Eurasian Ruffe

  • Eurasian Ruffe

     

    (Gymnocephalus cernuus)

    Eurasian Ruffe is a sharply spined fish native to northern Europe and Asia. A member of the perch family, it was likely introduced to North America through the dumping of ballast water by ships from Europe. It was first observed in western Lake Superior in 1986 and has since spread.

    Eurasian Ruffes mature quickly in 2 to 3 years, have rapid reproductive and growth rates and adapt quickly to new environments. They have a lifespan of about 7 years. They prefer turbid lakes with soft bottoms and little or no vegetation and rivers with slow moving current.

    Eurasian Ruffes are usually smaller than 20 cm long, but they have sharp spines on their gill covers and fins which discourage predators.

    Range

    Eurasian Ruffe have been recorded in the Kaministiquia River near Thunder Bay as well as more recently in the St. Lawrence River east of Kingston. It is also found in the United States in numerous rivers and bays along the southern shore of Lake Superior and in Lake Huron and Lake Michigan.

  • Identification

    • Eurasian Ruffe can resemble native members of the perch family and some other unrelated species. They differ from native Walleye (Sander vitreus), Yellow Perch (Perca flavescens) and Trout-Perch (Percopsis omiscomaycus) in a number of respects that aid identification:
    • They are usually less than 20 cm in length.
    • They do not have scales on their heads.
    • They have a down-turned mouth.
    • They are olive brown on their backs and pale on their sides.
    • They have two, joined dorsal fins; the front dorsal fin has 11 to 16 sharp spines with dark spots between each spine while the back one has soft rays (Trout Perch have no spines).
    • They also have sharp spines on their anal fins and gill covers.

    Impacts

    • Eurasian Ruffe compete for food and habitat with native species and prey on the eggs and young of native fish.
    • They can quickly become the dominant fish in local areas due to rapid reproductive and growth rates. Females can lay between 45,000 and 90,000 eggs per year in the St. Louis River area near Duluth, Minnesota, where Yellow Perch, Emerald Shiners and other forage fish numbers have declined significantly as Eurasian Ruffe numbers have increased.
    • Because they consume a variety of foods and have few predators, Eurasian Ruffes have the potential to spread to all of the Great Lakes and many inland water bodies.

    How can you help?

    • Learn to identify the Eurasian Ruffe and how to prevent its spread.
    • Always inspect your boat and equipment and clean it, removing any plants, animals or mud before leaving a water body.
    • Rinse all recreational equipment with high pressure and hot water or let dry in sunlight for 5 days.
    • Do not put any live fish into Ontario’s water bodies. Empty your bait bucket on dry land or freeze or salt bait for later use.
    • If you catch or observe an Eurasian Ruffe or other invasive species, please contact the Turtle Island Invaders hotline at 1-844-872-2348 (1-844-TRACE-IT) toll-free and report the sighting to your local Lands or Natural Resources officer.
    Chiefs of Ontario Eurasian Ruffe PDF
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