6 gray whales have died in San Francisco in the past week as authorities scramble for answers
Six gray whales have died in the San Francisco Bay area in just the past week alone, bringing the total number of stranded whales to 15 so far this year as authorities rush to figure out what could be causing the sudden deaths.
The California Academy of Sciences and their partners at the Marine Mammal Center confirmed that six gray whales died between May 21 and May 28 and that their necropsy response efforts to figure out what is going on has been “challenging.”
“Necropsy response efforts and data collection have been challenging for a number of cases due to inaccessible locations that hinder full post-mortem investigations, as well as poor tissue quality from advanced decomposition, and the lack of available locations to tow for further investigation,” officials said. “As of today, May 28, 2025, a necropsy (animal autopsy) was conducted at Kirby Cove in the Marin Headlands. It is suspected that this subadult male is one of the two whales that was sighted on May 26, 2025. The cause of death is still under investigation. The other individual has not made landfall.”
So far in 2025, 15 whales in total have died -- 14 gray whales and one minke whale -- in the greater San Francisco Bay area, with the causes of at least three of the gray whale deaths being suspected to have been caused by vessel strikes, officials said.
“The Academy and partners at the Center have not responded to this many dead gray whales since the height of the Unusual Mortality Event in 2019 (14 individuals) and 2021 (15 individuals),” scientists confirmed.
In 2025, scientists have reported “an unusually high number of sightings in the San Francisco Bay this year, with 33 individual gray whales confirmed. In 2024, only six gray whales were sighted over the entire year.
“Roughly one-third of [the whales this year] have stayed in the bay for at least 20 days, and their overall body condition has ranged from normal to emaciated,” scientists said. “The reason or potential reasons behind the massive spike in sightings this year are still being investigated by researchers. It is expected that gray whales will be in the bay for another one to two weeks before continuing their annual northern migration to arctic feeding grounds.”
The long-term outlook for gray whales in the aftermath of the 2019 to 2023 unusual mortality event saw a population loss of roughly 45% and observation scientists in southern California reported record-low calf counts earlier this year -- a cause for concern, according to scientists.
“With San Francisco Bay serving as a shared space for commerce and increased gray whale activity, experts at the Academy and the Center note it’s vital that all boaters -- from large commercial vessels to sailboats -- be “whale aware” and continue to slow down,” officials warned.
“Gray whales often have a very low profile in the water that can make them difficult to sight, unlike other coastal whales like humpback whales,” scientists continued. “The Center is working with the San Francisco Harbor Safety Committee to find solutions to reduce the risk of vessel strike (including altering ferry lanes based on sighting data this year) and increase mariner communication announcements of heightened whale activity via the U.S. Coast Guard.”
