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Ruffe
Eurasian Ruffe
Gymnocephalus cernuus

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Carassius auratus

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Channa argus

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Osmerus mordax

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Neogobius melanostomus

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Scardinus erythropthalmus

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Petromyzon marinus

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Proterorhinus semilunaris


( Fish illustrations by Joe Tomelleri )

Eurasian Ruffe
Gymnocephalus cernuus

Eurasian ruffe is a small member of the perch family and is native to northern Europe and Asia. It was likely transported to North America in the ballast water of vessels arriving from Europe in the mid 1980's. In order to prevent the spread of this invasive species to new areas, the Ontario government, and some American States, have banned the possession and sale of live or dead Eurasian ruffe, and using ruffe as bait.

Eurasian ruffe are capable of adapting to a wide range of environmental conditions including fresh or brackish water with low or high nutrients, and a wide range of depths and temperatures. They are also capable of spawning in a wide variety of conditions and habitats.

Range

In Ontario, Eurasian ruffe have been recorded in Kaministiquia River near Thunder Bay. They are also found in the United States along the southern shore of Lake Superior, Michigan, and Huron.

Impacts of Eurasian Ruffe

Ruffe consume a variety of different food and have very few predators because the hard spines on their fins make them difficult for other organisms to eat. They mature quickly (2-3 years) and have an average lifespan of 7 years. This species has the potential to affect ecosystems in the following ways:

  • They can seriously damage native sportfish populations, such as, yellow perch by directly competing for food, habitat or through heavy predation of native sportfish eggs.
  • Ruffe can very quickly become the most dominant fish in local areas because of their rapid reproductive and growth rates. This puts pressure on native species and contributes to their decline.
  • Given time, they have the potential to spread to all of the Great Lakes and many inland waters as well.

How to Identify Eurasian Ruffe

Ruffe resemble young walleye, yellow perch and trout perch, but they differ from these species in the following ways:

  • Their perch-like body is less than 20cm long, with glassy eyes and a down-turned mouth.
  • Their colouring is olive-brown on their back, with pale sides.
  • Their two dorsal fins are joined; the first fin has 11-16 stiff, sharp spines with rows of dark spots between them, and the second dorsal fin has soft, flexible rays.
  • There are also sharp spines on their anal fins and gill covers.
  • They have no scales on the head.

What You Can Do

  • Learn how to identify eurasian ruffe, and how to prevent accidentally spreading this invasive species.
  • Inspect your boat, trailer and equipment after each use. Remove all plants, animals and mud before moving to a new water body.
  • Don't release any live fish into Ontario lakes or rivers. Empty your bait bucket on dry land, or freeze or salt the bait for later use.
  • Return or donate unwanted aquarium fish to a pet store or local school.
  • Rinse all recreational equipment with high pressure (>250 psi), hot water (50°C / 122°F) OR let it dry in the sun for at least 5 days.
  • If you've seen an Eurasian Ruffe or other invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711, or report a sighting online.

Other Resources

Photo Gallery

Downloads

Icon of Ruffe Distribution Map Ruffe Distribution Map (1.7 MiB)
Icon of Workshop Manual: Aquatic Invasive Species Workshop Manual: Aquatic Invasive Species (2.5 MiB)
Icon of Field Guide to Aquatic Invasive Species 3rd Edition Field Guide to Aquatic Invasive Species 3rd Edition (3.5 MiB)