The annual quarantine of all mussel species harvested by the public along the California coast begins May 1.
During the quarantine, people are advised not to collect mussels because of a high risk of marine toxins.
The quarantine applies to sport harvesting of all mussel species along the California coast, as well as in bays, harbors and estuaries, according to Dr. Ron Chapman, state health officer and director of the California Department of Public Health, and San Luis Obispo County health officer Penny Borenstein.
Commercial harvesting of mussels is not affected by the quarantine order, they wrote in a news release.
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All commercial shellfish harvesters in California, they wrote, 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.
The quarantine usually continues until Oct. 31.
“The quarantine is in place to protect the public against poisoning that can lead to severe illness, including coma and death,” said Chapman. “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 deactivate the toxins.”
The quarantine is intended to protect the public from paralytic shellfish poisoning and domoic acid poisoning, both of which are linked to natural food sources for filter-feeding animals, including bivalve shellfish.
The overwhelming majority of human cases of paralytic shellfish poisoning occur between spring and fall.
Paralytic shellfish poisoning 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, Borenstein and Chapman wrote.
In severe poisonings, complete muscular paralysis and death from asphyxiation can occur.
Symptoms of domoic acid 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.
The 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.
For updated information on quarantines and shellfish toxins, call the California Department of Public Health shellfish information line at (800) 553-4133.