DOH Marine Biotoxin Bulletin
Beach closure listing due to red tide and other marine toxins
WDFW Olympic Region Harmful Algal Bloom (ORHAB) project

DOMOIC ACID - A major concern to washington state’s shellfish lovers

Check here for the most up-to-date domoic acid levels in razor clams on all beaches
Newsclip of domoic acid beach closure

Domoic acid, a naturally occurring toxin produced by certain types of algae, can be harmful or even fatal to humans if contaminated shellfish is consumed. The toxin was detected initially on the west coast in 1991.

Shellfish and fish can accumulate domoic acid without apparent ill effects. Research has shown that razor clams accumulate domoic acid in edible tissue and are slow to expel the toxin. In Dungeness crab, domoic acid primarily accumulates in the viscera or “butter.” Cooking or freezing affected fish or shellfish tissue does not lessen the toxicity.

Domoic acid can be fatal to people if consumed in high doses. There is no antidote for domoic acid, which causes a condition called amnesic shellfish poisoning (ASP). Symptoms include vomiting, nausea, diarrhea and abdominal cramps within 24 hours of ingestion. In severe cases, neurological symptoms develop within 48 hours and include headache, dizziness, confusion, loss of short-term memory, motor weakness, seizures, profuse respiratory secretions, cardiac arrhythmia and coma.

Since the 1991 discovery of domoic acid along the Washington coast, regular samples of razor clams are collected by Washington Department of Fish and Wildlife (WDFW) staff in cooperation with the Quinault Indian Nation. Samples are analyzed by the Washington Department of Health (DOH). The level of domoic acid determined to be unsafe for human consumption by DOH is 20 parts per million in shellfish meat tissue. This is also an accepted standard both federally and internationally.

The most recent test results for domoic acid on Washington’s beaches can be found on the department’s domoic acid reports webpage.

In 2015, WDFW curtailed spring razor clamming early due to elevated levels of domoic acid. Commercial and recreational crabbing also was closed on the Washington coast for part of the summer of 2015 due to domoic acid.

Previous outbreaks have prompted the cancellation of three entire razor clam seasons in Washington in 1991-92, 1997-98 and 2002-03. Kalaloch Beach, jointly managed by WDFW and Olympic National Park, also was closed for much of the 2004 season due to high toxin levels. In 2005, WDFW closed Long Beach for two days due to elevated toxin levels.

WDFW is actively participating in the Olympic Region Harmful Algal Bloom (ORHAB) project. See also the WDFW ORHAB web page. This monitoring project provides the data necessary to develop an “early warning” system to execute safe and efficient shellfish harvest seasons. This may help avoid massive disruptions caused by last-minute fishery closures, while still protecting the health of thousands of consumers.


An interesting side note:

One morning in the summer of 1961, hundreds of crazed birds attacked the seaside town of Capitola, California. The birds "cried like babies" as they dove into street lamps, crashed through glass windows, and attacked people on the ground. Most of the birds were sooty shearwaters, a normally non-aggressive species that feeds on small fish and comes ashore only to breed. This incident fascinated Alfred Hitchcock, who frequently vacationed in nearby Santa Cruz. He included newspaper clippings about the Capitola attack in his studio proposal for THE BIRDS, which appeared in cinemas two years later. The agent responsible for the attack is now widely thought to have been domoic acid.


For additional information:
WDFW Region 6 Office
(360) 249-4628
(ask for the razor clam management staff)