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.

Received November 12, 2012; accepted March 7, 2013

ACKNOWLEDGMENTS

This project benefited from the contributions of numerous individuals. Personnel from the MNDNR collected and transported Walleyes for the project. Funding for the study was provided by FLW Outdoors; the Iowa Department of Natural Resources; the Michigan Department of Natural Resources; MNDNR; the South Dakota Department of Game,Fish,and Parks; the Wisconsin Department of Natural Resources; the U.S. Geological Survey (USGS) Minnesota Cooperative Fish and Wildlife Research Unit; and the USGS Mississippi Cooperative Fish and Wildlife Research Unit. We are grateful to Shaun Killen and Cory Suski for improving earlier drafts of this manuscript. We thank FLW Outdoors for supplying fish transport bags and perforated weigh-in boxes,and we thank Ranger Boats for supplying the LWs. This research was conducted in compliance with animal use practices of the University of Minnesota (Protocol Number 0504A69169). Any use of trade,firm,or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The views and conclusions in this article represent the views solely of the authors from the USGS but do represent the views of the USGS.