CDPH Advises Consumers Not to Eat Sport-Harvested Bivalve Shellfish from Humboldt County
September 9, 2025
SN25-021
What You Need to Know: CDPH warns consumers not to eat recreationally harvested mussels, clams, scallops or oysters from Humboldt County due to dangerous levels of domoic acid detected in mussels from Humboldt County.
SACRAMENTO – The California Department of Public Health (CDPH) is advising consumers not to eat sport-harvested mussels, clams, scallops, or oysters from Humboldt County. This warning does not apply to commercially sold mussels, clams, scallops, and oysters from approved sources.
Dangerous levels of domoic acid, also referred to as amnesic shellfish poisoning, have been detected in mussels from Humboldt County. The naturally occurring domoic acid can cause illness or death in humans. Cooking does not destroy the toxin.
This shellfish safety notification is in addition to the annual mussel quarantine. The annual quarantine prohibits the sport-harvest of mussels for human consumption and applies to all species of mussels harvested for human consumption along the California coast, as well as all bays and estuaries, and will continue through at least October 31.
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.
This warning does not apply to commercially sold mussels, clams, scallops, and 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 biotoxins.
You can get the most current information on shellfish advisories and quarantines by calling CDPH's toll-free Shellfish Information Line at (800) 553-4133 or viewing the recreational bivalve shellfish advisory interactive map. For additional information, please visit the CDPH Marine Biotoxin Monitoring web page.