Skip Navigation LinksSN23-001

office of communications

Contact :

Office of Communications

CDPH Lifts Warning about Certain Shellfish from Humboldt County except Razor Clams

Date: January 9, 2023
Number: SN23-001

The California Department of Public Health (CDPH) has lifted the shellfish safety notification today related to sport-harvested mussels, scallops, and most types of clams in Humboldt County. An advisory for razor clams in Humboldt County remains in effect.


The shellfish safety notification was issued due to dangerous levels of naturally occurring paralytic shellfish poisoning (PSP) toxins and domoic acid, also referred to as amnesic shellfish poisoning, that can cause illness or death. Recent testing of mussels and oysters shows PSP toxins and domoic acid have decreased to safe or undetectable levels for bivalve shellfish, except razor clams, in this area.


A warning against eating sport-harvested razor clams from Humboldt County remains in effect as razor clams are a high risk for long-term elevated levels of domoic acid. Razor clams are known to retain domoic acid toxin in their meat and tissues much longer than other species of bivalve shellfish. CDPH has not received recent samples of razor clams from this area, but the recent elevated concentrations in Del Norte County razor clams indicate high domoic acid risk.


This notification 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.


PSP toxins affect the central nervous system, producing a tingling around the mouth and fingertips within a few minutes to a few hours after eating toxic shellfish. These symptoms are typically followed by loss of balance, lack of muscular coordination, slurred speech and difficulty swallowing. In severe poisonings, complete muscular paralysis and death from asphyxiation can occur.


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. No cases of human amnesic shellfish poisoning from domoic acid are known to have occurred from shellfish harvested in California.


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

Page Last Updated :