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Exotic species, those not native to the region, have caused "biological pollution" to the Lake Michigan and the other Great Lakes since the 1800s. Subsequent to European settlement, well over 100 exotic aquatic organisms have become established in the Great Lakes.
As human activity has increased, the rate of introduction has increased. More than 1/3 of these exotic species have been introduced in the past 30 years, a major increase coinciding with the opening of the St. Lawrence Seaway.
Many exotic species pose an economic or ecological threat to Lake Michigan and other waters of Indiana and neighboring states. Harmful exotic species associated with our waters are sometimes called aquatic nuisance species. Examples of aquatic nuisance species include several fish (gobies, ruffes, sea lampreys, alewives, white perch, and common carp); mollusks and crustaceans (zebra mussels, rusty crayfish, and spiny water fleas); and plants (Eurasian watermilfoil, curly-leaf pondweed, and purple loosestrife).
Zebra mussels have proven particularly costly. Already well-established in Lake Michigan, zebra mussels colonize and clog water intakes; millions of dollars are expended annually in an effort to keep intakes open. Zebra mussels may replace native species of mollusks. They are also suspected of contributing to the great decline in yellow perch populations experienced in recent years.
Boaters can play an important role in the control of the spread of zebra mussels and other aquatic nuisance species. Zebra mussels may be unintentionally transported from one lake or stream to another by the movement of boats containing a life-form of the zebra mussel. Adult zebra mussels can be transported to new areas by hitchhiking on watercrafts. they can attach to boats and trailers, and survive for a week or more out of the water. The larvae will drift with the currents and can be transported in the water. In fact, the mussels can be found in a bilge, bait bucket, ballast water, live will and engine cooling units.
In December 1996, the Indiana Natural Resources Commission adopted a Zebra Mussel Containment Policy. The policy promotes precautionary steps to be taken by boaters to reduce the likelihood zebra mussels will infest inland lakes and streams in Indiana and in neighboring states.
Recreational boaters can slow or stop the spread of zebra mussels by taking a few simple precautions.
Inspect your boat, trailer or engine or any area that comes in contact with water which is infested with zebra mussels.
Dispose of mussels properly in the trash. Do not leave them at the water's edge because that may hasten the spread of the mussel.
Do not transport bait fish or water from any areas to other waters. You may be transporting the invisible larval stages.
Leave your boat out of the water for at least 10 days. Mussels cannot usually live long without water.
Because larval mussels can survive for about a month in areas that contain trapped water, it is important to flush the motor and other water-retaining areas of your boat with a chlorine solution. You should also clean your boat, motor, trailer, bait bucket and live well with a salt solution (1/2 cup of salt per gallon of water, 100F) or a bleach solution (one part bleach/10 parts water) if the boat has been operated in infested waters. High pressure washing can also dislodge mussels from hidden areas.
Keep an eye on your boat's temperature gauge. Zebra mussels can damage your boat equipment by fouling the cooling system. A hot-running engine may indicate your cooling system is infested.
For more information contact the Indiana Department of Natural Resources, Division of Fish and Wildlife, 100 W. Water Street, Michigan City, Indiana, 46360.