Date of this Version
Loomis, J., H.L. Schramc, B. Vondracek, and C. J. Chizinski. 2013. Effects of simulated angler capture and live-release tournaments on walleye survival. Transactions of the American Fisheries Society, 142:868-875.
We examined the effects of acclimation water temperature, live-well (LW) water temperature, and LW dissolved oxygen (DO) concentration on survival of adult Walleyes Sander vitreus subjected to simulated tournament conditions (angling, LW confinement, and weigh-in procedures) under controlled laboratory conditions. We tested three acclimation temperatures (12, 18, and 24◦C), and three LWtemperature differentials (Delta T=−4, 0, and +4◦C) were tested at each acclimation temperature. Survival was monitored after 8 h of LW confinement and during a 5-d retention period in 1,700-L tanks. None of the Walleyes that were acclimated to 24◦C and subjected to simulated tournament procedures survived the 5-d retention period; for fish subjected only to simulated angling at 24◦C, survival during the 5-d retention period was 29%. Five-day survival was generally over 70% at acclimation temperatures of 12◦C and 18◦C, and we observed a significant interaction between acclimation temperature and Delta T; survival was greatest in LWs at −4◦C Delta T for fish acclimated to 18◦C and in LWs at +4◦C Delta T for fish acclimated to 12◦C. Best survival of Walleyes subjected to the stress of angling and tournament procedures was obtained at temperatures 6–8◦Cbelow the optimum temperature for adult Walleyes (i.e., optimum = 20–22◦C). Five-day survival exceeded 70% when LW DO was 5 or 12–15 mg/L (at an acclimation and LW temperature of 18◦C), but survival was 0% when DO was 2 mg/L. Anglers may increase survival of Walleyes through careful manipulation of LW temperature and DO when ambient temperature is at or below 18◦C, but high mortality of angled and LW-retained Walleyes should be expected when ambient water temperatures are 24◦C or greater.
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