Zebra Mussel

The zebra mussel is yet to be found in Montana, but it’s getting closer (map). Zebra mussels look like small clams with a D-shaped shell. They usually have dark and light-colored stripes. When they are very young, they look like pepper and feel like sandpaper on a smooth surface. Mature zebra mussels are generally the size of a fingernail.The zebra mussel is one of the most economically damaging aquatic organisms to invade the United States. Its destructive power lies in its sheer numbers and its ability to attach itself to solid objects water intake pipes, propellers, boat hulls, dock pilings, submerged rocks and even other aquatic animals. Colonies of zebra mussels clog filters, pipes, and pumps, and threaten native invertebrates, fish and wildlife. Zebra mussels consume food other species need and can completely change the ecology of infested waters. They can also ruin boat engines by growing in the cooling system intakes and blocking water flow, and can jam steering equipment.

• United States Geological Survey’s page on zebra mussels. http://nas.er.usgs.gov/taxgroup/mollusks/zebramussel/.
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• Wikipedia. Excellent information, especially on the history of the critter’ spread. http://en.wikipedia.org/wiki/Zebra_mussel.
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• National Atlas. Maps. http://nationalatlas.gov/articles/biology/a_zm.html.
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• Montana Department of Fish, Wildlife, and Parks’ page on zebra mussels. http://fwp.mt.gov/fishing/fishingmontana/ans/Molluscs.html.
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• A State Under Siege. MDFWP magazine article. http://fwp.mt.gov/mtoutdoors/HTML/articles/2003/ANS.htm#least.

Quagga mussel — it thrives in cold water

You don’t want to meet dreissena rostriformis bugensis. First found in the Great Lakes a quarter century ago, and slightly larger than its inch-long relative (identification information from the USGS), the zebra mussel (top left), the quagga (bottom left), indigenous to the Ukraine’s Dneiper River basin, which drains into the Black Sea, is a filter feeding bivalve that clogs pipes, fouls pumps, covers pilings and rocks, displaces native mollusks, reproduces rapidly, and causes enormous economic damage while profoundly perturbing native ecosystems. Unlike the zebra mussel, the quagga mussel likes cold water.

the quagga hitched rides on the boats of Sunday sailors and now inhabits the American West. Flathead Lake is still quagga-free — but the mussel is now firmly established in Lake Mead, where millions were discovered earlier this year. Lake Mead is next to Highway 93, so these destructive little creatures now have a direct route to Flathead Lake. The quagga also may be established in Lake Powell, according to a report in the August 10 issue of the Salt Lake Tribune.

More information:

• Quagga mussel fact sheet, prepared by the USGS.
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• Quagga v. zebra FAQ, also from the USGS.

Actions You Can Take

• Before leaving any waterbody:
• Remove all plants, sediment or animals from your boat and trailer.
• Drain all water from your boat, including from the motor, live well and bilge. Do not transfer any water from one waterbody into another.
• Never release live bait into a waterbody or transport aquatic animals from one waterbody into another. Always discard unwanted bait with household trash in the landfill. Likewise, dispose of fish carcasses with trash.
• Wash your boat, trailer and all fishing gear and equipment. High pressure hot water is best.
• Air dry your boat and equipment for as long as possible between fishing trips.

• If you find a zebra or quagga mussel:
• Note the date and location where the sample was found.
• Store the mussel or a piece of the plant in rubbing (isopropyl) alcohol.
• Contact your local Montana Fish, Wildlife and Parks office or call the Aquatic Nuisance Species Coordinator at 406-444-2448 as soon as possible. The earlier we detect a new infestation the better.