The California Department of Fish and Wildlife (CDFW) Director Charlton H. Bonham has closed the recreational razor clam fishery in Humboldt County following a recommendation from state health agencies determining 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.

Sampling of razor clams from Clam Beach in Humboldt County in early April (PDF) 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 clam fishery in Del Norte County is also closed at this time. 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.

To get the latest information on current fishing season closures related to domoic acid, please call CDFW’s Domoic Acid Fishery Closure Information Line at (831) 649-2883.

For the latest consumption warnings, please call CDPH’s Biotoxin information Line at (510) 412-4643 or toll-free at (800) 553-4133.