University of Wisconsin Sea Grant Institute, 1992.  "Zebra Mussel Boater's Guide", University of Wisconsin Sea Grant Institute

A fact sheet produced by University of Wisconsin Sea Grant Institute and the Wisconsin Department of Natural Resources

"Zebra Mussel Boater’s Guide"

Zebra mussel alert

The barnacle-like zebra mussel poses a multi-billion dollar threat to North America’s industrial, agricultural and municipal water supplies, and it could become a costly nuisance for freshwater shipping, boating, fishing and clamming as well.

Zebra mussels look like small clams with a yellowish or brownish ‘D’ -shaped shell, usually with dark- and light-colored stripes (hence the name "zebra").

They can be up to two inches long, but most are under an inch. Zebra mussels usually grow in clusters containing numerous individuals and are generally found in shallow (6-30 feet), algae-rich water.

Zebra mussels are the ONLY freshwater mollusks that can firmly attach themselves to solid objects -- submerged rocks, dock pilings, boat hulls, water intake pipes, etc.

Zebra mussels are a potential threat to most water bodies in Wisconsin. Lakes or streams that receive a high amount of boat traffic are particularly at risk. The Great Lakes and Mississippi River are already infested with zebra mussels. By taking a few simple precautions, you can help stop the spread of zebra mussels to new inland waters.

If conditions are right, zebra mussels can attach in large numbers to any hard surface on your boat. Boats left at docks or marinas for long periods of time without being operated are particularly at risk. If present on a boat hull in large numbers, the mussels will cause increased friction and will decrease fuel efficiency. Removal of attached zebra mussels can remove paint and damage the surface layers of a boat.

The biggest threat for boat owners is the potential blockage of internal engine-cooling water passages. Larval zebra mussels can be drawn into engine passages where they may attach and develop into adult mussels.

Protect your boat

Run your boat at a high speed for 15-30 minutes once or twice a week. This will prevent newly settled mussels from attaching, may remove some settled mussels from the hull, and the engine temperatures generated should kill any mussels inside the water cooling system of the motor.

See your local boat dealer for nonfouling coatings that can be applied to your boat to protect it from zebra mussels.

Inspect cooling-water inlets and small spaces around the propeller before each use and remove any zebra mussels. Dispose of small quantities of zebra mussels as you would fish wastes - in the garbage. Watch for a reduction in cooling water discharge at each start-up. Monitor temperature gauges carefully. Any increase in operating temperature from the last time the boat was used is reason to suspect blockage.

Routinely remove screens and inspect intakes. At lay-up time, remove intake screens and examine internal passages. For inboard engines, disassemble between the seacock and engine, inspect and clean.

Protect inland waters

Boaters can unknowingly spread zebra mussels from infested to uninfested waters. Invisible in their early life-stages, zebra mussels are easily transported in water, in baitfish buckets and live wells. As adults they can attach to boat hulls, engines, trailers, fishing gear, or a number of other hard surfaces. The risk of infestation can be greatly reduced by following a few simple guidelines.

Upon removing the boat from the water, inspect the bottom, especially the underwater fittings; trim tabs and lower units. Rub your hand over the hull. If it feels grainy, there could be young zebra mussels attached. Remove any visible mussels. Put any zebra mussels you remove in the garbage, not back in the water.

Zebra mussels can attach to aquatic vegetation. It is very important to remove any plant material from your boat before leaving the boat landing.

Thoroughly drain the boat, the propulsion system, bilges, baitwell, coolers, anchor locker, and other places where water may lie.

Leave your boat out of the water in a sunny location to dry for several days.

Boat transferring guidelines

Drain all water from your boat and trailer including bilges, live wells, bait buckets, and engine compartments.
Inspect all surfaces of your boat that come in contact with the water, including your boat trailer.
Remove any zebra mussels or plant material you find. Put any zebra mussels you remove in the garbage not back in the water.
Dry boat and equipment In a sunny location for several days before transferring your boat to a new water system.
If you must transfer your boat to a new body of water in the same day, thoroughly wash boat and trailer with hot water. A car wash or similar facility is a convenient way to accomplish this task.

Contact: Local Sea Grant Communications Office
Keywords: Zebra_mussel, Inland_lakes/rivers, Prevention
Product Type: Outreach, Extension_Pub
User Type: Boating_and_shipping