Domoic acid is a neurotoxin produced by Pseudo-nitzschia, a naturally occurring single-celled, marine alga, under certain ocean conditions. Bivalve shellfish, like clams and mussels, accumulate the toxin without being harmed. Razor clams are known to bioaccumulate domoic acid and it may not clear their system until long after a Pseudo-nitzschia bloom has abated.
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 that will remove the toxin – cooking and freezing have no effect.
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 clam fishery in Del Norte County can reopen safely.
While the recreational fishery in Humboldt County is currently open, razor clam sampling is ongoing. If domoic acid levels exceed federal action levels, the fishery will be closed. CDFW reminds clammers that the daily bag limit for razor clams is 20 and the first 20 clams dug must be retained regardless of size or condition. Each person is required to keep a separate container for their clams and is not allowed to commingle their take with another person when digging and transporting clams to shore.
For more information, please refer to Title 14, California Code of Regulations sections 29.20 and 29.45 for razor clam regulations that can be accessed on CDFW’s website.