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Aquatic Nuisance Species

Over the next several years, thousands of recreationists and recreational boaters are expected to commemorate the 200th Anniversary of the Lewis and Clark Expedition, most of which was on major waterways. One unintended, but potentially harmful, side effect of the Bicentennial could be the introduction of aquatic nuisance species, both plants and animals, into the lakes and rivers of the Western United States.

Many species travel to new waterways on boats and trailers. Some species can live outside of water for 10 days. Once introduced, aquatic nuisance species may cost taxpayers and businesses millions of dollars to control.

The Zebra Mussel can clog power plant, irrigation, and public water supply intakes and pipes. The mussels can damage boat engines and blanket shorelines with their foul smelling sharp shells. They consume food meant for native species and smother native mussels.

Whirling Disease caused a 90% decline in the rainbow trout population of the Madison River from 1990 to 1995.

Since their detection in 1994, New Zealand Mudsnails spread to occupy the entire mainstem Madison River. They are unique because their populations are primarily composed of females that reproduce by cloning themselves. It takes only one immature New Zealand Mudsnail to start a new population which may impact native species and fisheries.

The best line of defense against introductions and spread of aquatic nuisance species is PREVENTION. Please help maintain a healthy environment for Montana's aquatic species and for your recreational activities. Before leaving a water site: thoroughly inspect and clean your boat and gear, drain wells and bilges, and dispose of harvested animal remains at the site or in the trash. In addition, make sure that you thoroughly dry your boat and equipment before using it in another body of water.

How You Can Help

Many aquatic nuisance species can live several days out of water and may be attached to or carried in boats, boat trailers, waders, or other gear that contacts the water.

As you leave a body of water:

  • Inspect your boat, trailer and gear.
  • Remove any plants, animals and mud.
  • Drain lake or river water from your motor, live well, and bilge while on land.
  • Dispose of harvested animal remains and unwanted live bait on land at the site taken or in a trash receptacle.
  • Rinse your boat, trailer, and gear with high-pressure or hot water.
  • Dry your boat and equipment for as long as possible (five days is optimal).

What To Look For

Whirling Disease organism is microscopic, and invisible to the naked eye. It travels in water, mud and vegetation, so follow prevention techniques carefully.

Zebra MusselZebra Mussels on a stick

The Zebra Mussel looks like a small clam with a D-shaped shell. Usually it has alternating dark and light stripes, is the size of a fingernail, is found attached to hard surfaces in clusters and young zebra mussels look like black pepper and feel like sandpaper when attached to a boat surface.

New Zealand MudsnailsNew Zealand Mudsnails

New Zealand Mudsnails are very small; the largest adults are about 5 mm in length (1/8 in.), while newly born New Zealand Mudsnails appear as a tiny grain of sand. They have brown or black cone-shaped shells with five whorls. These mudsnails spread easily by becoming wedged into wader seams, soles and felt of wading boots, Velcro, and by working their way past gravel guards into the inside of waders boots.

What to do if you see a boat that appears to be carrying zebra mussels or other aquatic nuisance species:

  • Talk to the boat owner and encourage him or her to clean their boat and other gear before placing it in any water body.
  • If possible, alert a nearby park warden or fish and game representative.
  • Call 1-800-437-2744 and report the sighting.
  • Call your local state fish and game representative and report the sighting, including a vehicle description and license number. Often times, an agency representative will come to the scene.

For more information on aquatic nuisance species, visit USFWS ANS Task Force.