Oregon is closed to razor clam digging for the rest of the month, and researchers believe such closures could become a regular occurrence as they see the number of harmful algal blooms recorded in recent years increase.

Roughly 95 percent of razor clam digging in the state occurs on the relatively flat Clatsop County beaches between the Columbia River and Seaside, where razor clam populations are the most stable. A record 2.1 million razor clams were harvested in the county last year.

This season, though, the state’s beaches have remained closed to diggers. Test results this week show levels of the marine toxin domoic acid remain high in razor clams and, in some cases, have actually gone up.

The Oregon Department of Fish and Wildlife, with the state Department of Agriculture, must now cycle through another two sample periods. Only if both of those periods result in “clean” razor clams will the state consider opening the beaches to diggers.

“So pretty much May is gone,” said Matt Hunter, a Department of Fish and Wildlife shellfish and phytoplankton project leader based in Astoria.

For the past 20 years, since domoic acid was first documented on the West Coast in 1991, the blooms have followed somewhat predictable patterns.

In Oregon and Washington state, they would appear in the fall, sometimes the spring, and then disappear again after a few weeks.

“Then, in 2015,” said Kathi Lefebvre, a research biologist with NOAA Fisheries’ Northwest Fisheries Science Center, “Bam!”

The largest harmful algal bloom ever recorded struck the West Coast.

This bloom shut down more than razor clam digs.

By mid-August, the Washington Department of Fish and Wildlife had closed 90 miles of the state’s 157-mile-long outer coast to commercial and recreational crabbing. Millions of dollars were lost.

Domoic acid, a toxin produced by a certain type of phytoplankton, is known to cause severe brain damage and even death in sea lions and bird species that consume contaminated prey — and can do the same to humans. During the big bloom in 2015, scientists recorded the deaths of 30 large whales in the western Gulf of Alaska. It is suspected, though not certain, that domoic acid played a role in these deaths.

“The whole entire system was shaken,” Lefebvre said.

Other blooms have come and gone since, even while the effects of that big bloom continue to ripple through the ecosystem.

Besides forcing state fishery managers to cancel several recreational clam dig openers in the past two years, domoic acid has also delayed the start of two commercial Dungeness crab seasons.

Earlier this year, researchers with the National Oceanic and Atmospheric Administration and other groups linked the massive bloom to ocean conditions, specifically the higher temperatures recorded at the time. Warm water creates a climate in which pathogens and diseases flourish, further complicating the picture.

Lefebvre looks at how toxins such as domoic acid move through the food web, how they accumulate in species such as razor clams and, then, where this hits marine mammals and human health. As she and other researchers continue to see high levels of toxin persist in the water and in marine animals, they worry what it could mean for human populations.

Oregon and Washington’s safety precautions are stringent and a 20 parts per million threshold established in both states for domoic acid levels in razor clams is conservative, an abundance of caution, say fishery managers.

Oregon recently regained funding to test water and see what phytoplankton is present, testing that helps fishery managers get a vague sense of what might be coming down the road. Washington has had this testing for years but Oregon has only had it sporadically. Both states’ fish and wildlife departments test tissue samples in razor clams and crabs, as do the state departments that determine whether or not to close down razor clam digs: the Department of Agriculture in Oregon, and the Department of Health in Washington.

Instead, Lefebvre worries about people who harvest for themselves, and who may have traditional spots that don’t fall within areas monitored regularly by the states.

“People need to be aware of more risk, even with traditional harvesting practices, as the food web is contaminated more often,” she said. “Maybe their practices have been safe for many years. Things are changing.”

Washington has had a bit more luck than Oregon this year, though not much.

Digs early in the season went ahead more or less as scheduled in Washington, but by March and April, fishery managers had canceled several digs due to high levels of domoic acid. Long Beach, a popular destination for diggers, didn’t open at all until April 12.

Then, at the end of April, the Washington Department of Fish and Wildlife gave razor clam diggers a six-day opening at several beaches, and increased the daily limit from 15 to 25 clams at Long Beach.

“It really was some very extraordinary circumstances,” said Department of Fish and Wildlife coastal shellfish manager Dan Ayres about the limit increase in Long Beach. Because nobody had been digging clams, there was an older population of very large clams available and Ayres said the department recognized that “the community had been deprived of the benefit of having razor clam diggers visit.”

They couldn’t offer more days, but they could offer more clams.

Then, on May 4, the Department of Fish and Wildlife closed two beaches — Long Beach and Twin Harbors — for the rest of the month when domoic acid levels shot back up again. Another beach closed after the state hit its quota there. On Tuesday, the state announced that all of Washington’s beaches were closed to razor clam digging for the rest of the month, with levels of domoic acid high up and down the coast.

The reason Washington was able to open at all while Oregon remained closed is thanks in large part to the Columbia River, which can act as a sort of barrier between the states, Hunter said.

Phytoplankton drifts. Clumps of it may be in one spot and nowhere to be found a few miles away. It may be present and not producing domoic acid. Even with the barrier created by the Columbia River, it all comes down to what’s in the water.

And what’s in the water is complicated.

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