San Francisco Chronicle

S.F. Bay’s first whale death of year likely due to vessel strike

The gray whale that recently washed ashore at an Alameda beach — the first reported whale death in San Francisco Bay this year — likely died due to blunt force trauma from a vessel strike, scientists said Tuesday.

A necropsy conducted Saturday by scientists at the California Academy of Sciences and the Marine Mammal Center found that the 40-foot female adult whale had “full stomach contents and injuries consistent with blunt force trauma,” according to a news release.

Scientists could not confirm an official cause of death because of the whale’s decomposed state and body position, the agencies said.

The whale death was the first to be reported in the San Francisco Bay this year.

Such fatalities increase between March and May when the animals migrate north toward Alaska, passing the Bay Area, scientists said.

Staff at the California Academy of Sciences reported the dead whale floating off Alameda’s Robert W. Crown Memorial State Beach on April 20. Two days later, the animal was towed to Angel Island for a necropsy. Scientists were unable to perform the procedure until April 27 because of extreme weather conditions and the timing of tides, scientists said.

The whale’s death also occurred after the National Oceanic and Atmospheri­c Administra­tion declared an end to an “unusual mortality event” that was in effect from 2019 to 2023 due to a high number of dead gray whales washing ashore on the western coast of the U.S., Canada and Mexico. Such fatalities were attributed to malnutriti­on, killer whale predation, entangleme­nt and vessel strikes.

“Each whale that washes up is an opportunit­y for scientists to learn more about the species and the population,” said Moe Flannery, senior collection­s manager of ornitholog­y and mammalogy at the academy, in a statement.

Flannery continued, “Although the Unusual Mortality Event (UME) investigat­ion is now closed, the science does not stop. We will continue to gain as much knowledge as possible from each whale that washes ashore in our area.”