Fifth gray whale washes ashore in Washington this year. What’s going on?

For the fifth time this year, a dead gray whale washed up on a shore in Washington ⁠— this time on Bainbridge Island, KIRO 7 reported.

It follows a trend that started in 2019, when 123 whales washed up on the West Coast ⁠— 34 of which were in Washington state, according to the National Oceanic and Atmospheric Administration (NOAA). That prompted researchers to declare an Unusual Mortality Event (UME), The Seattle Times reported.

The most recent whale was an adult that appeared to have been dead for a while, according to the Kitsap Sun. The whale’s carcass was towed off the beach to assess what might have killed the whale and how healthy it was before it died, the Kitsap Sun reported.

“Something has changed with their food supply in the Arctic in some way, but it’s not clear what that change is. That’s what we’re trying to figure out,” said Michael Milstein, a spokesman for NOAA Fisheries West Coast region, according to the Times.

Several of the whales found this year have been unusually thin, which might indicate an issue with their food supply, KIRO reported. The overall population of gray whales is still fairly strong and the species is no longer considered endangered, but the recent increase in dead whales has prompted researchers to look for answers, according to the Sun.

A similar situation happened between 1999 and 2000, when an UME last occurred, the Times reported. Some researchers theorize that the previous event as well as the more recent UME has something to do with the 1972 hunting ban, which allowed the gray whale population to grow to a point that may have “reached the environment’s carrying capacity,” according to the Times.

Data from NOAA show that most dead whales have been found on the West Coast between March and July in the past, according to the agency’s website. More research needs to be done to determine the actual cause of the most recent UME, NOAA said.