Comparative analysis of the species composition of ichthyofauna of fish watering holes and adjacent channel areas of the Krasnoyarsk floodplain of the Volgograd reservoir

The Volgograd reservoir is a highly complex hydrological system. The locations of fish watering holes, which are situated in an abyssal area of the Volgograd reservoir, have been well established for a long time. Meanwhile, fish watering holes exist in areas of the bed of the Volgograd reservoir as well. However, their determination is not always possible and is complicated due to the small size and shallow depth of the watering holes. The aim of this work was to carry out a comparative analysis of the species composition of fish caught in watering holes and adjacent channel areas. The results might find an application in fish farming. The studies were conducted in the 2019–2020 winter season within Krasnoyarsk floodplain of the Volgograd reservoir. Floodplain length stretches some 26 km. The width of the Krasnoyarsk floodplain is 4–10 km. The depth of the Krasnoyarsk floodplain ranges from 0.1 to 10 meters. A bathymetric survey was conducted in order to validate data concerning the depths of fish watering holes. The current changes its direction periodically within the floodplain as a result of water passing by Saratov and Volgograd hydraulic structures, thus influencing the relief of the reservoir bed due to various locations of fish watering holes. The evaluation of the species composition of ichtyocoenosis was conducted using test fisheries and assessment of fish caught by recreational fishers. We assessed 19 fish species in the Krasnoyarsk floodplain of the Volgograd reservoir during the winter season using all fishing techniques. The conducted analysis of the Shannon diversity index within the watering holes and adjacent areas allows confirmation that all of the studied holes are active and serve as fish gathering places during the winter period. This study will allow the development of recommendations for the confirmation or revision of the status of fish watering holes in any subsequent study of bodies of water. That will facilitate the preservation of fish resources.