This work is conducted annually by the Southern Branch of the SSC RF "All—Russian Research Institute of Fisheries and Oceanography" (VNIRO), the only institution that systematically evaluates the effectiveness of natural fish reproduction in one of the main waterways of Southern Russia.
This year, the expedition work on the Don took place from the beginning to the middle of August — the time was chosen deliberately: by this time, the juveniles of most commercial species have reached the necessary vitality. In the Azov‑Black Sea basin, an individual weighing 3-5 g is considered such — it is this type of weight that juveniles usually gain by the end of summer. The research covered the area from the mouth of the Don to the Kochetovsky hydroelectric power plant: scientists carried out seine surveys on both banks every 10 kilometers and trawling with a seine trawl along the riverbed — this approach gives a complete picture of the distribution of juveniles.
In addition to accounting for juveniles, the specialists collected a set of data on their habitat conditions: they studied the components of the food supply (phytoplankton, zooplankton and zoobenthos), and also took samples of water and soil for chemical analysis, including the content of nutrients, heavy metals, petroleum products and environmental toxicity. All materials have been transferred to the branch's specialized laboratories for processing and analysis.: This will allow not only to count the young, but also to assess whether they have enough food and how safe the environment is.
Preliminary results indicate a low spawning efficiency this year, which is associated with a prolonged cold spring. The final conclusions about the yield of juveniles will be formulated after the analysis of the collected data is completed.
VNIRO Press Service
