Researchers have found evidence of a small invasive fish in southern Lake Michigan for the first time. It could be an early warning that the species may be spreading and could migrate into the Mississippi River system.
The Eurasian ruffe entered the northern Great Lakes 25 years ago in the ballast water of a ship in Duluth harbor.
Two DNA samples recently found in southern Lake Michigan may also come from ballast water or from scales or waste, not necessarily from a live fish. But researchers see this as warning sign since the ruffe prefers warmer shallower water and thrives in river systems.
If it’s in southern Lake Michigan, the perch-like species could migrate through Chicago waterways to the Mississippi River and it could compete with native perch and walleye.
The U.S. Army Corps of Engineers is studying ways to permanently close waterways between the Great Lakes and the Mississippi, mainly to stop Asian carp from reaching Lake Michigan.