Assessment is an event carried out twice a year, in spring and autumn, necessary for assessing the condition of the aquatic bioresource stock, changes that have occurred with the fish kept during the period of rearing in fattening ponds (autumn assessment) or during the wintering period (spring assessment).
The autumn assessment of sturgeon species (assessment) is carried out when the water temperature drops and the fish stop feeding. Each fish is carefully caught, weighed, checked for physiological condition, clinically examined, changes in fish-breeding and biological parameters are noted, and, after treatment with special antiseptic agents, sent to the place of further maintenance.
During the grading process, fish farmers of the NEKA "BIOS" will determine the sex of fish from the middle and senior replacement groups, using a non-invasive method of ultrasound diagnostics, assess the degree of maturity of the gonads, samples are taken from females using special probes in order to determine the polarization coefficients of the oocyte nucleus. Fish individuals promising for the 2025 spawning campaign will be placed in the pools of the long-term aging workshop, where special conditions are maintained that contribute to the normal maturation of sexual products throughout the winter.
Along with the grading of the broodstock, the grading of senior replacements is carried out in order to select the most promising of the first maturing fish for spawners. This part of the fish will be the basis for artificial reproduction of Caspian sturgeon for many decades.
The other part of the fish is transferred for winter maintenance from summer ponds to wintering ponds, which are distinguished by greater depth and flow. Here the fish will survive the period of ice formation and low temperatures until spring.
Press service of VNIRO
