Location and Impact of the European Ruffe



     http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=7

http://en.wikipedia.org/wiki/Ruffe

     The Eurasian Ruffe is a freshwater fish native to the temperate regions in Europe and Northern Asia.  It has been introduced into the Great Lakes region of the United States with many unfortunate results.  The ruffe was first collected in 1986 from the St. Louis River at the border of Minnesota and Wisconsin. It subsequently spread into Duluth Harbor in Lake Superior and several tributaries of the lake.  It is found in the Amnicon, Flag, Iron, Middle, Raspberry, and Bad Rivers, Chequamegon Bay, and Apostle Islands National Lakeshore in Wisconsin.   It was found in Saxon Harbor, Wisconsin, and in the upper peninsula of Michigan at the mouths of the Black and Ontonagon rivers.  In the lower Peninsula of Michigan along Lake Huron, the first three specimens were caught at the mouth of the Thunder Bay River in August 1995.  This species has also been collected in Michigan in Lake Michigan, Lake Superior, Torch Lake, Little Bay de Noc in Escanaba, Big Bay de Noc, Misery River, Ontonagon River, Thunder Bay, and Sturgeon River Sloughs.  The ruffe has been collected in Lake Superior at Thunder Bay Harbour, Ontario, Canada.  The ruffe was probably introduced via ship ballast water discharged from a vessel arriving from a Eurasian port, possibly as early as 1982-1983.  Recent genetic research has indicated that the origin of ruffe introduced to the Great Lakes was southern Europe, not the Baltic Sea as previously believed. 

Impact:
      -The ruffe has affected fish populations in other areas where introduced. In Scotland, native perch populations declined, and in Russia whitefish numbers have declined because of egg predation by ruffe.

      -Ruffe exhibit rapid growth and high reproductive output, and adapt to a wide range of habitat types therefore the species may pose a threat to native North American fish.
      -Yellow perch, emerald shiners, and trout-perch have all declined since the introduction of the ruffe.
      -There is much concern that ruffe may have a detrimental effect on more desirable species in Lake Superior, such as yellow perch and walleye, by feeding on the young of these species or by competing.
      -Findings indicated that the species prey heavily on benthic insects thereby suggesting that ruffe compete for food with yellow perch, trout-perch, and other native benthic-feeding fishes.
      -Ruffe hold an advantage over native perch in their ability to better select moving objects under relatively dim light conditions or at high turbidity.
      -Ruffe have a very sensitive lateral line system and night adapted vision, and are more adapted to foraging under poor light conditions that yellow perch.
      -In a study of ruffe predation by native pike, bass, bullhead, walleye, and perch found that though ruffe comprised 71-88% of prey species biomass, all five of the selected predators ate ruffe at lower proportions, preferentially selecting native fish species.