Kovac, V., 1997.  Biology of Eurasian Ruffe From Slovakia and Adjacent Central European Countries, Comenius University

Proceedings of the International Symposium on Biology and Management of Ruffe, March 21-23, 1997

Abstract
Geographical distribution, habitat requirements, reproductive biology, early development, diet, morphology, age and growth, and karyotype analysis of the European ruffe, Gymnocephalus cernuus, from Slovakia (Central Europe) are reviewed briefly. Several data from countries adjacent to Slovakia are also included. In Slovakia, the European ruffe prefers limnetic to lotic environment. It is a bottom-dweller that does not prefer any special substrate; however, it requires clean and well-oxygenated water. Males attain sexual maturity at a standard length of 32 to 80 mm, females at 57 to 90 mm. Ruffe are a polycyclic species with asynchronous ripening of eggs and protractive spawning. They spawn between mid-April and mid-June at water temperatures of 7.1 to 20.2^o C. Absolute individual fecundity is very variable, ranging from 1,000 to 150,000 eggs. The diameter of eggs varies from 0.97 mm to 1.07 mm. Embryos attain 3.35 mm to 3.81 mm at hatching. Ruffe feed mainly on larvae of chironomids, being active throughout the year, including winter. Most individuals attain the maximum age of 6 years, exceptionally 7 or 8 years, and maximum size of 15 cm, exceptionally 20 cm in total length. In the Danube, the abundance of ruffe ranges from 49 to 4,254 specimens/ha in side-arms, and from 378 to 14,934 specimens/ha in oxbow lakes. Ruffe are a prey species for large predators, such as pike and pikeperch. Fish eggs were not found in the stomachs of ruffe. Thus, the main impact of the species on local fish communities appears to be competition for food.

Contact: Vladimir Kovac, Comenius University, Faculty of Natural Sciences, Institute of Ecology, Mlynska dolina B2, SK-842 15 Bratislava, Slovakia
Keywords: Ruffe, Basic_biology, Population_dyanamics
Product Type: Publications, Conference_proceedings
User Type: General