Toxin levels finally drop in razor clams

A razor clam on the beach near Fort Stevens State Park.

Levels of a harmful marine toxin dropped in razor clam populations this summer after remaining above state thresholds for most of the season, but fishery managers aren’t sure what September could bring.

In the past two weeks, Washington state has seen levels of pseudo-nitzschia, the diatom that can produce domoic acid, rise, fall and rise again in the ocean. Even as levels of the toxin have gone down, Oregon fishery managers recorded domoic acid in mussels in July. Matt Hunter, shellfish project leader with the Oregon Department of Fish and Wildlife, said the discovery was a “red flag” since these shellfish don’t hold on to the toxin the way razor clams do.

The data collected from the mussels is concerning, but the species of pseudo-nitzschia that produces domoic acid can be present in the water and not producing any toxins.

“I’m not ready to say, ‘Hey, panic!’ but certainly we’re going to keep watching,” said Dan Ayres, coastal shellfish manager with the Washington Department of Fish and Wildlife. “We’ll just continue to look at it and hope for the best,” he added.

Unsafe levels of domoic acid in razor clams shut down digs in both states this season. Oregon, in fact, has yet to open for a single dig, and Washington only opened sporadically.

The naturally-occurring marine toxin has become a familiar dilemma in recent years, plaguing both recreational razor clam digs and commercial Dungeness crabbing efforts.

And there are other concerns. While Ayres and state biologists are seeing an explosion of young razor clams farther north now, Long Beach’s populations are unusually low.

“We’re not seeing a lot of juvenile razor clams that should be there at Long Beach,” Ayres said. When that area opened briefly this spring, the state allowed a higher than normal per-person take of the clams, reasoning that it was the first chance people had had all year to dig for clams. Even then, diggers only harvested a fraction of what the state allowed overall, and, in general, harvest does not appear to drastically impact razor clam populations, Ayres said.

“It’s a big puzzle,” he said.

He has several theories, but razor clam populations can fluctuate from season to season.

Though dangerous to humans and marine mammals, domoic acid doesn’t appear to affect razor clams, said Mitch Vance, a shellfish project leader based out of Newport with the Oregon Department of Fish and Wildlife. Other factors like food availability, how densely packed clams are in an area and how many young clams are produced each year are much more important factors.

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