Status quo in Flathead Lake
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 announce.
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 with ecosystems, boat owners and municipal water systems in the Midwest and on 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,” said Eileen Ryce, FWP’s aquatic invasive species coordinator. “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.
First discovered in the U.S. in the Great Lakes in the 1980s, zebra mussels have since spread throughout most major river drainages in the mid-western and Mid-Atlantic States. They were likely transported in boat live-wells or on hulls, where the microscopic larvae can survive for weeks. Western states sounded the alarm in 2007 when quagga mussels appeared in Nevada’s Lake Mead—the first infestation documented west of the Rockies.
The exotic mussels do not have a significant predator in Montana to keep their numbers in check, so they could reproduce and spread rapidly, especially on hard surfaces like marina docks and piers. The mussels can also block water intake pipes, clog irrigation systems, disrupt water purification and hydropower plant operations, and may impact fishery populations.