Dynamics of catches and state of stocks the European perch Perca fluviatilis in rivers in the middle Ob basin (in the Tomsk region)

Abstract

European perch Perca fluviatilis Linnaeus, 1758 — is a mediumsized representative of the Percidae. It distributed in lowland rivers, lakes and artificial reservoirs, as well as in desalinated coastal areas of the seas of Northern Eurasia, with the exception of the Far East and the coast of the Arctic Ocean. This species is numerous almost everywhere. It is one of the main objects of industrial and amateur fishing. In the Middle Ob basin, a significant part of the life cycle of perch is associated with the floodplain system. There is, during the spring flood, its spawning and subsequent feeding of juveniles and producers take place. Therefore, the regulation of the Ob’s flow by the Novosibirsk hydroelectric power station dam served as one of the important factors that had a negative impact on the state of its reserves. Thus, within the Tomsk region, commercial catches of perch before the regulation of the Ob flow (1946–1961) averaged 354 tons per year, and after regulation (during the period of stable fishing pressure, in 1960–1985) — 157 tons. In recent years (2018–2022), the catch of perch has increased slightly and, according to official fisheries statistics, amounts to 211 tons per year, providing 5.9% of the total fish production in the region. Currently, the reserves of perch are in a relatively stable state, the estimated indicators of its biomass in rivers within the Tomsk region in recent years range from 1190.9 to 2277.5 tons, with an average number of 10.6 million pieces. The development of the perch’ reserves is satisfactory, averaging 94.2% of the recommended catch. Amateur fishermen do not have a significant impact on the state of perch stocks.