A ruffe captured in Green Bay, near Marinette, Wisconsin. - FWS photo by Dale Hanson

Biologists Ted Eggebraaten and Dale Hanson conduct a trawl for ruffe along the power plant dock. - FWS photo by Dale Hanson

In June, a suspected eurasian ruffe was captured by a commercial fisherman in Green Bay near Marinette, Wisconsin.  The fish was sent to the Green Bay Fishery Resources Office (GBFRO) where the ruffe identification was confirmed.   

Invasive ruffe arrived in the Great Lakes through infected ballast water and were first identified from western Lake Superior in 1986.  They had spread to northern Green Bay (Little Bay de Noc) by 2002 and this latest confirmation shows the invasive ruffe are expanding their range in Lake Michigan. 

Biologists Dale Hanson and Ted Eggebraaten conducted a follow-up survey in August to evaluate whether ruffe were present in the southern portion of Green Bay near the industrial commercial port at the mouth of the Fox River. 

Bottom trawling was used to sample the fish community.  No ruffe were encountered in the trawl catches but non-natives  including round gobies and white perch were captured.  At this time it appears ruffe have not spread to southern Green Bay, at least not in detectable numbers. 

As ruffe continue to expand they will become yet another established exotic species that will disrupt the native community balance.  The most serious impacts of ruffe may be on yellow perch populations where competitive interactions between the species may have adverse affects on perch recruitment and growth.