Effects of variation of holding temperature on physiological and biochemical parameters of juvenile sturgeon fish in the conditions of industrial breeding

Abstract

Below are presented the results of physiological stress (sudden temperature variations) affecting the physiological and biochemical parameters of juvenile sturgeon fish (sterlet and Siberian sturgeon) in the conditions of industrial breeding. They show that the temperature variations in the range of ±15 °С at the rate of 5 °С/hour towards temperature decrease are reversible physiological stress for physiologically healthy starving juvenile sturgeons, with which the species cope well if corresponding adaptation mechanisms are used (100 % survival rate). According to the examined physiological and biochemical parameters, the temperature variation towards decrease has its impact on the respiratory frequency (if the temperature decreases by 5 °С during the first hour of exposure, it increases by 30 % from the initial frequency; in three hours of exposure it decreases by 15 % from the initial frequency if the temperature decreases by 15 °С) and blood glucose level which increases by 15, 30 and 50 % every hour of exposure. The same temperature variations towards increase lead to irreversible physiological changes accompanied by the manifestations of acute stress reaction and death of juvenile fish depending on the severity and duration of temperature stress. During the first hour of exposure, the respiratory frequency increases twice, during the second hour it increases 2.5-fold, and 3-fold during the third hour. Blood glucose level increases by 10% during the first hour, twice during the second hour, 3-fold during the third hour from the initial level. Blood lactate level increases 5-fold from the initial level between the second and the third hour of exposure. Acute stress reaction beyond the adaptive capabilities manifests itself as a drop in fish survival rate in the second or the third hour of temperature increase, from 80-90% to 0% of general fish quantity in the experiment respectively.