Consumers Advised Not to Eat Recreationally Harvested Mussels from California Coast

The public is advised of a California Department of Public Health (CDPH) mussel quarantine order effective May 1 through October 31, 2026. During the quarantine, all species of mussels gathered by recreational sport harvesters from California’s ocean shore should not be consumed by humans. The quarantine area extends from the Oregon border to the Mexican border, including all bays, inlets, and harbors in Los Angeles County. The Los Angeles County Department of Public Health conducts daily syndromic surveillance to identify cases of illness due to ingestion of mussels and other bivalent shellfish and works with CDPH by collecting shellfish for testing.

This quarantine is to protect and preserve public health under the California Health and Safety Code Section 131056. During the quarantine season, mussels may concentrate naturally occurring toxins that are highly poisonous to humans including paralytic shellfish poison (PSP) and domoic acid biotoxins in bivalve shellfish (mussels, clams, oysters, and scallops). Shellfish toxin levels do not have predictable cycles and can increase rapidly. Prevention of human illnesses requires the annual quarantine, combined with year-round surveillance, public education, shellfish advisories and commercial closures as needed. Cooking does not destroy the toxins.

This advisory does not apply to commercial shellfish from approved sources.

State law prohibits the sale or offering for sale for human consumption of any bivalve (two-shelled) shellfish, except by a State-certified commercial shellfish harvester or dealer. Shellfish sold by certified harvesters or dealers are subject to frequent mandatory testing and are not subject to this quarantine.

Mussels may be used or sold for use as bait when displayed and sold in containers labeled in boldfaced type letters at least one-half inch in height as follows: MUSSELS FOR BAIT ONLY, UNFIT FOR HUMAN FOOD.

Symptoms and Treatment

Early symptoms of paralytic shellfish poison (PSP) include tingling and numbness of the lips and tongue, which may begin within minutes to a few hours after eating toxic shellfish. These symptoms are typically 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, also referred to as amnesic shellfish poisoning, can occur within 30 minutes to 24 hours after eating toxic seafood. In mild cases, symptoms may include vomiting, diarrhea, abdominal cramps, headache and dizziness. In severe cases, the victim may experience 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 for severe cases, since there is no known antidote to the toxin. Symptoms tend to resolve completely within a few days. People experiencing PSP or domoic acid symptoms should seek immediate medical attention.

Clams and Scallops

People consuming clams or scallops are warned to remove and discard the digestive organs or viscera and any other dark parts. Only the white meat of clams and scallops should be prepared for human consumption. Also, bivalve shellfish should not be collected for food from any area subject to sewage or chemical contamination.

If you or a family member experiences gastrointestinal or neurological symptoms after eating mussels taken for human consumption by recreational sport harvesters from California’s ocean shore, please submit a Foodborne Illness Report and seek medical care. For additional information call the Shellfish Hotline at 1-800-553-4133 or online at the CDPH Marine Biotoxin Quarantines and Health Advisories.

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