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Oyster growers in Southwest Washington drop appeal for use of controversial pesticide

Parker Miles Blohm

Oyster growers in Southwest Washington have given up on their push to use a controversial neurotoxin to control burrowing shrimp. The shrimp can turn oyster beds into quicksand that suffocates the shellfish.  The growers have dropped an appeal before the state Pollution Control Hearings Board, in favor of a settlement agreement with the state department of ecology.  

The appeal was a last-ditch effort by the Willapa Bay Grays Harbor Oyster Growers Association, after the state Department of Ecology denied their proposal to use imidacloprid last spring. An insecticide that is widely used in agriculture, imidacloprid has become increasingly controversial. It is a so-called neonicotinoid that is linked to bee colony collapse disorder and is now banned in the European Union. Amy van Saun is at attorney with the Center for Food Safety, one of the environmental groups fighting the appeal.

"It is a very highly toxic pesticide, and kills aquatic invertebrates very efficiently, which is why it's not allowed to be sprayed in or near water anywhere else in the country," she said.

The oyster growers say they were only requesting use of very small amounts on a fraction of their acreage. Still, even after revising their plans following public outcry — which included Seattle chefs who vowed not to serve any oysters raised by growers using it — the plan faced opposition. The state Department of Ecology rejected it last April, calling it "too risky."

Environmental groups are calling the settlement a victory. Larry Warnberg, a retired oyster grower, says he farmed without chemicals for 25 years. He's with the Ad-Hoc Coalition for Willapa Bay, which is an intervenor in the appeal. He wants to make sure that the pest control board that is part of the settlement includes perspectives like his.

"The emphasis shouldn't be on better ways to kill shrimp, but on better ways to farm oysters and to get along with shrimp," Warnberg said. "After all, the shrimp are a native species and the oysters are not."

Pacific Oysters -- Washington's main crop -- were first introduced around 1900 here, from Japan.  
The settlement calls for development of an alternative control plan to include chemical, as well as other approaches. It says field trials should take place in 2020 and that Ecology and the growers will together seek $650,000 from the Legislature for a broader research effort to keep native burrowing shrimp from ruining oyster harvests.  It does not rule out imidacloprid completely, but stipulates that no state funding or work group efforts would be used for further research of its use.  (Growers could theoretically apply for a new permit in future.)

The settlement agreement still needs to be approved by the state pollution control hearings board to become final. It is expected in the coming days.

Southwest Washington is one of the largest oyster growing areas in the stateand its rural economy depends heavily on aquaculture. The state is the largest producer of farmed oysters and clams in the U.S., with total revenue of farmed bivalves estimated at nearly $150 million, in 2013.

UPDATE, Oct. 22: This story has been corrected to clarify that the settlement agreement does not entirely rule out all future use of imidacloprid.  

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to