Factors contributing to the physiological disturbance in walleyes during simulated live-release angling tournaments

The goal of the current study was to examine the physiological disturbances in walleyes Sander vitreus that occurred during the different phases of a live-release angling tournament. To achieve this, we took blood and white muscle samples from walleyes during experiments that simulated different aspects of a live-release tournament (angling, live-well confinement, and weigh-in procedure). In accordance with recent findings for largemouth bass Micropterus salmoides, the physiological disturbance experienced by tournament walleyes results mainly from two distinct bouts of anaerobic metabolism occurring during angling and the weigh-in procedure. These periods are characterized by large increases in white muscle and plasma lactate concentrations, reductions in white muscle ATP, phosphocreatine, and glycogen and a significant cardiac disturbance. The physiological effects of angling are already well understood, but the physiological disturbance that occurs during the weigh-in procedure of tournaments has received little attention. In view of the results from our tournament simulations, a final set of experiments was conducted to examine more closely the bout of anaerobic metabolism experienced by walleyes during the tournament weigh-in. The results of these experiments showed that the magnitude of the physiological disturbance in tournament-caught walleyes is directly related to the duration of air exposure occurring during the weigh-in. Based on these findings, we suggest that to reduce the physiological disturbance experienced by tournament-caught walleyes, tournament organizers should strive to minimize air exposure during the weigh-in procedure.