Gray whale dies after collision with two boats off Northern California

SAUSALITO — A gray whale that died after spending at least 75 days in San Francisco Bay likely died of malnutrition and trauma from a collision with two ships at sea, according to Marine Mammal Center officials.

The adult male whale was found dead about a mile offshore on Saturday and washed up on North Beach on the Point Reyes National Seashore the next day.

An autopsy conducted by a team of 11 scientists from the Marine Mammal Center and the California Academy of Sciences revealed that the 39-foot whale was emaciated at the time of death.

It also suggests that, depending on its injuries, the animal was likely hit by two boats or a large vessel in separate collisions. It had a large, slowly healing, older scar with sea lice on its back and multiple broken ribs and spine beneath the scar.

The whale also suffered a recent skull fracture, bleeding and muscle damage in the area where the head connects to the body.

Officials at the Marine Mammal Center said the second boat strike caused injuries similar to “severe whiplash” to a person involved in the crash, which likely contributed to the death.

Officials also performed a necropsy on a second whale — a 37-foot adult male gray — that was spotted Saturday on the Point Reyes National Seashore, but at the northern end of Agate Beach.

Scientists were unable to determine the cause of death of the second whale, which appeared to have died suddenly, although it was “in good health,” according to Marine Mammal Center officials.

They did find that the whale had been eating plants and invertebrates it may have “scooped from the bottom of the bay” in early May, which “supports the center’s ongoing field observations that gray whales are Foraging Cove in San Francisco,” according to the release.

Finding two dead whales within hours was “challenging and worrying, to say the least,” said Padraig Duignan, director of pathology at the Marine Mammal Center in the Marin Headlands.

The whales are the third and fourth dead found in the area this year.

Gray whale populations in Alaska and the West Coast are in the midst of an “exceptional mortality event” that appears to have started in 2019, during which time the number of migratory whales declined by 38%, according to NOAA.