ПОРІВНЯЛЬНА ХАРАКТЕРИСТИКА ІХТІОФАУНИ РІЧКИ СТРИЙ ТА ДІЛЯНКИ ВЕРХНЬОГО І СЕРЕДНЬОГО ДНІСТРА

Abstract

The qualitative analysis of fish fauna of the Stryi River and the upper and middle sections of the Dniester River is conducted, and the taxonomy and faunistic structure are analyzed. The fish assemblage investigation was carried out during 2017–2020 in different seasons of the year. Fish sampling was performed by gill nets and sweep nets. Totally 15 locations were investigated and 465 specimens were caught.
 It has been established that the ichthyofauna includes 24 species in the studied section of the Upper Dniester and 22 species in the section of the Stryi River. The share of rare species is rather high: for the Dniester section, 33.3 % of the species listed in the Bern Convention and 12.5 % listed in the Red Book of Ukraine, and for the Stryi River, 40.9 % and 22.7 % respectively.
 The similarity of the Upper Dniester and the Stryi River ichthyofauna according to Shorigin was 53.9 %. The similarity of communities according to Jaccard was 0.59. Weinstein's index of biocenological similarity of ichthyocenoses in the studied rivers was low: 0.32. The low values of similarity indices are explained by the specificity of faunal structure in the studied rivers. Ichthyofauna of the Stryi and the Upper Dniester includes six ichthyocomplexes (boreal piedmont, boreal plain, tertiary plain freshwater, Pontocaspian freshwater, Pontocaspian marine, Chinese plain). The main similarities in the ichthyofauna of these rivers are formed due to the representatives of Pontocaspian freshwater, boreal plain and Chinese plain complexes: up to 72.7 % of total ichthyofauna.
 There has recently been an intensive advance of alien and invasive fish species into the piedmont of the Dniester River basin, which use transformed sections of the river with the silted bottom as refuges where they settle, increase in number and spread upstream. The share of alien species was rather high and amounted to 29.2 % in the Upper Dniester and 22.7 % in the Stryi River.