Asian clams discovered in Hope

HOPE — The annual winter drawdown of Lake Pend Oreille revealed that a new aquatic invasive species has gained a toehold in Bonner County.

Asian clams were discovered on about 150 feet of shoreline at Ellisport Bay. The small, light-colored bivalves have been in the country since the 1930s and in Idaho’s Snake River since the 1950s, according to the U.S. Geological Survey.

“But this is the first real population that’s been discovered up in this region,” said Tom Woolf, a program manager for the Idaho State Department of Agriculture’s invasive species bureau.

The clams are typically spread by the discharge of ballast water, bilge water or the contents of live wells.

They can also become embedded in mud stuck to watercraft trailers.

“The proximity where we found these things would suggest that because it is right in a marina facility,” Woolf said.

There are no reports of Asian claims being present elsewhere in the Pend Oreille system.

Dive teams from the Bonner and Boundary county sheriff’s offices will be working with ISDA on Monday at Ellisport Bay to gauge the distribution of the invasive bivalve.

Although the clams can grow to the size of a silver dollar, the ones found at Ellisport Bay are about the size of a nickel, according to Deputy Phil Stella, who coordinates Bonner County’s dive team.

Asian clams are not quite as prolific as dreaded quagga and zebra mussels. The mud-dwelling clams reproduce quickly, but they don’t adhere to the multitude of surfaces zebra and quagga do, said Woolf.

“Asian clam is not desirable, but their impacts aren’t nearly as significant as what zebra and quagga’s could be,” Woolf said.

Asian clams are filter feeders that swindle food from native species and prodigious excreters of highly concentrated stores of nutrients.

Woolf said Asian clam waste is blamed for algal blooms in New York state’s Lake George.

Resource managers at Lake George and Lake Tahoe have been using gas-impermeable rubber mats with mixed results.

“They basically just smother the clams in the sediment,” said Woolf.

Asian clams, also known as golden freshwater clams, are found in 38 states and the District of Columbia. They were first detected in the U.S. in 1938 on near the mouth of the Columbia River in Washington state, a USGS dossier said.

It’s believed the clams first entered the U.S. as a food item favored by Chinese immigrants or through the importation of Giant Pacific oyster from Asia.