Four dead gray whales have washed up on the beaches of the San Francisco Bay Area over the past nine days, with experts saying Friday one was hit by a ship. They tried to determine how the other three died.
“It is alarming to respond to four dead gray whales in just over a week, as it really puts the current challenges facing this species into perspective,” said Dr Padraig Duignan, Director of Pathology at the Navy. Mammal Center.
The carcass of a 41-foot (12.5-meter) adult female gray whale landed at Crissy Field in San Francisco on March 31. A second adult woman was found last Saturday in Moss Beach, San Mateo province. A third was found floating near Berkeley Marina on Wednesday, and the next day one washed up on Muir Beach in Marin Province.
The whales migrate 16,090 km to the winter of Mexico’s waters, where they mate calves and are born near the coast of Baja California. They head back north and stay off the coast of California in the spring and summer to feed on anchovies, sardines and krill before continuing their northern trek to cool, food-rich Arctic waters.
In 2019, at least 13 dead whales washed ashore in the Bay and scientists said they were afraid the animals would starve and could not complete their annual migration from Mexico to Alaska. Biologists have observed gray whales in poor physical condition during their annual migration since 2019, when an ‘unusual death event’ was declared by the National Oceanic and Atmospheric Administration (NOAA).
Malnutrition, entanglement in fishing gear and trauma due to attacks on the ship have been the most common causes of death found by the center’s research team in recent years.
An autopsy of the whale found at Muir Beach showed severe bruising and bleeding to muscles around the jaw and neck vertebrae of the whale, consistent with the traumatic trauma resulting from the shipwreck. According to experts, the whale is in good body condition based on the lower layer and the internal fat levels, the center said.
Experts have not yet determined how the other three whales died and whether famine was behind their deaths.
Nearly one in four gray whales migrating along the U.S. west coast has died since the last recorded population survey in 2015 and 2016, according to NOAA.
“These very dead whales in a week are shocking, especially since 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-out whales represent only 10% of the total number of dead, while the rest sink unnoticed by humans into the sea.
Monsell said lawmakers in California need fishing gear that does not use rope, and that federal regulators should set mandatory speed limits for ships.
“Ship attacks and entanglement of fishing gear kill many whales that we never see,” she said.
Her organization has sued the federal government to get speed limits on waterways outside California, Monsell added.