Ruffe
Ruffe - (Gymnocephalus cernuus)
Length: 4 to 6 inches(25 cm)
Coloring: olive-brown to golden-brown on back, paler on the sides with yellowish white undersides
Common Names: Eurasian ruffe, river ruffe, pope
Found in Lakes: Huron and Superior
The ruffe is a small but aggressive fish native to fresh and brackish
waters in portions of Eurasia. It was introduced into Lake Superior's
Duluth/Superior harbor area in the mid-1980s in the ballast water of an
trans-oceanic ship.
In Europe, the ruffe generally matures and begins to reproduce in two
or three years, but it may mature in one year in warmer waters. It spawns
between mid-April and July, depending on location, water temperature and
preferred years. An average female can produce 130,00 to 200,000 eggs
per season.
A relative of the perch, the ruffe spends its days in deeper water and moves to the shallows to feed at night. Ruffe in the Great Lakes seem to be most common in or near river mouths. To avoid predators, the ruffe prefers darkness, and uses special sensory organs called "neuromasts" to detect predators and prey. The ruffe also has a large, spiny dorsal fin likely unpalatable to predators.
Because the ruffe grows very fast, has a high reproductive capacity and adapts to a wide variety of environments, it is considered a serious threat to commercial and sport fishing. It also has the potential to seriously disrupt the delicate predator/prey balance vital to sustaining a healthy fishery.
Local laws vary regarding the possession of ruffe. Take a look at your state or province regulations, and contact your local authorities if you need more information.
copyright 2001 University of Wisconsin Sea Grant Institute
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