Effects of Simulated Angler Capture and Live‐Release Tournaments on Walleye Survival

Abstract

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 LW temperature differentials (ΔT = −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 ΔT; survival was greatest in LWs at −4°C ΔT for fish acclimated to 18°C and in LWs at +4°C ΔT 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°C below 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.

The Effect of Water Temperature, Angling Time, and Dissolved Oxygen on the Survival of Largemouth Bass Subjected to Simulated Angling and Tournament Handling Procedures

“…This is in sharp contrast to substantially reduced survival of Walleyes subjected to 1 min of simulated angling at 24°C (2–4°C above preferred temperature; Loomis et al. ). Thus, unlike Walleye fisheries, catch and immediate release can be expected to cause minimal mortality of angled Largemouth Bass when the fish are landed quickly and handled carefully.…”

“…In this study, fish that were subjected to 1 min of simulated angling and that were handled quickly and carefully before release had 100% survival at water temperatures up to 33°C (4-7°C above preferred temperature ;Coutant 1977;D ıaz et al 2007), which approximates the maximum water temperature encountered in most Largemouth Bass fisheries. This is in sharp contrast to substantially reduced survival of Walleyes subjected to 1 min of simulated angling at 24°C (2-4°C above preferred temperature; Loomis et al 2013). Thus, unlike Walleye fisheries, catch and immediate release can be expected to cause minimal mortality of angled Largemouth Bass when the fish are landed quickly and handled carefully.…”

“…Loomis et al. () found that catch‐and‐release angling caused high mortality of Walleyes at 24°C, a water temperature that is only 2°C greater than their preferred temperature and that is frequently encountered in Walleye fisheries. This finding, if applied to Largemouth Bass fisheries that are primarily catch and release (Quinn ), would have a significant impact on populations, estimates of exploitation, and population modeling efforts.…”

“…To date, only one study has conducted experiments testing the independent effects of water temperature and DO on the survival of angled and tournament‐handled freshwater fish (Walleye Sander vitreus ; Loomis et al. ).…”

“…Although these studies have provided useful information needed to advance catch-and-release science, controlled experiments testing for the independent effects of important environmental variables on survival of angled fish-namely water temperature and live-well dissolved oxygen (DO) concentration-are limited. To date, only one study has conducted experiments testing the independent effects of water temperature and DO on the survival of angled and tournament-handled freshwater fish (Walleye Sander vitreus; Loomis et al 2013).…”