Investigation of the physiological state of the Caspian common sprat in spring

Abstract

The aim of the work was to assess the physiological state of the common sprat in the spring period near the Dagestan coast of the Caspian Sea. The study of individuals was carried out according to a set of biological indicators. The mass, length were determined, and the Fulton fatness coefficient was calculated. The stages of maturity of fish gonads were determined, the morpho-functional state of gonads and gills was assessed by histological methods. The content of total lipids and water-soluble protein were analyzed in the muscles. In March, females were predominantly marked III stage of gonad maturity, in April — IV stage of gonad maturity. In the spring period, diffuse resorption of mature oocytes was recorded at an average level of 27–28%. In males, IV–V, VI–V stages of testicular maturity were recorded. In April, a decrease in the content of total lipids and the Fulton fatness coefficient (p < 0.05) was registered relative to March, which is associated with the expenditure of the body’s energy on the maturation of gonads in portion-spawning common sprat. The concentration of water-soluble protein in sprat muscles in March and April was comparable. Local vascular disorders and the presence of mucosal cells were recorded in the structure of the gills. The revealed morphological disorders characterized the adaptive capabilities of the organ to the external influences of the habitat. According to the results of the studies conducted in the spring of 2022, the physiological condition of the Caspian common sprat was satisfactory. The results obtained are of great importance for predicting the development of the fishery for this species near the Dagestan coast of the Caspian Sea.