Length-based harvest restriction is common in fisheries management and can result in a substantial number of fish being released after capture. Science on live release confirms that the practice allows individuals to return to the population and reproduce; however, little is known about how handling practices influence mortality or the sub-lethal physiological alterations in fish that are released during the winter. In this study, walleye (Sander vitreus; Mitchill 1818) were angled through the ice in Lake Nipissing, Ontario to evaluate the contribution of air exposure to the reflex impairment, post-release mortality, and the stress response of fish in the winter. Following 24 h holding, fish were exposed to a simulated angling event and exposed to air or snow across a range of exposure durations. Fish were non-lethally blood sampled and were assessed for reflex impairment and mortality 24 h after capture. No mortalities were recorded during the study and reflex impairment was not linked to exposure type or duration. Blood [lactate] at 1 h post-capture was comparable across treatment groups but was significantly higher than respective baselines. Plasma [cortisol], blood [glucose], and aspartate aminotransferase activities were comparable to baseline levels. Walleye appeared to be resilient to catch-and-release angling in the winter given that no mortalities occurred and fish suffered minimal reflex impairment and physiological disturbance following capture. Findings from this study suggest that mandatory catch-and-release regulations for sub-adult walleye are a useful tool for the management of winter walleye ice fisheries.

Catch-and-release, Mortality, Recreational fishing, Sander vitreus, Stress, Teleost, Walleye, Winter
Fisheries Research
Department of Biology

Logan, J.M. (James M.), Lawrence, M.J. (Michael J.), Morgan, G.E. (George E.), Twardek, W.M. (William M.), Lennox, R.J. (Robert J.), & Cooke, S.J. (2019). Consequences of winter air exposure on walleye (Sander vitreus) physiology and impairment following a simulated ice-angling event. Fisheries Research, 215, 106–113. doi:10.1016/j.fishres.2019.03.014