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News / Sports / Outdoors

Shellfish harvest shut down

Decision comes after several people sickened by PSP outbreak

By Terry Otto, Columbian freelance outdoors writer
Published: June 15, 2024, 6:10am
3 Photos
A mess of razor clams that were harvested during a clam dig in Oregon in late May. Managers do not know how long it will take for clams and mussels to clean out after absorbing the biotoxins.
A mess of razor clams that were harvested during a clam dig in Oregon in late May. Managers do not know how long it will take for clams and mussels to clean out after absorbing the biotoxins. (Terry Otto For The Columbian) Photo Gallery

The Washington Department of Health issued a biotoxin notice Tuesday closing all recreational bivalve harvesting along the Washington coast.

An outbreak of Paralytic Shellfish Poisoning (PSP) sickened several people in Oregon, and has been responsible for the closing of all recreational shellfish harvesting along both the Oregon and Washington coasts. These closures include all mussels, bay clams, razor clams, and oysters.

The closure affects public beaches in Willapa Bay and Grays Harbor that are usually open year-round for clam, oyster, and mussel harvesting under Washington Department of Fish and Wildlife (WDFW)’s recreational shellfish management. Crabs and shrimp are not affected by the closure.

Also, razor clamming has ended for the summer, and will not be reopened until next fall. However, that will depend on the WDFW testing the clams to make sure they are safe to eat prior to allowing a dig to take place.

There have also been closures of commercial harvests of clams and oysters along both states’ coasts, but commercial harvest has been resumed in Willapa Bay, and other Washington areas, although under intense biotoxin testing.

The harvesting of crabs within the usual seasons is still open, but managers are advising the public to remove the “butter”, which are the guts of the crab before cooking.

According to Matt Hunter, the shellfish project leader for the state of Oregon, the outbreak was caused by a heavy bloom of a species of phytoplankton.

“Paralytic Shellfish Poisoning is caused by a neurotoxin produced by a dinoflagellate called Alexandria,” Hunter said. “It’s a phytoplankton, and it’s a little different from the one that causes domoic acid.”

The PSP biotoxin affects the nervous system and paralyzes muscles. High levels of PSP can cause severe illness and death. In this recent outbreak, over 30 people in Oregon have been sickened.

Unlike domoic acid, which has become the major biotoxin affecting shellfish harvests only in the last 50 years, PSP has always been around.

Hunter notes that in the 1600’s, Captain George Vancouver’s crew were sickened by PSP after they harvested mussels along Vancouver Island.

“Native Americans up in Alaska and along the west coast have commonly had issues with PSP,” he added.

Hunter explained that when the conditions are right, species of phytoplankton will “bloom”, or explode in numbers, and they become the dominant food for bivalves. This most recent bloom has eclipsed the other blooms of Alexandria in recent history, with levels of biotoxins much higher than in any of the incidents in the past.

The conditions needed for a bloom are climate related, and ocean related, and includes a combination of the right temperatures, and nutrients. Recent weather has produced an increase in upwelling along the coast, and that brings a heavy load of nutrients into coastal waters. This upwelling, combined with the right water temperature, produced perfect conditions that allowed this massive bloom to happen.

In Washington and in Oregon, species such as bay clams are almost always open year-round. However, the evergreen state manages its razor clam fisheries in a much more conservative manner than Oregon, with short seasonal openers clustered around the best tides. In Oregon, the razor clam beaches are always kept open, except during the conservation closure from July 15 through Sept. 15. This is done to allow the clams to take part in the spawn without interruption.

For razor clam enthusiasts in Washington, the open season is already closed, but many clammers from north of the Columbia River often take part in Oregon’s late seasons. The daytime tides in May and June are excellent for harvesting razors, and the weather tends to cooperate during these months.

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When asked how long these closures may remain in place, Hunter admitted that the question is a tough one to answer. First, some bivalves will clear out faster, while others will need more time.

“These things can be short-lived,” said Hunter, “The blooms are short-lived, but then you end up with these accumulations in shellfish which can take weeks to months or even longer than that to clear out.”

He further explained how the different species clean out at different speeds.

For instance, mussels accumulate the toxins really quickly, and they get rid of it quickly as well.

“Bay clams and oysters don’t accumulate it as quick as the mussels,” said Hunter, “but they don’t clean out as quick. Razor clams accumulate it slower than other species, but then they take longer to clean out.”

Razor clams only clean out when they grow, or lose body mass quickly, which happens when they spawn. Hunter reports they can lose 30 percent of their body mass during the spawn.

“If you spawn and lose your body weight, and then regain body weight quickly then you are going to lose the toxins faster,” Hunter added.

It remains to be seen whether this summer’s spawn will clear the clams of toxins fast enough to allow for the resumption of razor clam harvests, either before the conservation closure in Oregon, or before the fall clamming tides.

Further details regarding seasonal closures and regulations for Washington beaches are available on the Washington Fishing Regulations web page. Current closure information is available on the Washington Shellfish Safety Map or by calling the biotoxin/red tide hotline at 1-800-562-5632.

Additional information regarding marine biotoxins and related illnesses is available on DOH’s website.

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Columbian freelance outdoors writer