An unusually high number of disoriented marine mammals, sickened by a toxic algae bloom, is being found along Southern California’s coast, prompting concerns 2025 could be the deadliest year yet.
As an algae bloom, formed off the shores of California, including Malibu and Dockweiler Beach, is occurring for the fourth year in a row, a neurological toxin called domoic acid from the algae has already sickened dozens of sea lions and elephant seals this year alone, causing them to strand with seizures or lethargy, according to the Marine Mammal Care Center, a nonprofit rescue organization.
While algae blooms are natural phenomena, the last four years have been more intense and widespread due to warmer water temperature, the rescue group said.
What’s more concerning this year compared to 2023 is the algae bloom is starting early in February.
In 2023, the Marine Mammal Care Center had 70 sea lions in its care by July. In early March of 2025, the center is already nearly half full.
“We have room for about 120 animals, and we’re already at 50 plus,” said John Warner, CEO of the Marine Mammal Care Center. “This can add up to a real capacity issue quickly, where we run out of space, and that’s what happened in 2023.”
The animal rescue organization has been taking in up to eight sea lions or marine mammals a day in recent weeks, Warner said.
Marine biology experts also fear the algae blooms will impact seal mammal conservation. As the Channel Islands are the breeding ground for nearly 85% of all California sea lions, many females won’t be able to carry the full term of their pregnancy.
“Their bodies are just so wrecked that they will have miscarriages or aborted fetuses,” Warner explains, saying most of the female sea lions rescued this year were pregnant. “ We’re not sure what the long-term effects of this seizure activity and neurological toxin is, but we’re seeing fewer births this year on the Channel Islands.”
There is a lack of scientific data that explains what may be intensifying algae blooms, but experts fear ash from the Los Angeles wildfires, or even fire retardant used to put out the fires, may have something to do with it.
“The fire, both the brush and organic material will definitely also contribute to that,” Warner explained. “The fire retardant is a thing that we really need to understand more about in terms of what it may or may not be doing in this particular damage.”
As more people will head to the beach in the coming spring and summer, the mammal center is renewing a warning against interacting with stranded animals on the beach.
“When you have an animal that has a neurological toxin and having a seizure, you’re dooming the animal by going up to it, taking a selfie, petting it or putting your child on it,” Warner said. “The springtime especially is when these animals are breeding. Literally, it’s life and death when you interfere and stress them out.”
When spotting a stranded animal, people are encouraged to report it to the Marine Mammal Care center at 1-800-39-WHALE.
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