Razor clam season closes early after high domoic acid levels found

Toxin levels in razor clams remain too high, forcing state shellfish managers to announce Wednesday the cancellation of the final two digs of the season.

The state Department of Fish and Wildlife canceled the digs, one that was to open Friday and another on May 22, because domoic acid levels far exceed safety thresholds. The agency had already canceled three days of a four-day dig last week due to high toxin levels.

Domoic acid is a natural toxin produced by certain types of marine algae. It can be harmful or even fatal if consumed in sufficient quantities. Dan Ayres, coastal shellfish manager for the state, said razor clams absorb the acid into their fat cells and can retain it there long after the ocean water is free of toxins.

“Based on the most recent test results that show increased levels of domoic acid, razor clams will not be safe to eat for the remainder of this month,” Ayres said.

Tests done this week showed domoic acids levels at 57 parts per million at Long Beach, 39 ppm at Twin Harbors, 41 ppm at Copalis and 34 ppm at Mocrocks. The state’s safety threshold is 20 parts per million. Just a week earlier, on April 30, test showed levels ranged from 1-3 parts per million.

“It appears the warm surf zone water temperatures likely played a role, as high as 60 degrees,” Ayres said of the sudden rise in toxin levels. “Also the presence of the harmful algal cells likely being transported from off Oregon led to the bloom of pseudo-nitzschia, a diatom that is known to produce domoic acid.”

The last time the state imposed an in-season closure was in 2005, when levels exceeded safe standards at Long Beach. In 2002-03, the entire season was canceled because domoic acids were too high.

The loss of nine days of digging will be a financial hit for coastal communities. A 2008 study shows the average digger spends $31 per day.

Ayers said the department will test acid levels when it conducts its clam population surveys this summer.