Hundreds of gray whales are dying in ‘unusual’ event not seen in decades, experts say

Hundreds of gray whales are dying off the West Coast in an “unusual” event not seen in decades, the National Oceanic and Atmospheric Administration reported.

Since Jan. 1, 2019, researchers have found at least 386 gray whales stranded along the coasts of North America, NOAA Fisheries said in a report updated Jan. 8.

The number of deaths is so large that it’s been declared an “unusual mortality event.” The last unusual mortality event for gray whales happened between 1999 and 2000, according to NOAA.

“NOAA Fisheries has declared an Unusual Mortality Event (UME) for the Eastern North Pacific stock of gray whales along the west coast of North America including Mexico, California, Oregon, Washington, British Columbia, Canada and Alaska,” NOAA reported. “Strandings began January 1, 2019 and are continuing.”

An unusual mortality event is an unexpected phenomenon during which a significant number of a marine mammal population dies. The event “demands immediate response” and meets some of seven criteria, according to NOAA.

Experts determined that the gray whales’ deaths met two pieces of criteria, including an increase in the magnitude or marking a change in mortality compared with previous data. The whales also showed unusual findings or signs.

Researchers don’t know what is causing the whale strandings, but it is possible that the animals are not eating enough during the spring and summer to make the full migration to the Arctic, NOAA reported.

“They ‘place their bets’ during the summer/fall feeding season when they seek to consume enough food to survive the following six months, as they do not feed extensively during their migration or their winter in Mexico,” NOAA said. “The gray whales likely face the greatest nutritional stress during the northbound migration off the West Coast, when they may be reaching the limits of their fat stores.”

This story was originally published January 12, 2021 at 2:19 PM with the headline "Hundreds of gray whales are dying in ‘unusual’ event not seen in decades, experts say."