Scientific name- Gymnocephalus Cernuus

The Eurasian ruffe is another nonnative species in America. The fish came to America from Eurasia by getting into the ballast, the part of a ship that carries sand or iron to keep the ship stable.

Ruffes cause problems to many species of native fish. Where ruffes are located, populations of native fish have gone down. Ruffes have skeletal features that let them know when either a predator that hurts the ruffe or prey that is eaten by the ruffe is near. This helps the ruffe spread, but it doesn’t help other animals because they are so easily found. The results of this can lower numbers of native species. Ruffes hurt other species by eating other native fish so rapidly.

The ruffe has pointed dorsal fins on its back. Its average length is 4 to 6 inches but the maximum is 10 inches. The ruffe’s mouth is turned down, and it doesn’t have scales on its head. This makes it look different from its relatives, the yellow perch and the walleye.

One thing that Upper Midwest Environmental Sciences Center (UMESC) scientists are doing to stop the ruffe is trying to find a chemical that will kill the ruffe but also leaves other fish alone. They already have some chemicals registered to kill the ruffe, but they don’t know if the chemicals will kill other fish. Since UMESC scientists have already found a chemical that will kill the sea lamprey, they have high hopes that they will find one to kill the ruffe.

Although scientists are trying to kill numbers of nonnative species, there are still some that are causing problems for other animals and plants. Scientists have not tried to kill every nonnative species because they are not as big of a problem, but they could become a problem for animals and plants soon. Scientists may use chemicals or beetles to stop the growth of these nonnative species. If no one stops these invading species, we will not have many fish from North America in our lakes and many animals and plants in our fields.

Click on the "Introduction" button below to see the bibliography for this page and more information on nonnative species.