Dangerous levels of the nerve toxin domoic acid have been detected in some of these species and may be present in the other species not yet tested. Domoic acid is a naturally occurring toxin that can cause illness or death in humans.
This advisory is in addition to the current quarantine on the sport-harvesting of mussels along the entire California coastline that took effect May 1, 2012 and does not apply to commercially sold clams, mussels, scallops, or oysters from approved sources. State law only permits state-certified commercial shellfish harvesters or dealers to sell these products. Shellfish sold by certified harvesters and dealers are subject to frequent mandatory testing.
No cases of human poisoning from domoic acid are known to have occurred in California.
Symptoms of 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 difficulty breathing, confusion, disorientation, cardiovascular instability, seizures, excessive bronchial secretions, permanent loss of short term memory, coma, and death. CDPH advises consumers that seafood containing domoic acid poses a significant danger to many species and should not be fed to pets or other animals.
The CDPH website has additional information regarding domoic acid. To receive updated information about shellfish poisoning and quarantines, call CDPH toll-free “Shellfish Information Line” at (800) 553-4133.