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Overview | General Resources | Related Resources
Current invaders:
Crustaceans: Rusty Crayfish | Spiny Water Flea
Fish: Goby (Round) | Goby (Tubenose) | Rudd | Ruffe | Sea Lamprey | White Perch
Mollusks: Quagga Mussel | Zebra Mussel
Plants: Curly-leaf Pondweed | Eurasian Watermilfoil | Phragmites (non-native) | Purple Loosestrife
Viruses: Viral Hemorrhagic Septicemia Virus (VHSv)
Potential invaders:
Fish: Asian Carp

[Invasive species home page]

What's New
Salties bring no new invaders, thanks to ‘swish and spit’
Duluth News Tribune (4/11)
Supporters say saltwater flush is working to thwart invasives until ballast treatment arrives in Great Lakes.

Cleaning up the Great Lakes
The Voice (7/30)
New standards governing the cleaning of ballast water in ocean-going freighters, about to be adopted by the U.S. Coast Guard, should help prevent release of non-native species into the Great Lakes and other threatened U.S. waters.

Luring an invasive fish with pheromones
Great Lakes Radio Consortium (1/3)
The discovery of a chemical compound that attracts an invasive fish could be a breakthrough in controlling harmful fish populations.

Threat increasing from invasive fish
Great Lakes Radio Consortium (9/9)
A spiny fish that can hunt in the dark has invaded Lake Michigan. The foreign fish is known as the Eurasian ruffe.

Another non-native fish species poses threat to lake ecosystem
Chicago Sun-Times (9/4)
The Eurasian ruffe, a small, spiny fish native to the Black and Caspian seas, has been found in the waters of Lake Michigan, which has wildlife biologists worried.

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The Ruffe The ruffe (Gymnocephalus cernuus), a small spiny perch capable of explosive population growth, is one of the latest foreign arrivals threatening the Great Lakes fishery. Native to lakes and rivers in Eurasia, the ruffe was introduced to Duluth Harbor on Lake Superior via ballast water of an ocean going vessel and first collected in fish surveys in 1986.
The ruffe competes with native fish for food and habitat. Its ability to displace other species in newly invaded areas is due to its high reproductive rate, its feeding efficiency across a wide range of environmental conditions, and characterstics that may discourage would-be predators such as walleye and pike.
Ruffe grow rapidly and can reproduce in their first year. In the St. Louis River, near Duluth, Minnesota, females can lay between 45,000 and 90,000 eggs a year. Ruffe are primarily bottom feeders, preferring dark environments where they can hide from predators. Ruffe rarely grow bigger than 5 inches, although the sharp spines on their gill covers, dorsal and anal fins make them difficult for larger fish to eat.
Likely means of spread: Ruffe could be accidentally transported in livewells, bilge water, bait buckets, and in the ballast water of Great Lakes freighters.

Photo Credit: Minnesota Sea Grant
References: A Field Guide to Aquatic Exotic Plants and Animals, University of Minnesota Sea Grant Program

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General Resources
Distribution map of Ruffe
U.S. Geological Survey (USGS)

Eurasian Ruffe Factsheet
U.S. Geological Survey (USGS), Great Lakes Science Center
Outlines potential impacts of Eurasian Ruffe in the Great Lakes and how it can be controlled.

Factsheet: Ruffe
Ohio Sea Grant College Program

Fishery Management Officials Re-Examine Ruffe Control Strategy After the Recent Appearance of Ruffe in Lake Huron
Council of Lake Committees, Great Lakes Fishery Commission
Officials agree that ruffe movement warrants a new approach to deal with this exotic menace. November 15, 1995.

Gymnocephalus cernuus
U.S. Geological Survey (USGS)
Nonindigenous occurrences, map, means of introduction, and impact of the Ruffe.

Ruffe (Gymnocephalus cernuus)
Sea Grant Nonindigenous Species Site (SGNIS)
Includes scientifically reviewed articles as well as images from Sea Grant researchers.

Ruffe Home Page
University of Minnesota
This page points to ruffe researchers, news articles and more.

Ruffe ID Card
Minnesota Sea Grant Program
Informative fact sheet on the ruffe, 1998.

Ruffe: A New Threat to our Fisheries
Minnesota Sea Grant Program
Informative fact sheet on the ruffe, 1997.

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Related Resources
GLIN: Agencies and Organizations, Fauna
GLIN: Fish and Fisheries in the Great Lakes Region

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Updated: December 15, 2017
Selected Photos: Copyright ©John and Ann Mahan
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