Annual Quarantine of Sport-Harvested Mussels Begins May 1​

Date: April 19, 2024
SN24-002
Contact: media@cdph.ca.gov ​

CDPH warns the public not to consume sport-harvested mussels gathered along the California coast

What You Need To Know: CDPH is implementing its annual quarantine for sport-harvested mussels gathered along the California coast beginning May 1. The quarantine does not apply to commercially sold mussels, clams, scallops, or oysters from CDPH approved sources.​

Sacramento – The California Department of Public Health (CDPH) today announced the annual quarantine of sport-harvested mussels gathered along the California coast. The quarantine begins May 1 and applies to all species of mussels that are recreationally harvested for human consumption along the California coast, including all bays and estuaries. During the quarantine, mussels may only be harvested for use as bait. The quarantine is in place to protect the public against poisoning that can lead to serious illness, including coma and death.   

The quarantine is designed to prevent paralytic shellfish poisoning (PSP) and domoic acid poisoning, also known as amnesic shellfish poisoning, in people who might otherwise consume sport-harvested mussels. Both of these syndromes are from naturally occurring toxins produced by certain phytoplankton consumed by shellfish, including mussels and clams. Cooking does not destroy the toxins.  

Historically the majority of human cases of PSP illnesses occur between spring and fall. In California, PSP is extremely rare due to the efforts put forth by CDPH to protect the public against poisoning. There have been no reported human cases of domoic acid poisoning in California.

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, complete muscular paralysis and death from asphyxiation can occur.

Symptoms of mild domoic acid poisoning 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.

This quarantine does not apply to commercially sold mussels, clams, scallops, or oysters from approved sources. State law permits only state-certified commercial shellfish harvesters or dealers to sell these products. Shellfish sold by certified harvesters and dealers are subject to frequent mandatory testing to monitor for toxins.

More information about the quarantine, 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, visit the recreational bivalve shellfish advisory interactive map or call the CDPH Biotoxin Information Line at (800) 553-4133. For additional information, please visit the CDPH Marine Biotoxin Monitoring Web page.