Aquatic Invasive Species Issues

Eurasian Ruffe

Eurasian ruffe Gymnocephalus cernuus Photo USFWS.

The Eurasian ruffe, Gymnocephalus cernuus, (ruffe) is a freshwater fish native to Eurasia. It is thought to have been transported and accidentally released into the Great Lakes from the ballast water of ships traveling from Europe. The ruffe was first reported in in western Lake Superior in 1986 at the St. Louis River harbor in Duluth, Minnesota and Superior, Wisconsin. They have since spread within the upper Great Lakes.

Ruffe can spawn multiple times in a year allowing it to become abundant quickly. They are also able to feed in complete darkness. These characteristics may allow ruffe to compete with native fish species for food and habitat resources. Efforts are underway in Lake Huron to monitor its current status, control current populations, measure the effects of this invader on existing fish communities, and to educate anglers in an effort to prevent its spread.

Learning to identify the Eurasian ruffe and knowing where they are found are important steps toward preventing or deterring their spread to new areas.

Identifying Characteristics

The ruffe is a member of the perch family and resembles perch in body shape. Identifying characteristics are shown on the image below.

 

Distribution

Eurasian ruffe distribution in the Great Lakes Basin. Image provided by USGS.

Ruffe are present in Lake Superior, Lake Michigan, and Lake Huron. Within Lake Huron ruffe have only been found in the Thunder Bay River and nearshore areas around Alpena, Michigan. Recently the population of ruffe in Thunder Bay has declined and they have not been captured from the area since 2003. The cause for the decline and dissappearance of ruffe in Thunder Bay is unknown.

Resource Materials

Learn how you can prevent the spread of invasive species - Learn now

What you should do if you catch an invasive species - Learn now

 

 

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