Four dead whales washed off the shores of the San Francisco Bay Area nine days ago, experts said on Friday. They were trying to find out how the other three died.
“It is frightening to turn four dead whales endlessly in more than a week because it numbers the current challenges facing the species,” said Dr. Pádraig Duignan, Director of Pathology at The Marine Mammal Center.
The body of a 41-year-old female whale arrived at San Francisco's Crissy Field on March 31. A second adult female was found last Saturday in Moss Beach in San Mateo County. A third was found floating Wednesday near Berkeley Marina and the next day another bathed in Mair County in Mair Beach.
Whales travel 6,000 miles [10,000 km] in the winter from the waters of Mexico, where they mate and breed calves near the coast of Baja California. They head back north and live off the California coast in spring and summer to feed on anchovies, sardines and krill before continuing their migration north into the cool, food-rich waters of the Arctic.
By 2019, at least 13 dead whales have been washed ashore in the Bay Area and scientists say they fear it is because the animals are starving and unable to complete their annual migration from Mexico to Alaska. Biologists have observed gray whales in critical condition during their annual migration from 2019, when a “rare death event” was declared by the National Oceanic and Atmospheric Administration.
Malnutrition, fishing traps, and casualties from ship strikes have been the most common causes of death by a team of researchers at the institute over the years.
A whale necropsy found in Mair Beach revealed significant damage and bleeding to the muscles around the whale's jaw and spinal cord accompanied by severe trauma due to the shipping strike. But experts have noted that whales are in good health based on a layer of fat and internal fat levels, the center said.
Experts have not yet determined how the other three whales died or whether the famine had caused their deaths.
About one in five gray whales migrate along the U.S. coast. West has died since the last humanitarian test in 2015 and 2016, according to NOAA.
“The large number of dead whales a week is appalling, especially since these animals are just the beginning of the ice,” said Kristen Monsell, legal director of the Center for Biological Diversity’s Oceans program.
Experts estimate that washed whales account for only 10 percent of the total death toll, while others die at sea without being seen by humans.
Monsell said California lawmakers need to require wireless fishing equipment, and state regulators should set speed limits for vessels.
"Shipping and fishing strikes are catching more whales we have never seen before," he said.
His organization is suing the state government for speed limits on shipping routes to California, Monsell added.