ICHTHYOFAUNA OF THE BUGAZ RIVER IN THE UPPER IRTYSH BASIN AND THE CURRENT STATE OF FISH POPULATIONS

Abstract

The article analyzes the composition of the ichthyofauna of the Bugaz River in the Upper Irtysh basin and the population status of fish species. The study was conducted based on materials collected in 2005, 2023, and 2024 using standard ichthyological methods. During the morphometric analysis, body length and weight of fish were measured, Fulton’s condition factor (K) was calculated, and the data were processed using descriptive (univariate) statistical methods. The study identified 9 fish species belonging to the order Cypriniformes in the Bugaz River: dace, Altai minnow, Balkhash minnow, gudgeon, roach, spotted stone loach, gray stone loach, weatherfish and Siberian weatherfish. The results demonstrated the predominance of native species in the ichthyofauna. Among the recorded species, roach is an introduced species, and no invasive species were detected. In the 2005 samples, parasitic flatworm infection was recorded in some individuals of the spotted stone loach (Triplophysa strauchii), indicating a weakened physiological condition of the population during that period. The results of the 2023–2024 studies showed relative stabilization of trophic conditions in the water body and no signs of parasitological infection.

Keywords: ichthyofauna, morphometry, Fulton’s condition factor, native species, introduced species, Cyprinidae, Nemacheilidae, Cobitidae.