Another gray whale has died in the Bay Area, the fourth in just eight days, and it washed ashore on Muir Beach in Marin County on Thursday morning. This spate of gray whale deaths is reminding biologists of 2019, when the whales' spring migration brought a similar high number of deaths.
The body of a female gray whale washed ashore at Crissy Field last Wednesday and had to be towed to Angel Island for a necropsy — the results of which were inconclusive, as KTVU reports. Then, a 33-foot male gray whale was found yesterday in the Bay near the Berkeley Marina and was also towed to Angel Island.
Necropsies are being performed on that whale, as well as a third that died and washed ashore south of San Francisco over the weekend.
Experts at the Marine Mammal Center say that in their experience, about half of these whale deaths occur due to human interaction — the whales either get struck by ships, or by propellers, or they got caught in netting and perish.
Regarding the female found at Crissy Field, Dr. Pádraig Duignan, the center's director of pathology, tells KTVU, "Whatever killed her did so suddenly so it's a suspicious death."
He added, "This year we’ve had these two animals and there was another one on the weekend so three animals in the San Francisco area in a very short space of time so we are concerned."
The fourth whale at Muir Beach adds to the body count — and the center says that if more deaths occur locally in the coming weeks, this will be akin to what the NOAA called a "Gray Whale Unusual Mortality Event" in 2019. That spring, there were at least nine dead whales found on local beaches in a span of a few weeks.
This morning we confirmed a fourth gray whale has washed ashore at Muir Beach. Our necropsy team will investigate both the whale found near Berkeley Marina yesterday (currently at Angel Island), and the latest whale, at Muir Beach, this afternoon. pic.twitter.com/k7Mv05XdsL— The Marine Mammal Center (@TMMC) April 8, 2021
As KPIX reports, the Marine Mammal Center is also investigating the fourth whale's death.
A number of whales have been seen in "poor body condition" in recent years due to malnutrition — possibly because a large whale population on the Pacific coast is making food finding more difficult.
The whales typically come in to the Bay in search of food, or following particular food sources — in the case of gray whales, they are known to be opportunistic eaters but they enjoy a type of tiny crustacean that can exist in the Delta and in the Bay.
Update: The whale found on Muir Beach on Thursday, a 41-foot female, was killed by a ship strike, Dr. Duignan announced on Friday. The whale had injuries to the jaw and neck vertebrae consistent with blunt force trauma due to ship strike, according to a release from the Marine Mammal Center.
"It’s alarming to respond to four dead gray whales in just over a week because it really puts into perspective the current challenges faced by this species," Dr. Duignan said.