Invasive fish species in rivers of the Western Bug basin within Ukraine

Purpose. To determine the occurrence of invasive fish species in ichthyofauna of rivers of the Western Bug basin in Ukraine. Methodology. Ichthiological studies were carried out during 2019-2021 in the Western Bug River and on its tributaries - Rata, Bushkov, Poltva and Mlynivka. Fish species identification was carried out in situ and was performed according to the identification keys of Yu.V. Movchan and A.F. Koblytska, incomplete biological analysis of invasive species was performed in the laboratory according to the methods of I.F. Pravdin, G.V. Nikolsky and I.I. Chugunova. Findings. The obtained data showed that invasive species in the composition of ichthyofauna in the studied rivers of the Western Bug basin were represented by five species: Prussian carp Carassius gibelio (Bloch, 1782), Stone moroko Pseudorasbora parva (Temminck & Schlegel, 1846), Pumkinseed Lepomis gibbosus (Linnaeus, 1758), Chinese sleeper Perccottus glenii Dybowski, 1877, Monkey goby Neogobius fluviatilis (Pallas, 1814). These species entered the ecosystem due to human activities through deliberate or accidental introduction into rivers of the Western Bug basin, where conditions are quite favorable for their vital activity and growth, due to a fairly warm climate and changes in hydrological regime of many rivers as a result of human impact. Originality. The article presents for the first time a list of invasive fish species of rivers of the Western Bug basin in Ukraine and provides a description of their habitats. Practical value. The obtained results can be used to regulate recreation fishery, for planning of conservation measures for rare fish species and for planning prevention of negative consequences from the spread of invasive fish species.