Ruffe.

The Wisconsin Department of Natural Resources reported that commercial fisherman, Jim Benson, captured a ruffe near Peshtigo Harbor, Wisconsin, in Green Bay of Lake Michigan on May 28^th, 2008.  The capture was made at a depth of 12 meters, and it confirms a range expansion of 15 kilometers south from a previous capture site near Marinette Harbor, Wisconsin, in 2007.  The ruffe capture near Marinette was also made by Jim Benson.  Commercial fishing operators as well as sport anglers continue to be a valuable source of aquatic invasive species early detection.

Native to Europe and Asia, ruffe likely hitchhiked aboard ocean shipping, first appearing in western Lake Superior near Duluth, Minnesota, in 1986.  In 1995, ruffe first appeared in the Thunder Bay River, a tributary of Lake Huron near Alpena, Michigan, a likely hitchhike aboard intra-Great Lakes shipping.  In 2002, ruffe were first detected in Little Bay de Noc of Lake Michigan, near Escanaba, Michigan, a commercial port in northern Green Bay.  In Little Bay de Noc, the pathway of ruffe introduction remains uncertain, since an investigation of shipping history revealed that no ships discharging ballast water in Escanaba Harbor took on ballast water in ruffe infested waters.  In addition, all intra-Great Lakes shipping taking on ballast water in ruffe infested waters of western Lake Superior exchange that ballast water in the deep waters (40 fathoms or greater) of Lake Superior, where ruffe are not likely to survive.  Compliance with ballast water exchange in Lake Superior is voluntary, but periodic examination of ship's logs has revealed 100% compliance since the exchange plan was enacted in 1997.   

Impossible to eliminate from the open waters of the Great Lakes, efforts concentrated on delaying ruffe range expansion by controlling the pathways of introduction, with the exception of natural migration, and by population reduction where feasible.  The result has been and continues to be a successful delay in ruffe range expansion.  Limiting the spread of ruffe to natural migration, combined with exposure of ruffe to areas of unpreferred habitat resulted in a time span of 20 years (1986-2006) before the ruffe reached eastern Lake Superior.  Likewise, ruffe have never been detected outside of the Thunder Bay River and Thunder Bay in Lake Huron, and no ruffe have been captured there or anywhere in Lake Huron since 2003.  In the Thunder Bay River, population reduction was feasible, and likely contributed to stop the further spread of ruffe there. In Lake Michigan, ruffe remained confined to northern Green Bay for five years (2002-2007) before likely migrating south naturally.  In the Lower Great Lakes, ruffe remain undetected, as well as in all inland lakes and streams in the Great Lakes Basin.