FISH ASSEMBLAGES IN THE SŁUPIA RIVER SYSTEM (NORTHERN POLAND)
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. Electrofishing was carried out at 66 sites in the Słupia River system. Twenty-five fish species were noted. The most frequent were trout (Salmo trutta), three-spined stickleback (Gasterosteus aculeatus) and bullhead (Cottus gobio). Three groups of sampling sites were distinguished based on fish densities and species composition. These fish assemblages inhabited places that did not differ widely with regard to the 13 environmental parameters assessed. Although there were also no clear sequences of assemblages, the distinct influence of lakes and impoundments was evident.
Key words: RIVER, ICHTHYOFAUNA, FISH DISTRIBUTION
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