Physiological responses of walleyes to live-release angling tournaments

This study examines the physiological impacts of live-release angling tournament practices on walleyes Sander vitreus (formerly Stizostedion vitreum). Blood and white muscle samples were taken from walleyes following the weigh-in at several live-release angling tournaments in southern Ontario. The tournament walleyes had significantly elevated plasma cortisol levels in comparison with those of the control walleyes, indicating that tournament practices elicit a significant stress response in the tournament fish. Increased creatine phosphokinase and lactate dehydrogenase activities revealed that walleyes experience a moderate degree of cellular damage during live-release angling tournaments. In contrast to recent research with largemouth bass Micropterus salmoides, the tournament walleyes showed evidence of plasma ion loss. The tournament walleyes also experienced dramatic reductions in white muscle energy stores (phosphocreatine, ATP, and glycogen) and corresponding increases in plasma and white muscle lactate levels when compared with those of the control fish. These metabolic changes were similar in magnitude to the changes previously observed in largemouth bass following tournaments and suggest that current tournament procedures may commonly cause relatively large bouts of anaerobic metabolism in fish