Credit Frank Stone, USFWS

The Ashland Fishery Resources Office (FRO) completed fall sampling of the invasive fish, ruffe, in three Wisconsin tributaries and one Michigan tributary to Lake Superior.  Sampling is also conducted during spring and summer and the results are averaged to account for seasonal variation.  This ongoing investigation was initiated in 1995 to compare trends in abundance of ruffe and native fish populations, one of eight elements in the Ruffe Control Program. 

A total of 6,571 fish representing 21 species were captured in bottom trawls including one invasive species, ruffe.  All fish were released except ruffe.  Brown Bullhead and trout-perch comprised 83% of the total catch.  Ruffe comprised less than 8% of the total catch, and ruffe young-of-the-year comprised 75% of the total ruffe catch.

Yellow perch, a species demonstrated by experimental research to be impacted by ruffe, comprised just over 6% of the total catch.  A strong presence of brown bullhead in the Flag River, indicated by a total catch of over 3,150, may help to control ruffe abundance in that tributary.