Most eastern North Pacific gray whales migrate seasonally from breeding areas in Mexico to primary feeding areas in the Arctic but recent research has revealed a more complex and extensive use of the Salish Sea and surrounding waters. The Pacific Coast Feeding Group (PCFG) represents about 150 gray whales that feed in spring through fall from N California to SE Alaska. Genetics and photo-identification have revealed that this group is relatively stable and distinct from the gray whales that feed in the Arctic, though some interchange has been documented and these animals interbreed in Mexico. The PCFG whales feed on a variety of prey including Mysid shrimp in the Pacific Northwest mostly outside the Salish Sea, but also extending into the Strait of Juan de Fuca. Separate from the PCFG, a number of areas inside the Salish Sea also appear to be seasonal feeding areas for a small number of gray whales that break off from their migration before continuing their migration north. One area this has been studied is in northern Puget Sound especially around Whidbey Island including the Snohomish Delta and Port Susan. Primarily from March to May, just under a dozen gray whales feed for several months apparently targeting ghost shrimp in several intertidal areas. Photo-identification of gray whales has revealed it is primarily the same individual whales that have returned annually at least going back to the early 1990s. Recent research using suction cup attached video tags on whales has provided new insights into their feeding and social interactions in this area. In collaboration with the Washington DNR, research has examined the extent of feeding on ghost shrimp and potential conflicts with a commercial harvest in this area.
Citation:
Calambokidis, J., A. Perez, and N. Harrison, 2016. New research reveals more complex role of gray whales in the Pacific Northwest including the Salish Sea. Presentation at Salish Sea Ecosystem Conference, Vancouver, BC. 13-15 April 2016.