La Jolla Cove sea lion’s symptoms similar to poisoning from toxic algae turn out to be false alarm

With concerns still high about a toxic algae bloom north of San Diego, SeaWorld recently examined a young sea lion from La Jolla Cove that was feared to have domoic acid poisoning stemming from the algae. But the animal ultimately was deemed healthy and released back to the wild.

Though that sea lion did not have domoic acid toxicity, some others that have been rescued in San Diego County have.

Domoic acid is a neurotoxin produced by the rapid growth of algae called pseudo-nitzschia, according to the National Oceanic and Atmospheric Administration. Such a bloom off Ventura and Santa Barbara counties has resulted in more than 1,000 reports of sick and dead marine mammals thought to have been exposed to the algae, NOAA Fisheries stated.

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In addition to causing animal deaths, domoic acid may cause sickened sea lions to experience seizures, disorientation and hyper-reactivity and may bite as a result.

Because seizures are a symptom, SeaWorld was called when the juvenile male sea lion at La Jolla Cove was seen shaking earlier this month.

“We got reports that there was a sea lion acting lethargic and showing tremors, which some mistook for a seizure,” said Eric Otjen, vice president of zoological operations at SeaWorld San Diego. “We watched it for a while and got reports from lifeguards, but because the behavior continued throughout the day, we went and assessed him that evening.”

When SeaWorld workers observed “slight tremors,” they decided to take the sea lion in for an examination.

“We gave him a full workup the next day and found no indication of a seizure or neurological problems … so he was returned to La Jolla Cove,” Otjen said.

Still, he said, “we know [domoic acid poisoning] is down here, but in very small numbers ... nothing compared to what we were seeing in Santa Barbara.”

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The Cove sea lion was tagged so SeaWorld will have a record of his assessment should he need additional care.

The cause of the tremors is unknown, Otjen added. The sea lion may have been hurt during an encounter with another sea lion and was shaking as a response to pain, he said.

Sea lions haul out on Point La Jolla next to The Cove.

(Ashley Mackin-Solomon)

The treatment for domoic acid toxicity is “to try to flush any toxins out of their system, which means hydration,” Otjen said. “When an animal comes in, we give them a lot of subcutaneous fluids. The sooner we can get them in, the better they will be. The toxin affects the brain and can affect the heart. Once your brain is compromised, it’s not growing back.”

Indicators of domoic acid toxicity include a change of demeanor, Otjen said. “Sea lions are typically mellow animals unless you get close to them or their baby or something you are not supposed to do,” he said.

When someone files a report to SeaWorld about an animal that may need care, photos, videos, location and further details are appreciated, Otjen said.

“It’s great that people know they can call us,” he said. “It helps us and it helps the animals.”

William Gerwick, a professor at the Scripps Institution of Oceanography in La Jolla, said harmful algae blooms occur when the right combination of ocean conditions and “a bit of randomness” cause micro-algae to accumulate, or bloom.

Harmful blooms also have occurred in Southern California in 2002, 2006, 2007, 2017 and 2022, according to the Channel Islands Marine & Wildlife Institute.

Bradley Moore, a professor of marine biology, marine chemistry and geochemistry at Scripps Oceanography, is examining how domoic acid is produced and working to create a predictive model to be prepared for future toxic algae blooms. ◆