ICHTHYOFAUNA OF THE UPPER SAN DRAINAGE BASIN
Academy of Agriculture in Cracow, Department of Economics in Rzeszów
ABSTRACT. Ichthyofauna of the upper San drainage basin was studied in 1993-1999, at 50 sampling sites. Fish were sampled using electric gear, and a questionnaire survey was carried out. Seventeen fish species were observed. Spotted sculpin (Cottus poecilopus Heck.), brown trout (Salmo trutta m. fario L.), and minnow (Phoxinus phoxinus (L.)) showed the highest stability index. Spotted sculpin, minnow, brown trout, chub (Leuciscus cephalus (L.)), bearded stone loach (Barbatula barbatula (L.)), and Balkan barbel (Barbus meridionalis petenyi Heck.) predominated in the samples. Fish community composition of upper San drainage basin was similar to that observed in most Carpathian Vistula headwaters. In brown trout population, young individuals predominated. Grayling (Thymallus thymallus (L.)) was found at 17 sampling sites, and extended its area to Bieszczady Mountains. Riffle minnow (Alburnoides bipunctatus (Bloch)) was one of the rarest species.
Key words: FISH, MOUNTAIN STREAMS, BIESZCZADY MOUNTAINS