Tests Show No Signs of Invasive Mussels in Flathead Lake

By Beacon Staff

Worries that Flathead Lake may be plagued by an unwanted and invasive species of mussels appear to be unfounded. A variety of tests, employing deep-water divers and genetic screening, have failed to turn up any evidence of the exotic mussels, according to the Montana Department of Fish, Wildlife and Parks.

“We consider the results from each of these professional investigations to be terrific news,” Eileen Ryce, FWP’s aquatic invasive species coordinator, said in a statement released Tuesday. “Still, we can’t let our guard down. We’ll continue to work with our partners at the Yellow Bay lab and others to ensure we do everything we can to keep zebra and quagga mussels from becoming established in Flathead Lake.”

In November FWP announced that divers taking samples in Woods Bay had turned up microscopic larvae similar to that of zebra and quagga mussels. State agencies and local groups have been working strenuously over the last several years to keep such mussels out of the Flathead watershed, since the non-native species reproduces rapidly, and can encrust docks, piers, irrigation pipes and hydropower plant operations that can be expensive to replace.

Prevalent along the East Coast and Midwest, the mussels have caused extensive damage to lakes and rivers there since being discovered in the 1980s. The mussels, which have no natural predators, attach themselves to boats to travel from one waterway to another, and harm fish populations by filtering nutrients out of the water.

A team of three, experienced, winter-weather divers from the U.S. Geological Survey searched likely locations in the north end of Flathead Lake in December, but found no sign of the mussels. Additionally, the U.S. Bureau of Reclamation and the California Department of Fish and Game found no sign of zebra or quagga mussel larvae in DNA samples sent by FWP.

A scientist at the University of Montana’s Yellow Bay research station also failed to turn up any evidence of the invasive species, instead determining them to be “dinoflaggelate,” a tiny plankton common to Flathead Lake.

State agencies and local groups like the Flathead Basin Commission continue to raise awareness that the best way to prevent the mussels from turning up in Flathead Lake is to ensure boaters and anglers inspect, clean and dry their boats, trailers and gear after every use. The top three aquatic invasive species test sites in Montana are in Fort Peck Lake in the northeastern corner of the state, Canyon Ferry Reservoir near Helena and Flathead Lake, because all three are popular with nonresident boaters.

For more information on zebra and quagga mussels, visit FWP’s website: www.fwp.mt.gov.

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