Assessment of the accuracy of physiological blood indicators for the evaluation of stress, health status and welfare in Siberian sturgeon (Acipenser baerii) subject to chronic heat stress and dietary supplementation

International audienceThere is growing interest in the evaluation of stress, health and welfare of farm-raised fish. However, there is no scientific consensus about the methodology that is used to assess them. Sturgeon aquaculture is a recent industry with increasing interest in the production of caviar, which is characterized by high turnover and costs. To improve aquaculture efficiency, this study was conducted on routine blood samples, taken from Siberian sturgeon (Acipenser baerii), to test the robustness of using only physiological indicators to assess heat stress, health, and welfare. Sampling was performed after 1 month of prebiotic dietary supplementation followed by 4 weeks of sublethal heat stress. Data interpretation was achieved with a multivariate statistical tool. The expression of heat shock proteins (HSP) was assessed for the first time in sturgeon erythrocytes. Hsp70 and hsp90 expression was triggered by both stress and dietary supplementation. Indicators of non-specific immunity were modified mainly by stress. Complement activity increases with stress while lysozyme activity decreases, but to a lesser extent in supplemented fish. The antioxidant capacity increases with stress while oxidant metabolites decrease and overall oxidative stress was lower for fish that received dietary supplementation. The positive impact of dietary supplementation on health status was observable after a stress challenge. A principal component analysis was used to combine all the measured parameters and to observe patterns in physiological fish status. The four experimental groups of fish were clearly discriminated with this statistical tool. Physiological indicators from blood samples may enable heat stress, health, and welfare to be assessed in Siberian sturgeon