The marine diatom Pseudo-nitzschia includes numerous species, with many sometimes capable of producing the toxin domoic acid. Frequent checks of how many of these diatoms are present in Washington’s surf zone have recently found a slight uptick, but still far below the level of concern.

LONG BEACH — Reappearance of a notorious marine toxin has ended razor-clam digging just south of the Columbia River to Tillamook Head, but for now Washington beaches are unaffected.

Clam harvesting on Oregon’s North Coast was closed March 8 after tests revealed a level of 22 parts per million of domoic acid in razor clams at Clatsop Beach and Sunset Beach. In early February, domoic acid levels in the same area registered at 14 ppm. Far to the south in Oregon, some razor clams tested at Port Orford had 62 ppm as of Feb. 22.

The toxin can cause everything from upset stomachs to death, but is most closely linked with Amnesic Shellfish Poisoning, which can destroy short-term memory functions. Clam harvests aren’t permitted when the level is 20 parts per million or more.

Washington has not experienced an increase in domoic acid in clams this year, Washington Coastal Shellfish Manager Dan Ayres said Monday. In fact, Ayres said he was somewhat surprised by the news from Oregon.

“Domoic acid in levels razor clam samples have lately been a little higher on the Clatsop beaches than on any WA beach,” he said. “The most recent razor clam domoic acid test in WA was highest at Twin Harbors at 6 ppm.” Twin Harbors is the beach between the mouth of Willapa Bay and Westport.

The only small cloud on the horizon for Washington clam diggers is an uptick in numbers of the microscopic marine organisms that occasionally produce domoic acid. On March 7, the Washington Department of Fish and Wildlife’s count of surf-zone plankton levels showed a very minor increase in pseudo-nitzschia — the diatom species that can produce domoic — on Long Beach and a little more on Twin Harbors.

“The current cell count levels are much lower than levels that would cause concern,” Ayres said. “Those samples are collected twice weekly, so we will be watching them closely.”

Twin Harbors has been open to clamming many days in this season that started in October, while Long Beach has had only two digging days — not due to marine toxins, but because the clams were too small earlier in the season. At this point only two more digging days are scheduled this spring on the beach between Leadbetter Point and the mouth of the Columbia, both during the Long Beach Razor Clam Festival:

• April 20, Saturday, 7:58 a.m.; -1.1 feet

• April 21, Sunday, 8:42 a.m.; -1.2 feet

About 110,000 clams were harvested — an average of 13.2 per digger — during the most recent Feb. 17 opening on the Peninsula. Clams averaged 4.05 inches.

Oregon details

Oregon won’t reopen clamming until two consecutive tests, at least one week apart, show levels of the marine biotoxin below the state’s closure limit of 20 parts per million.

The closure of recreational and commercial clamming was announced Friday evening by the state Department of Agriculture and the state Department of Fish and Wildlife.

The Clatsop Beach and the Sunset Beach areas are home to popular and highly productive razor clam beds, which are sometimes accessed by Washington residents. The 18-mile stretch of beach accounts for 95 percent of Oregon’s razor clam harvest, according to the state.

On March 1, when the beaches first reopened to harvest after an extended closure to give small clams more time to grow, approximately 600 harvesters were on Clatsop Beach. The turnout was not too bad considering the opening was midday on a Friday with high surf and a weak low tide, said Matt Hunter, state shellfish biologist.

People were eager to dig for clams even though most of the clams they were finding were still smaller than usual, just over 3.5 inches. Clatsop Beach is usually closed seasonally from mid-July through September. Last year, the beach closed to digging in July and stayed closed through the winter.

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