Fishes of non-floodplain lakes in the southern taiga of Western Siberia (in the Tomsk region)

Abstract

In the Tomsk region, the main fishing is concentrated on the Ob River and its large tributaries. At the same time, the region is rich in lakes — there are about 113 thousand of them with a total area of more than 4.5 thousand km². Of these, about 84 thousand reservoirs with a total area of about 2.9 thousand km² are lakes outside rivers floodplain — these are non-flood lakes. Mostly they are located in the taiga. They differ from each other in many parameters, including area, depth, ground, overgrowth of aquatic vegetation, and hydrochemical characteristics. Existing information about the fish of these lakes dates back to the mid-twentieth century and, against the backdrop of ongoing changes in the ichthyofauna of the region, seems outdated. During our research, we recorded 11 species of fish in non-flood lakes: northern pike Esox lucius, freshwater bream Abramis brama, common dace Leuciscus leuciscus, lake minnow Rhynchocypris percnurus, roach Rutilus rutilus, prussian carp Carassius gibelio, crucian carp C. carassius, tench Tinca tinca, ruffe Gymnocephalus cernua, european perch Perca fluviatilis, and chinese sleeper Perccottus glenii. Thus, over the past 60 years, changes have occurred in the ichthyofauna of non-flood lakes of the Tomsk region: there are alien fish species (naturalized in the Ob river basin) appeared — freshwater bream and chinese sleeper. Probably, in the near future we should also expect registrations of the belica Leucaspius delineatus and the Nikolsky loach Misgurnus nikolskyi, currently found in the Ob floodplain of the region. In addition, we did not observe ide Leuciscus idus in non-flood lakes; roach and common dace, which were relatively widespread in taiga lakes in the mid-20th century, were rarely encountered. Perhaps the decrease occurrence of these species is associated with climate change — the trend of increasing average temperatures which can cause a deterioration in the gas regime of water bodies.