Toxic Algae Is Cause of Sea Lion Deaths

It’s more than some beachgoers can bear: the sight of a full-grown California sea lion writhing in pain, experiencing violent seizures and ultimately falling dead in a heap.

Yet it’s a fairly common sight, for the second consecutive year, on some Southland beaches, as domoic acid poisoning again has reached epidemic proportions. The natural phenomenon involves a toxic algae bloom that occurs periodically under conditions that are still largely unknown. Fish that ingest the algae apparently aren’t affected, but mammals and birds that ingest the fish are. In previous years, smaller blooms have occurred in late summer and fall.

But for the last two years, large blooms have occurred during the spring, when pregnant female sea lions are feeding voraciously. Thus, they’re the primary victims of an ailment that affects the brain, causing frequent seizures and, in most cases, death. Last year, over three months, about 1,000 sea lions perished because of domoic acid poisoning, mostly from Santa Barbara to the Mexican border.

Through May 20 this year, 155 sea lions had washed ashore dead and 164 had come ashore ill, most of which died. Additionally, 52 common dolphins had washed up dead, and five had come ashore alive, only to eventually succumb.

According to Joe Cordaro, a biologist with the National Marine Fisheries Service, sea lions that come ashore showing signs of domoic acid poisoning are put under a 48-hour watch. If they’re still alive after two days, they’re sent to one of three care centers in Santa Barbara, San Pedro and Laguna Beach.

He cautioned beachgoers not to approach the animals and suggested they call the nearest animal-control agency if a sea lion appears to be visibly ill and to have come ashore in an area where it might go unnoticed.

“The reasoning for the 48-hour watch is that if it’s not alive after two days, it probably wouldn’t have survived in a care center anyway,” Cordaro explained. “People should also realize that the sea lion population is very healthy, with about 200,000 animals. What they’re seeing is just a tiny fraction of that.”