Spike in whale mortality raises environmental concerns in California waters
San Francisco, June 1, 2025 — A series of mysterious gray whale deaths in the San Francisco Bay Area has baffled marine scientists and raised alarms among conservationists. Between May 21 and 26, six gray whales were found dead in and around the bay, bringing this year’s total number of whale deaths in the region to 14 — a figure not seen since the height of the Unusual Mortality Events in 2019 and 2021.
The California Academy of Sciences confirmed the deaths and noted that while necropsies have been carried out on several of the whales, the exact causes remain elusive for many. “In 2025, 14 gray whales and one minke whale have died in the greater San Francisco Bay Area region, with the cause of three of the gray whale deaths determined to be suspect or probable vessel strikes,” the academy said in a statement released Thursday.
Decomposition hampers investigation into deaths of whales
Researchers say that decomposition and the inaccessibility of some carcasses have made it difficult to determine precise causes of death. This uncertainty adds to growing concerns that something may be shifting in the marine ecosystem, altering the whales’ usual behavior patterns.
“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),” the statement added.
Gray whale sightings surge in 2025
In an unusual trend, sightings of gray whales in the bay have surged this year. Scientists have confirmed the presence of 33 individual gray whales through photo identification methods — a significant increase from just six individuals recorded throughout 2024.
This dramatic rise in whale activity in the bay is prompting researchers to investigate whether changing ocean conditions, food shortages, or increased human interaction may be influencing the animals’ migratory behavior.
Conservation efforts ramp up as more whales expected to linger
While the reason for their death is yet to be ascertained, scientists believe that the gray whales will remain in the bay for another couple of weeks before continuing their annual migration northward to Arctic feeding grounds.
In the meantime, conservation efforts are being intensified. The California Academy of Sciences is collaborating with the San Francisco Harbor Safety Committee and the U.S. Coast Guard to protect the remaining whales. Efforts include adjusting ferry routes and issuing alerts to local boaters to help them stay “whale aware” and avoid collisions.
Researchers are also closely examining whether the increasing number of whales in the bay has led to overcrowding, which could be contributing to the mortality rate. While definitive answers remain out of reach, scientists are working urgently to gather more data before the whales move on.
As the marine community waits for more insights, one thing is clear: the sudden spike in whale deaths is a troubling signal that demands both scientific scrutiny and swift policy response.
