The Washington State Department of Ecology has once again denied the use of the neonicotinoid pesticide imidacloprid on coastal shellfish beds, as reported in the Seattle Times.

A association of oyster growers based out of Willapa Bay in southwest Washington have been fighting since 2015 to be allowed to use imidacloprid to combat an infestation of burrowing shrimp, a native invertebrate species that is jeopardizing their harvest.

Note that the vast majority of oysters raised in Washington State are not from the region, which has only one native variety the Olympia oyster.

The oyster beds in Willapa Bay produce 25 percent of the oysters harvested in the country and are a big part of a influential, multi-million dollar shellfish industry, the largest it the country.  The native burrowing shrimp can destabilize the substrate of the tideflats where oysters are grown, causing the shellfish to sink into the mud and suffocate.

Growers first applied in 2015 to the Department of Ecology for a permit to apply this highly-toxic pesticide by helicopter to 2,000 acres of tideland   After a large, and overwhelmingly negative, public response that application was denied.  This second attempt proposed spraying just 500 acres by ground application, but the agency still concluded  “this pesticide is simply too risky and harmful to be used in Washington’s waters and estuaries.”