MORPHOPHYSIOLOGICAL PARAMETERS OF SOME STURGEON SPECIES (ACIPENSERIDAE, ACIPENSERIFORMES) OF DIFFERENT AGE GROUPS REARED IN AQUACULTURE

Purpose. To study some morphometric parameters, protein and lysozyme content in organs and serum in several sturgeon species reared in aquiculture at the ages of 3, 8 and 18 months, and to investigate the specific and age distribution of lysozyme in fish organs. Methodology. For the experiments we used sturgeon species of different age groups reared in the fish farm ?Fortuna XXI? located in the Galerny Gulf of the Dnepr river. The study objects were: bester (Huso huso×Acipenser ruthenus), age of 3, 8 and 18 months; Russian sturgeon (Acipenser gueldenstaedtii), age of 3 months, Siberian sturgeon (A. baeri) and sterlet (A. ruthenus), age of 8 month. Following morphometric parameters were determined in the studied fish: weight (g), length (cm), absolute weight of liver, kidneys, spleen (mg), condition factor and relative weight (index, ‰) of organs. The lysozyme content was determined in serum and extracts of the tissues of fish organs by a diffusion method on the agar and protein content was determined by Louri's method. Findings. We detected significant differences in morphometric parameters, protein and lysozyme content in organs and serum of 3-month bester and Russian sturgeon as well as specific differences of relative organ weight, protein and lysozyme levels in organs and serum of 8-month Siberian sturgeon, bester and sterlet. A comparison of the investigated parameters in 3, 8 and 18-month bester showed an increase in the condition factor with fish growth, significant changes of protein content in fish of different age groups, high level of lysozyme in kidneys and serum of 18-month fish, redistribution of lysozyme contents in fish organs depending on age. Originality. First comparison of several morphophysiological parameters of 3, 8, 18-month sturgeon species (sterlet, Russian sturgeon, Siberian sturgeon, bester) reared in aquiculture. Practical value. Taking into account the high commercial value of sturgeon species, the conducted studies showed that in the conditions of cage culture with the use of live and high quality granulated feeds, juveniles and age 2 commodity sturgeons maintain the high level of general nonspecific immunity inherent to sturgeon species living in natural conditions.