray whales at Sakhalin Island, coincided with strong interest in the area for oil and gas development, with a focus on the nearshore waters immediately outside Piltun Lagoon. This caused grave concern over the potential impacts of such development on the very small population of whales that concentrate in this area in the summer and fall of each year. In 2006, IUCN’s Western Gray Whale Advisory Panel was established to work with the operators of one of the larger oil and gas projects at Sakhalin, the Sakhalin oil development project to provide independent advice and recommendations on how the company can minimize risks to the whales and their habitat associated with its operations, particularly seismic surveys, construction noise and vessel operations, oil spill response and environmental monitoring. There is also concern about threats in other seasons and other areas further south. As evidenced by recent deaths in fishing nets in Japan and China, gray whales migrating to the southwest from Sakhalin to Korea, Japan, and China face this risk as well as that of ship strike.

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 breeding and calving 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 the Mexican breeding and calving grounds during the winter. The International Whaling Commission’s (IWC’s) Scientific Committee has conducted a rangewide review of population structure and status of North Pacific gray whales.

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 at Sakhalin Island and ensure the adequacy and effectiveness of mitigation measures to minimize impacts on the small number of whales feeding there. The North Pacific basin-wide assessment of gray whale population structure and movements that is being carried out by the IWC Scientific Committee is important for understanding the status of stocks and the threats they face. An important consideration is whether individuals from the Western North Pacific that migrate seasonally to coastal North American waters could be taken by whalers from the Makah Tribe in Washington State.

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

Letter Date Letter Description
July 31, 2015

Letter to NMFS on the draft Environmental Impact Statement regarding the Makah Tribe’s request to resume hunting gray whales

April 24, 2013

Letter to NMFS regarding a permit application from Yoko Mitani, Ph.D., to conduct research on killer and gray whales in Alaskan waters

Learn More

Science Provides Clues about Whale Migration

Satellite telemetry, photo-identification, and genetic studies have documented the movements of individual gray whales between feeding grounds in the Western North Pacific and breeding grounds 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., 2011a). Six additional tags were deployed in summer 2011 and by the end of December two continued to function. These tags were on young females that 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 calving lagoons, along the 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 at Sakhalin where her movements were recorded until the tag ceased to function on or about October 14, 2012 (IWC, 2012). The 22,511 km round trip took 172 days and is the longest recorded migration of any mammal.

These fascinating tracking results spurred analysis of photo-identification and genetic data. The results of a comparison of the 217 photo-identified gray whales at Sakhalin Island with the 6,546 individuals in the photo-identification catalogue for Baja California, Mexico, were reported to the IWC Scientific Committee meeting in June 2012. Thirteen matches were identified between these two areas: 6 males, 6 females, and 2 of unknown sex (IWC, 2012). Twelve of the whales were sighted in Russia both before and after they were sighted in Baja California, and five of the females were observed with calves in Russia in summer. Two of these mother-calf pairs were sighted together in Russia; the other three mothers were inferred to have separated from their calves (i.e., likely due to weaning) or lost their calves before being sighted alone at Sakhalin.

Genetic matches between two animals biopsied off Santa Barbara, California and known from both biopsies and photo-identification at Sakhalin Island provided further evidence of the connection between the Western and Eastern Pacific.


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 Western 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

In 2006, IUCN’s Western Gray Whale Advisory Panel was established to work with the operators of one of the larger oil and gas projects at Sakhalin, the Sakhalin oil development project to provide independent advice and recommendations on how the company can minimize risks to the whales and their habitat associated with its operations, particularly seismic surveys, construction noise and vessel operations, oil spill response and environmental monitoring. The IWC’s Scientific Committee is leading efforts to understand the movements of gray whales across the North Pacific basin and the implications for population structure.

Additional Resources

Since 2004, IUCN has worked with Sakhalin Energy to provide advice and recommendations on how the company can minimize risks associated with its operations on the Sakhalin gray whales and their habitat. As one part of this broad initiative, IUCN created a panel of independent scientists in 2006 – the Western Gray Whale Advisory Panel (WGWAP) – which provides scientific advice and recommendations on the company’s operational plans and mitigation measures.