Press release from the California Department of Public Health:

California Department of Public Health (CDPH) Director and State Health Officer Dr. Karen Smith today advised consumers not to eat recreationally harvested bivalve shellfish (mussels and clams) from Humboldt or Del Norte counties. Only the white meat (adductor muscle) of scallops should be consumed and the viscera (internal organs) should be discarded. 

Dangerous levels of domoic acid have been detected in mussel and razor clam samples and may be present in the other species that have not yet been tested. This toxin, also known as Amnesic Shellfish Poisoning (ASP), can cause illness or death in humans. No cases of human poisoning from domoic acid are known to have occurred in California. 

This health advisory is in addition to the annual mussel quarantine issued May 1. The annual quarantine applies to all species of mussels harvested along the California coast, as well as all bays and estuaries, and will continue through at least October 31. The July 3, 2015 warning about certain seafood caught in Monterey, Santa Cruz and Santa Barbara counties remains in effect. 

These warnings do not apply to commercially sold clams, mussels, 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. 

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. These symptoms disappear within several days. 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. 

For the most current information about shellfish poisoning and health advisories, call CDPH’s toll-free “Shellfish Information Line” at (800) 553-4133. For additional information visit CDPH’s Natural Marine Toxins: PSP and Domoic Acid Web page.