Download Eurasian Ruffe (Gymnocephalus cernuus)

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:
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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:
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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.
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There are also sharp spines on their anal fins and gill covers.
They have no scales on the head.
What You Can Do
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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
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Invasive Species: A Threat to Ontario's Biodiversity
Invasive Species Centre
OFAH/OMNR Invading Species Awareness Program. (2012). Eurasian Ruffe. Retrieved
from: http://www.invadingspecies.com. This factsheet may be reproduced for non-commercial
purposes.