Assessment of the state of aquatic bioresources and the feasibility of involving floodplain lakes of the Ob river in the upper reaches of the Novosibirsk hydroelectric power station in fishing

Abstract

An overview of typical lakes of the floodplain system of the river is presented. Ob in the upper reaches of the Novosibirsk hydroelectric power station. Data on the species structure, abundance and biomass of zooplankton, zoobenthos and fish are presented. Most of the lakes of the left-bank floodplain of the Ob have an elongated channel-like shape and a constant hydrological connection with the channels of the Ob river. The lakes are located in a low floodplain and are completely flooded by flood waters even in low-water years. The area of the lakes does not exceed 40 hectares. The zooplankton of the lakes is represented by 16 species, the total number varied from 360 copies/m3 (lake Epanchino) to 36 530 copies/m3 (lake Komendantskoye), the biomass was 13.8–229.0 mg/m3. According to the development of zooplankton, all the floodplain lakes studied belong to low-feeding, ultra-oligotrophic type reservoirs, the lowest productivity class. 13 species were found in the zoobenthos of floodplain lakes, the total number varied from 172 specimens/m2 (lake Chernoe) to 860 specimens/m2 (lake Baigachevskoe), biomass — from 0.513 to 4.196 g/m2. On the development of zoobenthos lake. Epanchino refers to medium–fed, mesotrophic type reservoirs, the other three — to low-fed, oligotrophic type reservoirs, low productivity class. The main species of ichthyofauna of floodplain lakes are pike (Esox lucius Linnaeus), river perch (Perca fluviatilis Linnaeus) and silver carp (Carassius gibelio Bioch). Pike at the age of 3+ — 4+ years dominates in lake populations, perch — 2+ years. The biomass of the ichthyofauna is 15,3–45,8 kg/ha. According to the ichthyomass, floodplain lakes of the lower reaches belong to the oligotrophic and mesotrophic type of reservoirs, low and medium productivity class.