Four decades after the whaling ban, Blue Whales are re-establishing old migration patterns

U.S. and Canadian scientists have documented the first known migration of blue whales from the coast of California to areas off British Columbia and the Gulf of Alaska since the 1965 ban of commercial whaling.

Researchers identified 15 separate cases where Blue Whales were spotted in the waters off British Columbia and the Gulf of Alaska. Four of the observed animals were identified as Blue Whales previously seen swimming in Californian waters, which suggests that Blue Whales are re-establishing their old migration pattern.

The identifications were made by comparing pictures of Blue Whales photographed in the northern parts of the Pacific Ocean since 1997 with photographs of Blue Whales taken off the southern U.S. West Coast. The identity of individual Blue Whales was determined based on dorsal fin shape and pigmentation patterns in skin colour.

The Blue Whale was almost hunted to extinction during the 20^th century and even though commercial whaling has been prohibited (albeit not strictly enforced) since 1965 the populations are having a hard time recovering. Blue Whales are still listed as endangered on the IUCN Red List of Threatened Species and no more than roughly 5,000 to 12,000 Blue Whales are believed to remain in our oceans, with 2,000 of them living of the U.S. West Coast.

The migration research was conducted by scientists from Cascadia Research Collective in Washington State, NOAA’s* Southwest Fisheries Science Center in California, and Canada’s Department of Fisheries and Oceans. You can read the full article in the most recent issue of the journal Marine Mammal Science.

* The United States National Oceanic and Atmospheric Administration (NOAA)