The annual quarantine of all mussel species harvested by the public along the California coast begins May 1. Commercial harvesting of mussels is not affected by the quarantine order.
“The quarantine is in place to protect the public against poisoning that can lead to severe illness, including coma and death,” said California Department of Public Health (CDPH) Director Dr. Horton. “It is critical that the public honor the quarantine because there are no known antidotes to the toxins found in mussels and cooking does not reliably kill the toxins.”
The quarantine is intended to protect the public from paralytic shellfish poisoning (PSP) and domoic acid poisoning (DAP), both of which are linked to natural food sources for filter-feeding animals, including bivalve shellfish. 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 typically are 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 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 excessive bronchial secretions, difficulty breathing, confusion, disorientation, cardiovascular instability, seizures, permanent loss of short term memory, coma and death.
The quarantine usually continues from May 1 through October 31. It applies to sport harvesting of mussels along the coast, including all bays, harbors and estuaries.
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.