The Eurasian ruffe is a perch-like invasive fish species that was first found in the Great Lakes in western Lake Superior during the 1980's. They are believed to have been accidentally transported to the Great Lakes in the ballast water of an ocean-going ship. 

In 1995 ruffe were discovered in Lake Huron in the Thunder Bay River. The abundance of ruffe in the Thunder Bay River slowly increased and peaked in 1999, when they were the most abundant bottom dwelling fish captured during fall trawling surveys.  Efforts were initiated to remove spawning adult ruffe in the spring to prevent reproduction and to remove young-of-the-year ruffe captured in the fall.  Their abundance declined and they were last captured in the spring of 2003.

It is believed that Eurasian ruffe may have become extirpated from the Thunder Bay area and Lake Huron based on survey findings from 2003 to present. We are unsure why ruffe have disappeared from the area but believe it may be related to the subsequent invasion of the round goby, another aggressive bottom dwelling invasive, and/or our removal efforts.  The possible extirpation of ruffe is a remarkable outcome considering established invasive species generally become a part of the fish community into the future. Ruffe continue to persist in Lake Superior and in the Green Bay area of Lake Michigan.