OLYMPIA - Razor clams are purging themselves of marine toxins ingested during a major algae bloom off the Pacific coast last year, but may not be fit for human consumption in time to allow for any razor clam digging on Washington beaches during the season that runs through the spring of 2003.
That is the conclusion of state and federal biologists who are still finding high concentrations of domoic acid in razor clams three months after soaring toxin levels prompted resource managers in Washington and Oregon to close the razor clam season until further notice.
While toxin levels have declined substantially since last October, tests conducted Dec. 29-30 at all five razor clam beaches in Washington showed concentrations of domoic acid well above 20 parts per million (ppm) - the threshold considered safe for human consumption.
"I hate to say it, but it's starting to look like we could lose the whole season," said Dan Ayres, lead coastal shellfish biologist for the Washington Department of Fish and Wildlife (WDFW). "I still haven't given up hope for a spring opening, but that's starting to look less and less likely."
In the most recent round of tests, clams taken at Kalaloch had the highest toxin levels, averaging 115 ppm. Copalis was next at 102 ppm, followed by Mocrocks at 91 ppm, Long Beach at 81 ppm and Twin Harbors at 44 ppm.
Ingesting high levels of domoic acid can cause amnesic shellfish poisoning (ASP), producing vomiting, diarrhea, abdominal cramps, dizziness and a variety of other ailments. Extreme cases can result in death, although there have been no known fatalities from ASP in Washington state.
There is no antidote for ASP, and neither cooking nor freezing the clams lessens the toxicity. The Washington Department of Health (DOH), which has the responsibility for monitoring shellfish contamination, has assured the public that all commercially harvested razor clams and other commercial shellfish currently available in the marketplace have been subjected to rigorous testing and are safe for consumption.
Twice during the past decade - in 1991-92 and again in 1998-99 - high domoic acid levels prompted WDFW to prohibit razor clam digging for the entire season to protect human health. The problem, Ayres said, is that clams retain domoic acid in their tissues long after the plankton blooms that produce it have subsided.
"At first, toxin levels seem to drop fairly quickly, but then decline much more slowly as they approach acceptable levels," said Ayres, noting that WDFW and DOH have been testing clams every two weeks.
Ayres said shellfish managers are well aware of the hardship caused by the season closure - both to recreational diggers and to coastal communities that rely on their business. Recreational clam digging can attract as many as 10,000 people to coastal beaches on a given day, generating more than $4.5 million in annual economic benefits for coastal communities.
"We share the frustration of diggers and merchants who look forward to the razor clam season," Ayres said. "Once it's safe again for people to dig razor clams, we'll let everyone know."
Updates on razor clam seasons and domoic acid levels are available on WDFW's toll-free Shellfish Rule Change Hotline at 1-866-880-5431 or on the department's website.
Although scientists have not found a way to control toxin-producing algae blooms, they are developing better methods for detecting when they have occurred. Since 1999, WDFW has been working with variety of federal, state and educational organizations through the Olympic Region Harmful Algal Bloom (ORHAB) partnership to develop an "early warning system" for marine toxin outbreaks.
The new monitoring system, which detects toxicity in coastal waters, helped to confirm indications of increasing domoic acid levels in clams at the start of the 2002-03 season.
"It was the first time that scientists had a way to confirm what they were seeing in the clams," said Vera Trainer, marine toxin research leader for NOAA-Fisheries. "Perhaps someday, resource managers will be able to use this information to structure season openings to avoid periods of high marine toxicity."