THE INFLUENCE OF DAMMING ON THE DISTRIBUTION OF BROWN TROUT SALMO TRUTTA LINNAEUS, 1758 AND EUROPEAN GRAYLING THYMALLUS THYMALLUS LINNAEUS, 1758 (PISCES: SALMONIDAE) FROM SOME?UL CALD RIVER.

Monitoring fish fauna in altered aquatic habitats may provide relevant information regarding the distribution, presence or absence, and dynamics of fish species. Someşul Cald River is the main tributary of Beliş-Fântânele Reservoir and Dam, build from 1970 to 1974. The presence of the dam could have affected fish fauna, especially potamodromous brown trout Salmo trutta and European grayling Thymallus thymallus because of habitat obstruction. Altitude, riverbed width, water depth, and water velocity are easy to determine aquatic environmental parameters. River altitude and riverbed width played an important role in European grayling preference regarding the auspicious environment. Correlation coefficients showed that increasing altitude is a limiting factor for European grayling (r=-6024*, p<0.05). Wider riverbed is preferred by the same species (r=0.672*, p<0.05). Beliş-Fântânele Dam blocked the migration of fish and made the grayling ecological zone framed by two trout ecological zone (upstream and downstream). The distribution range on the altitude of the brown trout in Someşul Cald River was from 518.5m to 1153.5m and 577.5m to 1068.5m for the European grayling. [ABSTRACT FROM AUTHOR]