A Review of Ruffe Gymnocephalus cernuus Life History in Its Native vs. Non-Native Range

Invasive Ruffe (Gymnocephalus cernuus) have the potential to cause negative impacts in introduced streams, rivers, lakes, and estuaries.  The objective of our study was to define Ruffe native and non-native ranges and to examine their life history requirements to better predict suitable habitat and ecological impacts.  Their native range extends from eastern Scandinavia in the north to the Danube River and Black and Caspian Seas in the south and from western Siberia to the east and the Netherlands to the west.  Ruffe have established populations in Italy, England, Scotland, Wales, Germany, Norway, and the U.S.  The life history requirements of Ruffe vary among life stages and between the native and non-native range.  For example, Ruffe live in shallow, warm water as larvae; whereas, they live in deep, cool water in later life stages.  In the native range, they primarily eat chironomids, whereas in their non-native range, food items include zooplankton, caddisflies, mayflies, Mysis, and fish eggs.  Adult Ruffe age at maturity, reproductive behavior, feeding habits, and movements allow them to readily adapt to novel environments.  We conclude that all of the Great Lakes and many other regions in the U.K., Europe, and Scandinavian countries are vulnerable to a Ruffe invasion.