Warning issued for recreational mussels along California coast

Los Angeles County public health officials are urging people not to eat recreationally harvested mussels from the California coast due to an increase in naturally occurring toxins that can cause serious illness.

This does not apply to commercial shellfish from approved sources.

A mussel quarantine order will be in effect from May 1 through Oct. 31, 2026, covering all species of mussels gathered by recreational sport harvesters along California’s ocean shoreline, from the Oregon border to the Mexican border. The order also includes all bays, inlets and harbors in Los Angeles County.

During the quarantine period, officials say mussels should not be consumed by humans.

Health officials warn that during the warmer months, mussels can concentrate naturally occurring toxins that are highly poisonous to humans. These include paralytic shellfish poisoning (PSP) toxins and domoic acid, which can be found in bivalve shellfish such as mussels, clams, oysters and scallops.

Cooking does not destroy the toxins, officials said.

The annual quarantine is required to prevent human illness and works alongside year-round surveillance, shellfish advisories and commercial closures, when necessary.

Under state law, the sale of any bivalve shellfish for human consumption is prohibited unless it comes from a state-certified shellfish harvester or dealer. Certified harvesters and dealers are subject to frequent, mandatory testing to ensure products are safe to eat.

Symptoms of PSP:

• Early symptoms include tingling and numbness of the lips and tongue, which may begin within minutes to several hours after eating toxic shellfish
• These symptoms are often followed by a loss of balance, lack of muscular coordination, slurred speech, and difficulty swallowing
• Complete muscular paralysis and death from asphyxiation can occur in severe cases without proper medical care

Symptoms of domoic acid poisoning (aka amnesic shellfish poisoning):

• Symptoms can occur within 30 minutes to 24 hours after eating toxic seafood
• Mild cases include symptoms like vomiting, diarrhea, abdominal cramps, headache and dizziness
• Severe cases include trouble breathing, confusion, disorientation, cardiovascular instability, seizures, excessive bronchial secretions, permanent loss of short-term memory, coma or death

Treatment is supportive, including mechanical ventilation, as there is no known antidote to the toxin, officials said. Symtoms tend to resolve completely within a few days.

If you’re experiencing PSP or domoic acid symptoms, seek immediate medical attention.

Anyone experiencing gastrointestinal or neurological symptoms after eating mussels taken for human consumption by recreational sport harvesters from California’s shore is encouraged to submit a Foodborne Illness Report and seek medical care.

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