Closed: California’s Humboldt County Razor Clam Fishery Due to Domoic Acid Exposure Risk

The California Department of Fish and Wildlife (CDFW) Director Charlton H. Bonham has closed the recreational razor clam fishery in Humboldt County after a recommendation from state health agencies that consumption of razor clams in the area poses a significant threat for domoic acid exposure. 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 the ocean conditions that caused it have abated.

In late April, sampling of razor clams from Clam Beach in Humboldt County 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.

The recreational razor clam fishery in Del Norte County remains closed due to elevated levels of domoic acid. The closure, which began in November 2023, will remain in effect until state health agencies determine razor clams no longer pose a health risk. CDFW will continue to work with the California Department of Public Health (CDPH) and Office of Environmental Health Hazard Assessment to collect, monitor and analyze razor clams to determine when the recreational razor clam fishery can be reopened safely in these areas.

For more information on any fishery closure or health advisories, please visit: www.wildlife.ca.gov/Fishing/Ocean/Health-Advisories