The California Department of Public Health warned consumers last Friday not to eat recreationally harvested mussels, clams, scallops or oysters from Marin County, as dangerous levels of toxins have been detected in mussels from the region. In a press release, the department said there had been no reports of related illnesses. The announcement came just three days before the state’s annual quarantine of sport-harvested mussels along the California coast, a closure designed to protect the public from paralytic shellfish poisoning and domoic acid poisoning—the two major toxic syndromes caused by harmful algal blooms found along the West Coast. The toxins affect the central nervous system and can lead to serious illness, including coma and death. The quarantine began on May 1 and typically lasts until Oct. 31, as poisonings have historically been most common between spring and fall. (Cases of poisoning are extremely rare in California.) In an email, the health department’s information officer, Ronald Owens, said the mussel quarantine has started earlier than May 1 three out of the last 10 years, but did not comment on what might cause the higher toxicity. “Don’t let your dinner party turn into tragedy by risking the consumption of sport-harvested mussels,” Dr. Karen Smith, the state’s public health officer, said in the press release. “The toxins found in shellfish can kill a person within 30 minutes. There are no known antidotes, and the toxins are not reliably destroyed by cooking.” Although crab meat is not impacted by the toxins, the health department also urged consumers to avoid consumption of viscera from crabs caught in the affected area, as crabs consume bivalves, which accumulate neurotoxins more easily, and could accumulate some of the toxin in their gut. The annual quarantine does not apply to commercially sold clams, mussels, scallops or oysters, which are certified by the department and subject to strict testing for toxicity levels.