agricultural inspection stations have reported finding mussels on the hulls or motor compartments of at least 19 trailered boats arriving into the state. In addition to being able to travel long distances during both immature and mature stages of life, zebra mussels can produce up to several hundred thousand eggs in a single season. Zebra mussels are most disruptive in two ways. The first is that they can colonize and clog water supply pipes, thereby restricting water flow for systems used for cooling, fire-fighting, hydroelectricity, etc. Colonies can also be very dense: it was reported that at one power plant in Michigan, 700,000/m2 of zebra mussels were found in the pipes, the diameters of which were reduced by two-thirds. The United States Fish and Wildlife Service once estimated that zebra mussel infestations could cost $500 million per year due to increased costs for utility companies and industrial plants, as well as loss of income revenue for fishing and fishing-related businesses. The economic repercussions of this type of species invasion can be devastating. The second issue with zebra mussel invasions is that they can deplete food sources in aquatic ecosystems. Zebra mussels are filter feeders, meaning that they consume microorganisms, and they do so at very fast rates. Microorganisms form the bottom of the food chain, and eliminating that food source can be dangerous to the survival of native species. The spread of the nonindigenous zebra mussels have greatly decreased the numbers of native mussels in Lake St. Clair and Lake Erie, which may be at risk for extinction. Eurasian ruffe The Eurasian Ruffe (Gymnocephalus cernuss) is another aquatic nuisance species that has spread to the Great Lakes, Wisconsin, and Michigan, after first being discovered in the St. Louis River Estuary of the Duluth-Superior Harbor in 1986. Originally from southern Europe, the ruffe is believed to have arrived in North America through the release of ballast water from foreign seas. The Eurasian ruffe is an extremely aggressive species. It can produce 200,000 eggs in the first batch and 6,000 eggs in later batches, and it is able to thrive in a number of different habitats where waters range from fresh to brackish, in ranges of depth from 0.25m to 85m. A fierce competitor for food sources, it feeds on plankton, bottom-dwelling insect larvae, and sometimes fish eggs. One advantage that the ruffe has over native species is better eyesight in dark