Non-Native Weed Threatens Northwest Clams

Japanese eelgrass has a devastating impact on yields

June 28, 2011

Japanese eelgrass smothering Willapa Bay clam beds in Sept. 2010.

The usual story of invasive species goes something like this: an exotic plant or critter hitches a ride on some incoming cargo, alarm bells go off and an eradication campaign starts.

But now, Japanese eelgrass, a non-native seaweed showing up along America’s West Coast, breaks that mold.

Willapa Bay produces more shellfish for American tables than any other inlet on the West Coast. Brian Sheldon's family has been growing clams and oysters on the tide flats here for three generations.

"These little holes here are all clams. I call this my college fund bed," he says. "I tell my kids, you go out and work that bed, because that's how you're going to college."

But, Sheldon jokes, the way things are going that's shaping up to be an inexpensive state school rather than a plush private college.

Northern Oyster Co. owner Brain Sheldon says his business has been devastated by Japanese eelgrass.

His clam beds should be bare sand but Sheldon's acreage is being overrun by a green sea grass that really belongs on the other side of the Pacific.

"In the summer, this piece of ground here will be completely covered with grass," he says. "It kinds of sits in there and holds the heat in there in the bed and it makes the clams watery and weaker."