The following is courtesy of the California Department of Fish and Wildlife:
California Department of Fish and Wildlife (CDFW) Director Charlton H. Bonham has closed the recreational razor clam fishery in Del Norte County (PDF)(opens in new tab) following a recommendation from the Office of Environmental Health Hazard Assessment, which, in consultation with the California Department of Public Health, determined that the consumption of razor clams taken from Del Norte County poses a significant threat for domoic acid exposure. The fishery in this area reopened on April 29, 2021 following a five-year closure.
Pseudo-nitzschia, a naturally occurring single-celled, marine alga, produces the potent neurotoxin domoic acid under certain ocean conditions. Bivalve shellfish, like clams and mussels, accumulate the toxin without being harmed. In fact, razor clams are known to bioaccumulate domoic acid, meaning it may not clear their system until long after a bloom has abated.
Early December sampling of razor clams from Crescent Beach in Crescent City found clams exceeding the current federal action level for domoic acid of greater than or equal to 20 parts per million.
Domoic acid poisoning in humans may occur within minutes to hours after consumption of affected seafood and can result in signs and symptoms ranging from vomiting and diarrhea to permanent loss of short-term memory (Amnesic Shellfish Poisoning), coma or death. There is no way to prepare clams for consumption that will remove the toxin – cooking and freezing have no effect.
Health agencies will continue to monitor domoic acid in razor clams in Del Norte County.