ICHTHYOFAUNA OF LOWER PART OF THE VRBANJA RIVER (THE REPUBLIC OF SRPSKA, BiH)

The diversity of freshwater ichthyofauna of Bosnia and Herzegovina (BiH) covers about 117 fish species/subspecies and makes up about 20% of European freshwater ichthyofauna. The Vrbanja River Basin is located in the central part of Bi and is one of the indigenous basins in the Republic of Srpska. The Vrbanja River is one of the largest right tributaries of the Vrbas River, with the lower part of the stream stretching for about 28 km. Ichthyological research of the lower part of the Vrbanja River was conducted during 2013, at three locations, and the sampling was performed with an electric fishing device ELT 62 II GI, 3 kW. The qualitative and quantitative compositions of ichthyofauna as well as some diversity indices (Simpson index, Shannon-Weaver index, Dominance index and Sørensen similarity index) were determined. The lower stream of the Vrbanja River is inhabited by 10 fish species belonging to three families (Cyprinidae, Cobitidae and Percidae). Family Cyprinidae is typified by the largest species diversity. The species dominant in terms of number of individuals and biomass were Barbus balcanicus and Squalius cephalus, which differ greatly from the ichthyofauna that inhabited the same area in the mid-20th century. This composition of ichthyofauna of the lower part of the Vrbanja River is related to the environmental factors and impact of certain human activities.