Physiological Stress Response of Yellow Perch Subjected to Repeated Handlings and Salt Treatments at Different Temperatures

Yellow Perch Perca flavescens were subjected to handling stress and salt treatments at different temperatures to determine their physiological changes. Yellow Perch, held at 8–10°C, were divided into three groups with four replicates and subjected to water temperatures of 14, 20, and 26°C to acclimate. Then they were subjected to acute handling twice within separate intervals, in addition to a salt treatment at a salinity of 5‰ for each of the fish groups. Plasma cortisol was used as a stress indicator, and blood samples were taken periodically for plasma cortisol concentration analysis. An increase in plasma cortisol after handling occurred in all groups, but the lowest level of plasma cortisol was in fish subjected to 20°C. We concluded that the optimum water temperature for handling Yellow Perch that results in minimal stress may be 20°C. Salt treatment after handling further stimulated the stress response and increased plasma cortisol levels. Research is needed to identify the optimal salinity to use for Yellow Perch and other fish species when handling fish during common aquaculture practices.