Authorities are investigating the sudden deaths of six grey whales found in the San Francisco Bay area between May 21 and May 28, 2025. These recent deaths add to a concerning number of whale fatalities reported in the region this year, prompting conservationists to highlight the challenges marine mammals face in busy coastal environments.
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Recent Deaths and Investigations
The California Academy of Sciences and the Marine Mammal Center confirmed the six grey whale deaths occurred over a single week. On May 28, one grey whale was discovered near Alamere Falls. Just two days prior, on May 26, two more were reported dead – one near Alcatraz Island and another at Point Bonita in Marin County.
Earlier in the week, a female grey whale died near Berkeley on May 24. Another was found in Fisherman’s Bay on Southeast Farallon Island, off the San Francisco coast, on May 22. The first of the six recent fatalities was a yearling grey whale discovered in Bolinas in Marin County on May 21.
Necropsies (animal autopsies) are being conducted to determine the causes of death. However, officials from the California Academy of Sciences note that these investigations are challenging. Factors such as inaccessible locations hindering access, advanced decomposition affecting tissue quality, and a lack of suitable towing sites complicate the process.
Challenges in Determining Cause
As of May 28, a necropsy was performed on a subadult male whale at Kirby Cove in the Marin Headlands, suspected to be one of the individuals sighted on May 26. The cause of this death, like the others, remains under investigation.
The recent findings bring the total number of dead whales discovered in the Bay Area in 2025 to 14. While the cause for the latest six deaths is still being determined, the California Academy of Sciences has confirmed that three of the overall 14 deaths in 2025 were suspected or likely due to vessel strikes.
Increased Whale Sightings in the Bay
The Marine Mammal Center’s Cetacean Conservation Biology Team has noted an unusually high number of grey whale sightings within the San Francisco Bay this year. They have confirmed 33 individual grey whales via photo identification, a significant increase compared to only six sightings in the bay during 2024.
Roughly one-third of these whales have remained in the bay for at least 20 days. Researchers are investigating the reasons behind this substantial spike in whale presence within the busy commercial environment of the bay. The overall body condition of these observed whales has varied from normal to emaciated.
Experts anticipate that grey whales will continue to be present in the bay for approximately one to two more weeks before continuing their annual northern migration towards Arctic feeding grounds. The recent increase in deaths is particularly concerning to the Marine Mammal Center, calling it the most deaths seen since the “Unusual Mortality Event” a few years ago, which resulted in a roughly 45% decline in the species’ population.
Warnings for Boaters
With the San Francisco Bay serving as a shared space and experiencing heightened grey whale activity, experts are urging all boaters to be “whale aware.” This includes large commercial vessels and smaller sailboats alike. Boaters are advised to slow down.
Grey whales often have a low profile in the water, making them difficult to spot compared to other coastal species like humpback whales. The Marine Mammal Center is collaborating with the San Francisco Harbor Safety Committee to implement solutions to reduce the risk of vessel strikes. Efforts include potentially altering ferry lanes based on current sighting data and increasing communication announcements to mariners via the U.S. Coast Guard about heightened whale activity.
People observing the body of a deceased grey whale washed ashore on Huntington Beach, California.
Similar Events in Canada
Concerns over grey whale deaths are not limited to California. Several grey whales have also washed ashore in British Columbia during the same month. On May 11, a second dead grey whale was reported in Haida Gwaii, near Skidegate.
This followed a report on May 6 from Parks Canada about a dead whale spotted floating off Vancouver Island before it eventually washed ashore on Long Beach in Pacific Rim National Park Reserve near Tofino. The cause of these deaths in Canada is also under investigation, with necropsy reports potentially taking up to three months to provide clarity.
Handout photo of a deceased grey whale washed ashore on Long Beach, British Columbia, provided by Parks Canada.
Authorities in Canada have advised the public against touching dead whales and recommend keeping dogs leashed near carcasses. They also ask anyone who witnesses whales being harassed or disturbed to report the activity immediately.
In the San Francisco Bay Area, the public is encouraged to report dead, injured, or stranded marine mammals by contacting the California Academy of Sciences for deceased animals or the Marine Mammal Center for live animals. Whale sightings can also be reported via the Whale Alert app or on the Marine Mammal Center’s website.
