Bay Area biologists count 5 dead whales in a week

Bay Area biologists count 5 dead whales in a week

Marine biologists told KTVU they have not seen this many dead whales in the region since what they call the "unusual mortality event" between 2019 and 2023.

SAN FRANCISCO - Researchers with the California Academy of Sciences and the Marine Mammal Center are looking into why five whales were found dead in the Bay Area within the span of a week.

Marine biologists told KTVU they have not seen this many dead whales in the region since what they call the "unusual mortality event" between 2019 and 2023.

Cal Academy reported 14 whales have died in 2025 – 13 gray whales and one minke whale.

Since May 21 alone, stranded whales died near Alcatraz, Point Bonita, Berkeley, the Farallon Islands, and Bolinas.

A dead gray whale in San Francisco Bay. Photo courtesy of The Marine Mammal Center. 

More whale sightings:

The number of deaths is high, because the number of whale sightings is at an all-time high.

"The migration is a little bit later than it has been in years past and we're seeing more whales enter San Francisco Bay," said Kathi George, Director of Cetacean Conservation Biology at the Marine Mammal Center.

This year alone, 33 gray whale sightings have been confirmed by photo identification so far. In 2024, biologists only saw four.

"The entrance to San Francisco is a very busy area with lots of vessel traffic," said George.

The possibilities:

While the causes of the most recent deaths are still under investigation, the Marine Mammal Center cites "vessel strikes" as the cause of three deaths this year in April and mid-May.

George said the Marine Mammal Center works closely with the Harbor Safety Committee in San Francisco. She said ferry operators, the Coast Guard, and other boaters know to keep an eye out and veer out of the way when they see a whale.

"It could be hard to see on a foggy day or a sunny day," George said. "So going slow, being aware that whales are in the water, are the best things that boaters can do right now."

The last time this many whale deaths were tracked was between 2019 and 2023, when biologists said whales went through an "unusual mortality event," losing more than 45% of their population. 

What's next:

They’re still looking into the reason behind the massive spike in sightings this year.

George said the gray whales are expected to stick around for another week or two before migrating north.

If you spot a whale, you're asked to take a picture and upload it to the Whale Alert app or contact the Marine Mammal Center.

A necropsy is being performed on Wednesday for the deaths, which is important for researchers to determine how to protect the species.