Five gray whales have died in the greater Bay Area over the past week, bringing the region's 2025 whale death toll to 14, officials announced Wednesday.
The California Academy of Sciences and The Marine Mammal Center, which announced the deaths, said they have not responded to this many dead gray whales since 15 in 2021 and 14 in 2019.
The following information about the five recent whale deaths was provided by the California Academy of Sciences and The Marine Mammal Center.
Of the 14 whale deaths this year, 13 were gray whales and one was a minke whale, officials said. The minke whale was seen in shallow waters and stranded on shore near Emeryville in April, and mammal experts ultimately decided to euthanize that whale. The cause of death for three of the gray whales was determined to be a suspected or probable vessel strike. The cause of death for the other whales wasn't immediately known.
There has been an "unusually high" number of whale sightings in and around the San Francisco Bay this year, according to officials. So far, 33 gray whales have been spotted in the area, compared to just four gray whale sightings in 2024. About one-third of the whales this year have stayed in the Bay for at least 20 days. Their body conditions ranged from normal to emaciated.
On Wednesday, the deceased whale in Berkeley could be seen floating in the water. At Kirby Cove in the Marin headlands, just west of the Golden Gate Bridge, one deceased, young male gray whale washed up on shore. On Wednesday, a team of scientists from Cal Academy and the Marine Mammal Center performed a necropsy on that whale.
Giancarlo Rulli, a spokesperson for the Sausalito-based Marine Mammal Center, said the scientists haven't found anything unusual that would point to this whale's cause of death yet. However, Rulli noted, as this whale is a large animal, as its body decomposes, scientists may have additional chances to gather clues as to what led to its untimely death.
Rulli recognizes that many people are wondering why the San Francisco Bay Area is seeing so many whale deaths lately.
"That is the open question, the why," Rulli acknowledged.
"Why not only are there so many deceased whales in the region, but why has it been a banner year of having more sightings in San Francisco Bay of live whales than we have seen in at least two plus decades-- if ever?"
Researchers are still trying to pinpoint a reason or reasons for the jump in sightings this year, officials said.
"It is indeed a mystery that those of us in the scientific community that are watching along with you all are puzzling over," noted Doug McCauley, the director of the Benioff Ocean Science Laboratory and professor of ocean science at the University of California, Santa Barbara.
McCauley added, "The real concern is around some of the gray whales that are there in the bay right now, and those are many that are showing up here on our graph that are turning up dead."
McCauley explained that these gray whales travel from their feeding grounds in Alaska down to Mexico, where they breed in warmer waters, then travel back up the Pacific Ocean, past California, and return ultimately to Alaska.
"Unfortunately, it seems that some our our gray whales are simply running out of steam," he continued.
From 2019 through 2023, around 45% of the North Pacific gray whale population died off. Scientists have attributed the large number of deaths in the population to changes in the whales' food supply in the Arctic.
"What's happening is that climate change is disrupting their food source in the Arctic where they depart, and in Alaska, where they depart for the migration," McCauley said.
He likened the process to going for a road trip, for example, from Monterey to San Francisco, but not filling up on enough gas to complete the trip.
The gray whales, he said, "they're running low on gas, coming to the bay, searching for food, and many are starving."
The Marine Mammal Center said it's possible the same factors are contributing to the whale deaths we have seen near San Francisco this year. Rulli, with the Marine Mammal Center, noted that these deaths are another challenge for the population of whales, which is trying to recover following the significant number of deaths between 2019 and 2023.
"What we are seeing now is potentially that aftermath," Ruli added.
As researchers continue searching for answers about what's driving these changes, scientists are urging the public to report sightings of whales-- dead or alive.
Rulli recommends downloading the free Whale Alert app on your phone, which can let the public or researchers know where you spotted a whale.
The public can also report whale sightings directly to the Marine Mammal Center.
Or, if you spot a whale that has washed ashore, you can report that to either the Marine Mammal Center or the California Academy of Sciences.
At Kirby Cove on Wednesday, some hikers made the trek from the viewpoint down to the beach and were surprised to see the deceased whale on shore.
"I saw a beautiful beach and a dead whale," noted Laetitia Fisher, who was visiting San Francisco from Munich, Germany.
"It really stank, the smell was crazy," she noted.
"I've never seen a whale before, it's sad that it's a dead whale, but it was also kind of amazing to see," she said.
Gray whales are expected to linger in the Bay for roughly one to two more weeks before they continue on their northern migration, officials said.