The second stage of the summer expedition in the Tsimlyansk Reservoir has been completed

 

The cruise was aimed at examining the most important spawning areas on the Chirsky, Potemkinsky and Priplotinny reaches of the reservoir, collecting samples for water hydrochemistry, food supply, assessing the productivity of juveniles and determining the efficiency of natural reproduction.

 

The scientific group of the vessel consisted of 7 specialists, including 4 ichthyologists, who examined 10 trawl catches and carried out work on 35 spawning areas using a fry drag. Samples of juveniles were sorted by species at the fishing site, their numbers were determined per spot and per unit area (1 ha).

 

In recent years, the species composition of juveniles and the efficiency of reproduction in the spawning grounds of the Tsimlyansk Reservoir have changed significantly. Due to the deterioration of conditions for natural reproduction of fish, a decrease in the yield of young fish is recorded for all fish species, with the exception of crucian carp. With a simultaneous decrease in the number of valuable commercial species, a dangerous increase in the number of low-value species is noted, which displace part of the Tsimlyansk ichthyocomplex, which is of greatest fishery value. The current state of the Tsimlyansk reservoir should be considered as a transitional stage between two stages of development - evolution and transformation, which it undergoes, like any other reservoir, obeying the laws of nature. This is indicated by changes occurring both in the habitat of aquatic organisms and in the composition of biotic communities. Naturally, the manifestations of these processes are most noticeable in the transition (ecotone) zone of water-land contact, covering the shallow waters of the Tsimlyansk Reservoir with depths of up to 3.0 m (occupying about 12-13% of the total area of the reservoir) and its drained coastal part, which can be considered as a special ecological zone for fish spawning and fattening of young fish.

 

The branch specialists collected the material. Within the framework of the program "Improvement of the Don River", work was carried out to survey the areas of natural spawning grounds of the Novotsimlyansk Bay in order to develop recommendations for improving their ecological state through fishery reclamation. Overgrowing of the Tsimlyansk Reservoir with higher aquatic vegetation (HAV), as the most important factor negatively affecting the conditions of natural reproduction, deserves special attention!

 

The collected material is being processed in the laboratories and scientific departments of the institute. Work using the research vessel in the Tsimlyansk reservoir will continue in the autumn period as part of the autumn trawl survey.

 

VNIRO Press Service