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Annual Quarantine of Sport-Harvested Mussels Begins May 1 

Date: 4/24/2012 

Number: 12-016 

Contact: Anita Gore, Heather Bourbeau (916) 440-7259 


The annual quarantine of all sport-harvested mussel species along the California coast begins May 1, 2012, announced Dr. Ron Chapman, director of the California Department of Public Health (CDPH) and state health officer. This quarantine applies to all species of mussels harvested along the California coast, as well as all bays and estuaries. 

“This quarantine is in place to protect the public against poisoning that can lead to severe illness, including coma and death,” said Dr. Chapman. “It’s critical that the public honor the quarantine because the toxins found in mussels have no known antidotes and are not reliably destroyed by cooking.” 

The quarantine is intended to protect the public from paralytic shellfish poisoning (PSP) and domoic acid poisoning (DAP), both are linked to microscopic plankton that are concentrated in filter-feeding animals, including bivalve shellfish-like mussels. The overwhelming majority of human cases of PSP illnesses occur between spring and fall. 

PSP affects the human central nervous system, producing a tingling around the mouth and fingertips within a few 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. In severe poisonings, complete muscular paralysis and death from asphyxiation can occur. 

Symptoms of DAP, also known 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. These symptoms disappear completely within several days. In severe cases, the victim may experience difficulty breathing, confusion, disorientation, cardiovascular instability, seizures, permanent loss of short‑term memory, coma and death. 

More information about the quarantine, PSP and DAP can be found on the Mussel Quarantine Frequently Asked Questions (FAQ) Web page.

The quarantine usually lasts from May 1 through October 31. Commercially harvested shellfish are not included in the annual quarantine. All commercial shellfish harvesters in California are certified by the state and subject to strict requirements to ensure that all oysters, clams and mussels entering the marketplace are free of toxins.

For updated information on quarantines and shellfish toxins, call the CDPH shellfish information line at (800) 553-4133.

Last modified on: 4/24/2013 4:07 PM