Background

Eurasian Ruffe is a small member of the perch family (Percidae sp.) and is native to northern Europe and Asia. It is suspected to have been 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 as well as 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 suspected to be spreading east along the northern shores of Lake Superior and have been recently confirmed just outside of Sault Ste. Marie, Ontario. They are also found in the United States along the southern shore of Lake Superior, Lake Michigan, and Lake Huron.

For an up to date distribution map of Eurasian Ruffe in Ontario, visit www.EDDMapS.org/distribution.

Impacts of Eurasian Ruffe

Ruffe consume a variety of different food items and have few predators due to the presence of hard dorsal spines on their fins, making 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 negatively impact native sportfish populations, such as Yellow Perch, by directly competing for food, habitat, or through heavy predation of native sportfish eggs.
• Ruffe can 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 each of the Great Lakes and many inland waters, as well.

How to Identify Eurasian Ruffe

Ruffe resembles juvenile Walleye, Yellow Perch and Trout Perch, but they differ from these species in the following ways:

• Their perch-like body is less than 20 cm (8 in) long, with glassy eyes and a down-turned mouth.
• Their colouring is olive-brown on their back, with pale sides.
• They lack the dark vertical stripes found on the native Yellow Perch.
• Their front and back 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. Yellow Perch and Walleye, by contrast, have separated dorsal fins.
• 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.
• Don’t release any live fish into Ontario lakes or rivers. Empty your bait bucket on dry land, freeze, or salt your bait for later use.
• Return or donate unwanted aquarium fish to a pet store or local school.
• If you’ve seen Eurasian Ruffe or another invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711, visit EDDMapS, or search for the ‘Invasive Species in Ontario’ project on iNaturalist.org to report a sighting.

Resource Files

Other Resources

• Ontario Ministry of Natural Resources and Forestry
• Invasive Species Centre

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