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(SANTA BARBARA, Calif.) — On March 27, 2025, the California Department of Public Health (CDPH) issued an Advisory “not to consume” sport / recreationally-harvested bivalve shellfish, including mussels, clams, and scallops, due to dangerous levels of domoic acid detected in mussels from Santa Barbara County. This is in addition to the Advisory CDPH issued on March 20, 2025, due to dangerous levels of paralytic shellfish poisoning toxins (PSP) detected in mussels from Santa Barbara County.
Commercially harvested shellfish in restaurants, grocery stores, or from fish markets may be safely consumed. These are not included in these advisories because commercial harvesters in California are certified by CDPH and subject to strict testing requirements to ensure that all oysters, clams, mussels and scallops entering the marketplace are free of toxins.
These advisories are designed to prevent PSP and domoic acid poisoning, also known as amnesic shellfish poisoning, in people who might otherwise consume harvested mussels that have not been tested. Both of these syndromes are from naturally occurring toxins linked to plankton consumed by shellfish, including mussels and clams. Cooking does not destroy the toxins.
Symptoms of domoic acid poisoning include vomiting, nausea, diarrhea, and abdominal cramps within 24 hours of ingestion. In severe cases, more serious symptoms develop within 48 hours and include headache, dizziness, confusion, disorientation, loss of short-term memory, muscle weakness, seizures, breathing difficulty, heart rhythm problems, coma and possibly death.
Early symptoms of PSP include tingling of the lips and tongue, which may begin within minutes of eating toxic shellfish. These symptoms are typically followed by a loss of balance, lack of muscular coordination, slurred speech and difficulty swallowing. In severe poisonings, a person may experience trouble breathing, confusion and disorientation, and medical attention should be sought immediately.
To minimize potential health risks, sport harvesters should not eat bivalve shellfish that are recreationally harvested until these advisories are lifted, and during the summer months during the annual mussel quarantine until the quarantine is lifted.
More information about PSP and domoic acid can be found on the CDPH Annual Mussel Quarantine – Frequently Asked Questions (FAQ) Web page. For updated information on quarantines and shellfish toxins, call the CDPH Biotoxin Information Line at (800) 553-4133.
