Thursday, May 21, 2009

Memorial Day boaters urged to keep zebra mussels in mind

By Jim Low
Conservation Department

OSAGE BEACH–A little caution by boaters over the Memorial Day weekend could save a lot of trouble and expense for Missourians in the long run.

That is the message from the Missouri Department of Conservation concerning the zebra mussel. The thumbnail-sized invader from Eurasia has galloped across much of North America in two decades and now has footholds in several Missouri waters. The only hope of slowing its spread lies in caution by boaters.

Zebra mussels cause several kinds of trouble. For one thing, they alter the ecology of waters they infest by competing with native fish and other animals for food. Their habit of attaching themselves to any solid object dooms native mussels, which are smothered by dense encrustations of the prolific invaders.

Zebra mussels have a hefty price tag for property owners, too. They weigh down docks, buoys and other objects exposed to water. Large numbers of mussels attached to boat hulls increase water drag, leading to higher fuel costs. Their tiny larvae, called “veligers,” get inside marine engines, live wells and water lines, requiring maintenance and creating a danger of damage due to overheating.

Zebra mussels also drive up utility bills by clogging water intakes of public and private utilities. Keeping those pipes open requires millions of dollars of maintenance annually.

And zebra mussels are only one of a growing number of invasive aquatic plants and animals that can hitch rides to previously uninfested waters on boats and other marine equipment.

An alert marina worker averted a zebra mussel infestation at Lake of the Ozarks in 2000 when he spotted thousands of tiny zebra mussels on the hull of a cabin cruiser brought to Missouri from out of state. Not everyone was so vigilant, however, for in 2006 marina workers, boaters and Conservation Department workers discovered zebra mussels at several locations in Lake of the Ozarks.

Today, Lake of the Ozarks has dozens of known infestation sites. The pests also have turned up in Lake Taneycomo, Bull Shoals Lake and in the Osage River below Bagnell Dam.

Most recently, zebra mussels have been discovered in the Missouri River in the Kansas City and Chamois areas.

No one has discovered an affordable way to eradicate the mussels once they are established in a lake or stream. Consequently, state officials can only hope to contain their spread to where they already exist and monitor other waters for new infestations.

Boaters are in a position to do more, however. Measures every Missouri angler and boater can take prevent the further spread of zebra mussel include:

· Thoroughly inspecting hulls, drive units, trim plates, transducers and other submerged portions of boats for adult zebra mussels after each use. Adults are fingernail sized with dark and light stripes. Small zebra mussels give hard surfaces a sandpapery feel.

· Examining crevices and recessed areas around motor housings, trim tabs and behind water intake screens on motors’ lower units.

· Checking trailers, ropes, minnow buckets and anything else that was in the water. Report any suspected zebra mussels to the nearest Conservation Department office.

· Removing all suspected zebra mussels, along with vegetation or other material clinging to boats and trailers and put it in a trash container.

· Rinsing boat bilges, trailers, motor drive units and live wells before launching them in another location helps prevent transferring microscopic zebra mussel larvae. Use water at least 104 degrees if live zebra mussels are found, or if your craft has been in waters known to be infested with zebra mussels. Most commercial car washes meet this standard.

· After rinsing, allow boats and other equipment to dry in the sun for at least five days before re-launching in a different lake or stream.

Some measures that help prevent the spread of zebra mussels also aid in stopping other aquatic pests, including the rusty crayfish and Asian carp. One of the best things anglers can do is dispose of live bait properly. Put unused bait in trash bags and deposit it in trash receptacles away from water. Never release unused bait – whether fish, worms, crayfish or anything else – into lakes or streams.

Boaters can prevent invasive plants and animals from hitching a ride by draining all water from bilges and live wells and removing vegetation and other trash from boats and trailers when they move them from one body of water to another.

More information about invasive aquatic species prevention is available at visit

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