Gray whale dies after colliding with two vessels in Northern California waters
SAUSALITO -- A gray whale that died after spending at least 75 days in the San Francisco Bay was likely killed by a combination of malnutrition and trauma caused by a collision with two maritime vessels, according to officials from the Marine Mammal Center.
The adult male whale was found dead a mile offshore last Saturday before washing up on North Beach in the Point Reyes National Seashore the next day.
A necropsy performed by a team of 11 scientists from the Marine Mammal Center and the California Academy of Sciences has revealed the 39-foot whale was emaciated at the time of death.
It also shows that the animal was likely hit by two ships or large boats in separate collisions based on its injuries. There was a large, slowly healing, older scar on its back, sea lice on the wound, multiple rib and spinal fractures under the scar.
The whale also suffered from more recent skull fractures, hemorrhaging and muscle damage to the area where the head connects to the body.
Marine Mammal Center officials said the second vessel strike resulted in damage akin to "severe whiplash" to a human involved in a car crash and was the likely cause of death.
Officials also conducted a necropsy on a second whale -- a 37-foot adult male gray whale -- discovered in Point Reyes National Seashore on Saturday, but on the north end of Agate Beach.
Scientists couldn't determine the cause of death for the second whale, which appeared to have died suddenly despite being "in excellent body condition," according to Marine Mammal Center officials.
They did find that the whale had consumed plants and invertebrates it might have "scooped up from the bottom of the Bay," where it was sighted in early May, which "supports the Center's ongoing field observations that gray whales are feeding while inside San Francisco Bay," according to the news release.
The discovery of two dead whales within hours of each other "is challenging and concerning to say the least," said Padraig Duignan, director of pathology at the Marin Headlands-based Marine Mammal Center.
The whales were the third and fourth found dead in the region this year.
According to the National Oceanic and Atmospheric Administration, the gray whale population in Alaska and along the West Coast is in the midst an "unusual mortality event" that seems to have started in 2019, during which there has been a 38 percent drop in the number of migrating whales.