© Patrick RobinsonHundreds of dead sea lion pups have washed ashore along the California coast in recent weeks, baffling researchers.
The phenomenon began about two weeks ago, Daniel Costa, a professor at UC Santa Cruz, told SFGATE over the phone.
"It's concerning," he said. "We've never seen anything like this."
The mystery appears to be widespread: Researchers have discovered dead pups on San Miguel Island along the Central Coast, while one of Costa's graduate students, George Colaco, counted nearly 300 deceased pups on Año Nuevo Island, off the coast near Santa Cruz. Normally, 800 pups are born on the rocky swath of land each year.
"This appears to be a rapid onset," Costa wrote in an email. "Things appeared fine a few months ago."
The cause of the deaths is still unclear; Costa said he believes that anything from disease to food scarcity could be behind it. Preliminary examinations on the carcasses showed that the sea lions were "skinny," Costa said, but more testing is needed to rule out the possibility their deaths were caused by avian flu.
Despite this grim discovery, Costa said that sea lion populations are generally booming.
After struggling against warming waters in the early 2010s, their numbers rebounded, according to a long-term study released in 2018. Last month, more than 1,000 of them took over Pier 39 in San Francisco — the highest number recorded there in almost two decades, SFGATE previously reported. In 2023, researchers were also surprised to discover that sea lions were even getting bigger.
"When we started the project," Ana Valenzuela-Toro, the lead author of the 2023 study, previously told SFGATE, "we predicted the opposite."
Reader Comments
Never mind the german computer model showed the radiation concentrating along the Ore. and Cal coasts.