Mussel Quarantine in Effect Statewide to Protect Public Health

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The California Department of Public Health (CDPH) has issued its annual mussel quarantine, effective from May 1 through October 31, 2025, warning recreational sport harvesters against consuming mussels gathered from the state’s ocean shorelines due to the risk of serious, potentially fatal, biotoxin poisoning.

By News Desk

The quarantine stretches from the Oregon border to the Mexican border, covering all bays, inlets, and harbors, including those in Los Angeles County. It applies only to recreationally harvested mussels and does not affect commercially sold shellfish from certified harvesters, which are subject to routine safety testing.

The seasonal restriction is implemented under California Health and Safety Code Section 131056 to prevent public exposure to naturally occurring marine toxins such as paralytic shellfish poison (PSP) and domoic acid. These toxins can build up in mussels and other bivalve shellfish like clams, oysters, and scallops. Cooking does not eliminate the toxins, making raw or cooked recreationally harvested shellfish dangerous to consume.

Early symptoms of PSP may include tingling of the lips and tongue, dizziness, slurred speech, and difficulty swallowing. In severe cases, it can lead to complete muscle paralysis and death from respiratory failure.

While mussels may still be used or sold as bait, containers must be clearly labeled: “MUSSELS FOR BAIT ONLY, UNFIT FOR HUMAN FOOD” in boldfaced type no smaller than half an inch in height.

For clams and scallops, health officials advise removing the digestive organs and dark parts, as toxins tend to concentrate in these areas. Consumers are also urged to avoid harvesting shellfish from areas exposed to sewage or chemical contamination.

The Los Angeles County Department of Public Health is working closely with CDPH to monitor shellfish toxicity levels. Anyone experiencing gastrointestinal or neurological symptoms after eating recreationally harvested shellfish should seek medical attention immediately and file a Foodborne Illness Report.

For more information or updates, call the CDPH Shellfish Hotline at 1-800-553-4133 or visit the CDPH Marine Biotoxin Quarantines and Health Advisories webpage.