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CDPH Warning about Razor Clams from Del Norte County

And Sport-Harvested Bivalve Shellfish in Humboldt County

Date: November 3, 2022

Number: SN22-008


The California Department of Public Health (CDPH) is advising consumers not to eat sport-harvested razor clams from Del Norte County. CDPH also updates the advisory in effect for all bivalve shellfish in Humboldt County.  

Dangerous levels of naturally occurring domoic acid, also referred to as Amnesic Shellfish Poisoning, have been detected in razor clams in Del Norte County and mussels in Humboldt County. The naturally occurring domoic acid toxin can cause illness or death in humans. Cooking does not destroy the toxin.

For Del Norte County, this warning only applies to razor clams as they are known to concentrate and retain domoic acid toxin in their meat and tissues at higher levels and for much longer than other species of bivalve shellfish.

For Humboldt County, this notification adds a domoic acid warning to the existing warning advising consumers not to eat sport-harvested mussels, clams, or scallops from Humboldt County due to paralytic shellfish poisoning toxins.   

Symptoms of amnesic shellfish 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 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.

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

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