A 36-foot dead female gray whale rests on sand at Black Sands Beach in Golden Gate National Recreation Area, north of Shelter Cove, Calif., on Monday, March 31, 2025. Experts from The Marine Mammal Center and partners at the California Academy of Sciences were to perform a necropsy, or animal autopsy. A cause of death is not known at on Monday. (The Marine Mammal Center via Bay City News)
The San Francisco Bay has been hosting an influx of gray whales over the past week or so, including one that was found floating dead near Alcatraz Island on Saturday.
Since the whales started hanging out in the Bay, there have been multiple sightings and experts from the Marin Headlands-based Marine Mammal Center are advising boaters to be careful while out on the water because, while famously large, the animals are sometimes difficult to spot.
"While this number of gray whales in San Francisco Bay is exciting to see, it does raise concerns for both human and whale safety," says Kathi George, director of cetacean conservation biology at the center. "Gray whales are difficult to see due to their low profile and coloration patterns that naturally blend into the bay. It's important for all boaters to be extra vigilant and whale aware."
As for the dead whale, it was first spotted Saturday morning and personnel from the center and the California Academy of Sciences boated out to take tissue samples, photos and tag it with a buoy.
By Sunday, the whale had drifted under the Golden Gate Bridge, out of the bay and onto Black Sands Beach in the Golden Gate National Recreation Area on the Marin Headlands.
That's where a team of scientists was able to conduct a necropsy on the 36-foot whale Monday, according to Marine Mammal Center officials.
While it's still unclear what killed the animal -- the first dead whale found in the region this year -- it was found to be emaciated and was likely a "subadult" female.
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There was no initial evidence of blunt force trauma from being hit by a boat, one of the top threats to gray whale safety.
Tests on the dead whale's tissue samples to determine its cause of death can take several weeks to conduct.
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People can report dead, injured or stranded marine mammals in the San Francisco Bay Area by calling the California Academy of Sciences at (415) 379-5381 for dead animals or the Marine Mammal Center at (415) 289-7325 for live animals.
People can also download a whale alert app at conserve.io.
