SAN FRANCISCO – Four dead gray whales washed ashore on the beaches of the San Francisco Bay Area in the past nine days. Experts say one was hit by a ship on Friday. They tried to see how the other three died.

“It is alarming to be reacting to four dead gray whales in a little over a week as it really puts the current challenges of this species into perspective,” says Dr. Pádraig Duignan, Director of Pathology at the Marine Mammal Center.

The carcass of a 41-foot adult female gray whale landed in Crissy Field in San Francisco on March 31st. A second adult woman was found last Saturday in Moss Beach, San Mateo County. A third was found near Berkeley Marina on Wednesday and washed up in Mu County’s Muir Beach, Marin County the following day.

The whales migrate 10,000 miles in the winter off the waters of Mexico, where they mate and give birth to calves near the coast of Baja California. They return north and stay off the California coast during the spring and summer to feed on anchovies, sardines, and krill before continuing their northern migration into cool, food-rich Arctic waters.

At least 13 dead whales washed ashore in the Bay Area in 2019, and scientists said they feared this was because the animals were starving and unable to complete their annual migration from Mexico to Alaska. Biologists have observed gray whales in poor body condition during their annual migration since 2019 when the National Oceanic and Atmospheric Administration declared an “unusual mortality event”.

Malnutrition, entanglement in fishing gear and trauma from ship attacks were the leading causes of death identified by the center’s research team in recent years.

An autopsy of the whale found at Muir Beach revealed significant bruising and bleeding from the muscles around the whale’s jaw and cervical vertebrae, consistent with blunt force trauma from a ship strike. However, experts found that the whale was in good body condition due to the layer of fat and internal fat, the center said.

Experts haven’t determined how the other three whales died or whether hunger was behind their deaths.

Almost one in four gray whales migrating along the US west coast has died since the last recorded population assessment in 2015 and 2016, according to NOAA.

“Those many whales dead in a week are shocking, especially because these animals are the tip of the iceberg,” said Kristen Monsell, legal director of the Center for Biological Diversity’s Oceans program.

Experts estimate that the washed up whales account for only 10 percent of the total number of dead, while the rest of the population sinks into the sea unnoticed by humans.

Monsell said California lawmakers should require fishing gear that does not use rope and federal regulators should put mandatory speed limits on ships.

“Ship attacks and gear entanglements kill a lot of whales that we never see,” she said.

Your organization is suing the federal government for speeding speed limits on shipping lanes off California, Monsell added.