Zebra mussel awareness critical on Labor Day weekend

Holiday travel increases the chances of spreading this exotic invader.

CAMDENTON, Mo.-With Labor Day approaching, officials with the Missouri Department of Conservation remind anglers and recreational boaters to protect the state's waters from zebra mussels.

The zebra mussel (Dreissena polymorpha) is native to the Caspian Sea. It entered North America in the ballast tanks of ocean-going ships about 20 years ago. After gaining a foothold in the Great Lakes, it began spreading through the Mississippi River and its tributaries. The pest recently was found on boat docks at Lake of the Ozarks. That was the first documented infestation in Missouri's interior waters, although they infested the Mississippi River adjacent to Missouri about 15 years ago.

Adult zebra mussels attach to solid objects and gather food by filtering tiny plants and animals from the surrounding water. Each female can produce up to a million offspring a year. They can form dense colonies several layers thick, encrusting objects with their shells.

Heavy zebra mussel infestations can clog water intakes of boat motors and power plants, compete with native animals for food and smother native mussels, many of which already are endangered. Zebra mussels also compete with native animals for food, upsetting the ecological balance of healthy lakes and streams.

"Knowing what zebra mussels can do and how easily they can be spread, I think everyone who fishes or owns a boat or personal watercraft in Missouri needs to be watchful," said Steve McMurray, the Missouri Department of Conservation's expert on mussels. "The threat from zebra mussels is something that Missourians need to make part of their day-to-day awareness, and holiday travel presents a special risk."

McMurray said boaters at Lake of the Ozarks should take precautions against zebra mussel spread when moving their craft to other waters. He said the same is true for those bringing boats to Missouri from other states.

Before moving a boat between waters, slide your hand along the hull and other submerged surfaces. A rough or grainy texture could indicate the presence of hundreds of tiny zebra mussels.

Remove any vegetation or other material that is caught on the boat or trailer, and scrape off any suspected zebra mussels before moving to another location.

Adult zebra mussels are dime- to quarter-sized. Their shells have black and white zigzag markings. You can get a pocket identification card and brochure by contacting MDC, Zebra Mussel Watch Card and Zebra Mussel: Missouri's Most Unwanted, P.O. Box 180, Jefferson City, MO 65102. Or e-mail a request for these publications to pubstaff@mdc.mo.gov.

There are other important measures to take to prevent spreading zebra mussels. Drain water from the motor, live well, bilge and transom wells and any other water from your boat and equipment while on land before leaving any water body. Dump leftover bait in a secure trash container away from water before leaving any water body. Do not take leftover live bait from one body of water to another.

Before launching your boat again, thoroughly rinse and dry the hull, drive unit, live wells, live well pumping system, bilge, trailer, bait buckets, engine cooling system and other boat parts with a hard spray from a garden hose.

If your boat was in infested waters for a long period of time, or if you find any attached adult mussels, use hot (104 F) water instead of cold, or take the boat to a do-it-yourself carwash and use the high pressure hot water to "de-mussel" boat and trailer. Do not use chlorine bleach or other environmentally unsound washing solutions unless you can capture and properly dispose of the rinse water.

Let boats, motors and trailers dry thoroughly in the sun for at least five days before boating again. In infested waters, the best way to keep a hull mussel-free is to run the boat frequently. Small juvenile mussels are quite soft and are scoured off the hull at high speeds.

Leave outboards or outdrives in the up position when not in use. Periodically inspect hulls and drive units, and scrape off mussels. Pump hot water through your engine's intake on a regular basis to prevent mussel growth inside the engine's cooling system.

Consult the Conservation Department before trying to control zebra mussels or any other exotic pest. Pest species often thrive on disturbance. Do-it-yourself control treatments can make matters worse and can harm native species.

Several Missouri Stream Teams are monitoring lakes and streams for zebra mussels. If you would like to join the effort, call (800) 781-989 or visit the Stream Team web-site at www.mostreamteam.org.

For more information about zebra mussels, visit www.protectyourwaters.net. To report a potential zebra mussel sighting, contact the nearest Missouri Conservation Department office or go to: www.mdc.mo.gov/nathis/exotic/zebra/: www.missouriconservation.org/nathis/exotic/zebra/.

-Jim Low-