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Another non-native fish species poses threat

A small, spiny fish native to the Black and Caspian seas has made its way to Lake Michigan, and that has biologists worried. The Eurasian ruffe was discovered late last month off the waters of Escanaba, Mich., according to the U.S. Fish and Wildlife Service.

"The addition of any exotic species is not a good thing," said Gary Lambert, a professor in the department of biological sciences at the University of Notre Dame who has studied the ruffe extensively. "The problem with the ruffe is they are closely related to yellow perch. They have the same food preferences and live in the same habitats. If there's limited food for both, everyone is scrambling for the same food, and both suffer."

Ruffe average 4 to 6 inches long and are known for their spiny fins. The freshwater species has been in Lake Superior for years, probably having been brought over inadvertently in a ship's ballast, said Dave Radloff, a biologist for the U.S. Fish and Wildlife Service.

Ruffe's not the first choice of other fish looking for food, sports fishermen don't angle for ruffe, and the fish have no commercial value. But they mature quickly and reproduce easily, making it easy to quickly get a toehold in new waters.

Lambert and others have warned that it was only a matter of time before they moved south into Lake Michigan. Now, environmentalists must determine how the fish migrated and try to slow or stop their spread.

"If they move into southern Lake Michigan, it is possible they could enter the Mississippi River ecosystem through the Chicago Canal system," said Bill Hartwig, the U.S. Fish and Wildlife Service's regional director.

The ruffe found in Lake Michigan likely migrated from Lake Superior, where they were first discovered in the mid-1980s near Duluth, Minn. A small number also were found in Lake Huron in 1992. They could have moved through a small waterway between the two lakes or, more likely, were carried from one lake to the other in the ballast water of a commercial ship, according to the Fish and Wildlife Service.

Controlling the spread of fish not native to the Great Lakes has been a growing problem for the Fish and Wildlife Service. Asian carp that reach 4 feet and 100 pounds have been found in the Mississippi and in the Chicago Sanitary and Ship Canal, less than 30 miles from Lake Michigan. The round goby, zebra mussels and sea lampreys are other species not native to the Great Lakes whose populations scientists try to control.

- Fri, 9/6/2002

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