YELLOW BAY — Deep-water divers, genetic scrutiny, and rigorous examinations with high powered microscopes have failed to turn up any evidence of exotic mussels in Flathead Lake near Woods Bay, Montana Fish, Wildlife & Parks officials said last week.

FWP reported last November that scientific results were conflicting on whether or not routine plankton samples from Flathead Lake also contained tiny zebra or quagga mussel larvae, two damaging, invasive species that have wreaked havoc on ecosystems, boat owners and municipal water systems in the Midwest and along the East Coast.

The questioned discovery of exotic mussels prompted FWP to work with experienced winter-weather divers from the U. S. Geological Survey who could identify mussels. A team of three divers searched several likely locations at the north end of Flathead Lake in December, but found no sign of the mussels. In addition, FWP sent samples for DNA examination to the experienced labs at the U.S. Bureau of Reclamation and the California Department of Fish and Game, and again no evidence of zebra mussel or quagga mussel larvae was found.

Most recently, a scientist at the University of Montana’s Biological Station at Yellow Bay examined and studied images of the suspected organisms and determined them to be a “dinoflaggelate,” or a tiny plankton common to Flathead Lake.

“We consider the results from each of these professional investigations to be terrific news,” Eileen Ryce, FWP’s aquatic invasive species coordinator said. “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.”

Managers say that Montana’s best defense against invasive species is for boaters and anglers to inspect, clean, and dry their boats, trailers, and fishing gear after each use.