Results of ichtiological studies in the deep-water section of the Yellow River — a potentially possible winter pit

Abstract

Wintering pits of semi-passable and river fish on the Lower Volga have historically had a protected status that prohibits any fishing in their waters. The wintering period is important in the life of semi-migratory and river fish, and directly affects the formation of their stocks. The process of pit formation in the Volga Delta is continuous. At the same time, some of the pits lose their fishing significance over time, while others, newly formed, on the contrary, have mass accumulations of fish, especially in the pre-winter and winter periods. The aim of the work was to study the structure of the fish population in the deep-water section of the river-a potential wintering pit. The seasonal and spatial dynamics of the species composition of the fish population, their concentrations in the pit and in the adjacent riverbed are shown. It is noted that the studied area is a typical wintering pit of the Volga river Delta, where common catfish Silurus glanis (Linnaeus, 1758), carp Cyprinus carpio carpio (Linnaeus, 1758) and walleye Sander lucioperca (Linnaeus, 1758), which form the basis of research (control) catches (more than 90%), lie for the winter. High indicators of the relative number of fish were observed throughout the study period, which indicates a high productivity of the deep-water object, in terms of the formation of pre-winter and winter concentrations, which is associated with favorable conditions for wintering semi-passable and river fish (depth, flow rates, etc.). The Pit meets the developed ichthyological criterion and is a place of mass concentrations of fish suitable for wintering. In order to preserve and restore the resource potential of the Lower Volga, the winter pit on the Yellow river should be recommended for inclusion in the List of winter pits of the fishing Regulations for the Volga-Caspian fisheries basin (Astrakhan region). The protected status of the site will allow you to remove the winter pit from the fishing zone, including Amateur fishing, preventing its looting in the future

Winter refuge for freshwater fish

“…According to the researches of many authors, it has been noted that certain characteristics of the depth and near-bottom current velocities are fundamentally necessary conditions for the habitat of fish in the winter. [10,29,34]. Using the example of sturgeons, it was shown that [10] both depth and near-bottom flow velocity are important predictors of the choice of habitat for wintering fish.…”