Gray whales were once distributed throughout the northern hemisphere but now only two populations remain; one in the western North Pacific and one in the eastern North Pacific.
The eastern population of approximately 27,000 individuals ranges from the cold Arctic waters, where they spend summer months feeding in the northwestern Bering Sea and southern Chukchi and Beaufort Seas, to the warm waters of Mexico where they breed. Their migration route between these areas hugs the shore, particularly when heading north, taking the whales past the coastal cities of the western US and Canada. Each trip takes two to three months and can be up to 10,000 km long, an incredible round-trip of 20,000 km.
The distribution of the western North Pacific population of approximately 300 individuals isn’t so well known. While whaling records indicate a breeding ground once existed south of the Korean peninsula, gray whales haven’t been reported in Korean waters since 1977 and recent surveys failed to find any. There have been some sightings off the Pacific coast of Japan though, as well as some strandings and by-catch off the coast of China and in the Taiwan Strait. Feeding areas close to Sakhalin and Kamchatka, in eastern Russia, are visited by gray whales each summer. Photo-identification and satellite tagging studies have shown that some of those whales travel to the same breeding lagoons as the eastern population. However, it’s not clear whether a Korean breeding area is still in use.
Gray whale remains and whaling logs show that gray whales were also found in the western and eastern Atlantic Ocean, possibly up until the early 1700s. Although whaling is said to have caused their extinction from the Atlantic, a study looking at ancient DNA and habitat modelling suggested that gray whales in the Atlantic might have already been in decline prior to whaling. Interestingly, there have been two gray whales reported in the Atlantic Ocean more recently: a gray whale was seen in the Mediterranean – first off the coast of Israel and then off the coast of Spain – in 2010, followed by a gray whale off the coast of Namibia in 2013.
More information can be found on the IUCN Red List website.