California health officials are warning the public not to eat sport-harvested shellfish from San Diego County due to high levels of a harmful algal toxin.
The California Department of Public Health issued the advisory on Wednesday after finding "dangerous levels" of domoic acid in mussels from the area.
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The naturally occurring toxin can accumulate in seafood — including mussels, clams, scallops and oysters — and cause illness or even death in humans, according to the state agency. Cooking does not destroy domoic acid.
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Health officials say people who eat toxic seafood and get amnesic shellfish poisoning may experience symptoms 30 minutes to 24 hours afterward. Symptoms in mild cases can last several days and include vomiting, diarrhea, stomach cramps, headache and dizziness. In more serious cases, people may experience confusion, seizures, memory issues, coma and more.
Commercially sold shellfish from state-certified harvesters and dealers do not fall under this warning since they undergo regular testing for toxins, the agency said.
A CDPH map shows that as of Thursday night, Los Angeles and Santa Barbara counties are also under bivalve shellfish health advisories.
Domoic acid is one of the largest threats to marine mammals, according to the National Oceanic Atmospheric Administration. Already during this domoic acid event, SeaWorld San Diego's team has taken in dozens of marine mammals — including sea lions, pelicans and dolphins — that were poisoned with the toxin. Some have died.
In 2023, San Diego saw about a half-dozen suspected domoic acid deaths and more than a dozen other animals sickened. One SeaWorld rescuer described the 2023 event as "one of the worst outbreaks of domoic acid toxicity that I’ve seen in my history here." Last year, SeaWorld reported treating multiple animals for sickness as well.
Sickened animals are given fluids and may be prescribed anti-seizure medicine, according to Jeni Smith, the curator of the SeaWorld San Diego rescue program. The animals that do recover are returned back to the wild.
