Southern California marine mammal hospitals have been overwhelmed by sea lions sick from the acid, which appeared in record levels off the coast of Los Angeles in April. Domoic acid poisoning has killed hundreds of the animals across Southern California this spring and thousands since a major outbreak in 2002, and has also afflicted animals in Monterey Bay, south of San Francisco.

“In over 22 years of marine mammal rescues, I’ve never seen such distress of marine mammals,” Mr. Wallerstein said. “The stress and the fright, it’s kind of shocking.” Continued...