The greatest reduction in the area of spawning grounds is observed in the southern areas, where, on the one hand, the influence of the Volga runoff is practically unaffected, and on the other hand, there are unfavorable phenomena of shallowing and drying out associated with the continuing drop in the level of the Caspian Sea.
A reduction in the area of spawning grounds with a drop in sea level occurs on the shore side, and simultaneously with the expansion of the thicket zone, the spawning grounds are shifting towards the sea. Specific hydrometeorological conditions in spring and early summer affect the efficiency of natural reproduction of aquatic biological resources. When driven by winds, the area of spawning grounds increases, and when driven by winds, it decreases; the death of laid eggs and early larvae on drained areas of spawning grounds is possible.
The efficiency of natural spawning of commercial fish was assessed based on control fishing of juveniles in June-July at 7 observation stations. The fishing was carried out using a fry drag net; the catching area per operation was 30 m2. At the same time, observations were made of habitat conditions at fish spawning sites: water depth and transparency, permanganate oxidation, mineralization and oxygen content, water temperature and wind direction.
According to preliminary observation results, in 2024 the area of spawning grounds in the southern regions adjacent to Darginsky Bay continues to decline. The flooding of spawning grounds was short-lived, and no fish kills were observed. On river floods Kuma and at its mouth a high concentration of juvenile silversides is noted. At the spawning grounds of the northern region on the border with the Astrakhan region, near the village of Voskresenovka, there is a noticeable drop in water level from June to July.
VNIRO press service