Ruff
| Ruff | ||||||||||||
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Ruff ( Gymnocephalus cernua ) |
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| Scientific name | ||||||||||||
| Gymnocephalus cernua | ||||||||||||
| ( Linnaeus , 1758) |
The rufffish ( Gymnocephalus cernua ) is a brackish and freshwater fish from the family of the real perch (Percidae) that is widespread in Central and Eastern European rivers and the Baltic Sea .
distribution
It occurs in Europe north of the Pyrenees (exposed in western and central France) and the Alps in rivers that flow into the North Sea , Baltic Sea , White Sea , Barents Sea , Black and Caspian Sea , as well as in lakes in the catchment area of these rivers. He also lives in England (not in Scotland and Wales ) and in Siberia in rivers that flow into the Arctic Ocean (east to Kolyma ). It is absent in the Balkans south of the Danube and in western Norway, but is also at home in the brackish water of the Baltic Sea. The ruff was introduced by humans into the North American Great Lakes .
features
The ruff usually reaches a length of 12 to 15 cm, the maximum length is 25 cm, the maximum weight 400 g. Its body is somewhat high back, the body height is 24 to 27% of the standard length , and covered with comb scales. The gap in the mouth is as long as the diameter of the eyes or slightly shorter. The gill cover has a long, strong spine, the gill cover several short spines. On the underside of the head there are flat, round mucous pits that can perceive movement stimuli in addition to the lateral line organ . In contrast to the perch ( Perca fluviatilis ), the dorsal fin of the ruff is undivided. The number of vertebrae is 35 to 36. Rufffish are olive-brown to gray-green in color and covered with dark, irregular spots, the flanks are yellowish. The chest shimmers reddish, the belly is whitish or light green.
- Fin formula : dorsal XII – XVI / 11–15, anal II / 5–6, caudal 16–17.
- Scale formula : 35–40 (mLR)
Way of life
The ruff lives in small groups of nutrient-rich, stagnant or slow-flowing waters, especially regions with a sandy bottom, and is quite insensitive to water pollution . It is most common in the mouths of large rivers and in brackish coastal regions with a salt content of up to 12 ‰. When it occurs together with the perch, the ruff prefers deeper water layers. It feeds on zooplankton , mosquito larvae , worms, amphipods and fish spawn as well as fry. Thanks to its well-developed sideline system, it can also hunt in the dark. Ruff spawn from March to May. Depending on the size of the females, 50,000 to 100,000 yellowish white eggs are laid in gelatinous strings or clumps on stones, less often on aquatic plants. The larvae hatch after 8 to 12 days. Females live to be ten years old, males seven.
etymology
Linnaeus described the species (after Artedi ) as Perca cernua , Bloch established the genus Acerina , which is younger than Gymnocephalus ( Greek for “naked head”). The epithet cernuus (Latin) means “upside down, doing somersaults, dancing”. Kottelat and Freyhof argue that cernua should be taken as a noun - it means “perch that digs a lot upside down”, hence Gymnocephalus cernua .
literature
- Fritz Terofal: Steinbach's natural guide, freshwater fish. Ulmer, Stuttgart 2003, ISBN 3-8001-4296-1 .
Individual evidence
- ↑ invasivespeciesinfo.gov
- ↑ Maurice Kottelat, Jörg Freyhof: Handbook of European Freshwater Fishes. ISBN 978-2-8399-0298-4 .
Web links
- Ruff on Fishbase.org (English)
- Gymnocephalus cernua inthe IUCN 2013 Red List of Threatened Species . Posted by: Freyhof, J. & Kottelat, M., 2008. Retrieved January 11, 2014.