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Water samples positive for invasive mussel larvae in Tiber Reservoir


Wednesday, November 09, 2016

Attachment for 'Stop Aquatic Hitchers--Inspect, Clean And Dry Boats And Fishing Gear' (Public News Article #9349)

Zebra Mussels

Fisheries Biologists checking for adult mussels

Fisheries biologists checking for adult mussels

Water samples from Tiber Reservoir east of Shelby have tested positive for the larvae of aquatic invasive mussels, with similar tests from Canyon Ferry Reservoir near Helena showing “suspect” or inconclusive results, according to officials at Montana Fish, Wildlife and Parks .

FWP, along with other state and federal agencies and the Montana Invasive Species Advisory Council (MISAC), are now working to determine whether adult mussels are present in Tiber Reservoir and to get further test results on Canyon Ferry.

“This is the first positive test in Montana for the larvae of quagga or zebra mussels,” said Eileen Ryce, FWP fisheries division administrator. “Although we hoped we would never see these invasive species in Montana waters, we’ve been preparing for this possibility for some time, and we’re going to work together to address this threat.”

Recent site inspections at Tiber and Canyon Ferry did not turn up any established populations of adult mussels, but officials will be conducting more extensive inspections with the assistance of stakeholders such as dam operators, marina concessionaires and other groups. 

FWP for many years has conducted regular testing of the state’s rivers, lakes and reservoirs for aquatic invasive mussels. Water samples from Fresno, Holter, and Hauser reservoirs have come back negative, as did samples from Lake Frances, the Marias River, and the Milk River. Testing at Fort Peck Reservoir and the entire Missouri River system is ongoing.

“The recent test results are definitely bad news, but they do indicate our detection system is working,” said Ryce. “The results from Tiber Reservoir show the larvae exist at very low densities, which improves our chances for containment.”

State agencies are making arrangements to bring in dogs that may detect mussels at Tiber and Canyon Ferry reservoirs. The dogs have proven effective in Canada and other states in identifying adult mussels attached to boats and other watercraft. At the reservoirs, the dogs will inspect boat docks, launches and shorelines.

Bryce Christiaens, chair of the governor-appointed MISAC, said “I’m pleased with the initial response from the agencies, and the expertise they bring to the issue.” He stressed the importance of all boaters and anglers practicing Montana’s “Clean – Drain – Dry” protocol:

  • Clean you boat and equipment every time you use it, especially if you move it to a new location.
  • Drain all standing water, including any that may be left in the engine’s cooling system, live wells, and bilge areas.
  • Dry everything that has come into contact with water.

Quagga and zebra mussels are aquatic invasive species not known to be established in Montana. In other parts of the country, such as the Midwest, Southwest and the Great Lakes areas, mussel populations have impaired hydroelectric, municipal and agricultural water infrastructure. The mussels can also impact fisheries and other aquatic resources; they can also damage recreation facilities.

For more information on aquatic invasive species, visit the Montana Invasive Species Advisory Council web page at, or FWP’s website