Each year, from mid-February to May, eastern North Pacific gray whales migrate northward along the West Coast, but in recent years more have been dying on the journey. Last year, 179 gray whales died during migration season, 18 of them in Washington State, said John Calambokidis, a research biologist with the Cascadia Research Collective, which had been tracking the whale. On Monday, the collective conducted a necropsy.
Scientists don’t know exactly what is causing the spike in deaths, Mr. Calambokidis said, but they think that the deaths could be connected to the whales’ food sources in the Arctic, which have been dwindling as climate change transforms the region.
From 2019 to 2023, scientists with the National Oceanic and Atmospheric Administration documented an “unusual mortality event” in the population of whales that migrate along the West Coast of the United States. The agency’s count in winter last year indicated that the population had dwindled further, to about 13,000 gray whales — the smallest population since the 1970s.