RUFFE FROM THE FORMER USSR - VARIABILITY WITHIN THE LARGEST PART OF ITS NATURAL RANGE

This paper reviews current data on the ruffe, Gymnocephalus cernuus L. , its range, variability of its meristic and morphometric characters, diet composition and trophic relationships, habitats, behavior, growth , reproduction, and abundance. Ruffe, a monotypic species, is found fr om the Baltic Sea to the Kolyma River. Recent evidence extends its dis tribution as far as the Arctic coast both in Europe and Asia. In the s outh, the range is restricted by the Caucasus in Europe, and in Asia b y the Aml Sea basin and upper reaches of several large Siberian rivers . Ruffe usually have a narrow home range. Their seasonal migrations ar e related mainly To reproduction. In lakes and reservoirs, ruffe are f ound everywhere from shallow to the deepest zones. In rivers, they pre fer sites with slow current. Ruffe show flexible foraging, breeding, a nd migratory behavior. Adults compete with common bream, roach, and be nthivorous whitefishes, and are the prey of pikeperch, burbot, pike, l arge perch, and eel. The age of maturation is similar (2 to 3 years, s ometimes I year) from the northern to southern areas. Fecundity tends to increase from north to south. Daily specific growth rate is rather constant everywhere; the fastest growth was observed in the newly-impo unded reservoirs. Ruffe variability to a larger extent depends on loca l ecological situations rather than on latitudinal factors. Attempts t o control ruffe populations with small-mesh seines were unsuccessful a nd only caused a reduction in average age of populations. Introduction of some piscivorous fishes (eel, pikeperch) was more efficient.