Walleye Mortality during Live-Release Tournaments on Lake Oahe, South Dakota

Abstract

Abstract Mortality of walleyes Stizostedion vitreum was estimated during two live-release tournaments held in May 1990 and May 1991 on Lake Oahe, South Dakota. Mortality was divided into three components: weigh-in, delayed, and total. Weigh-in mortality was the percentage of walleyes that could not be released alive. Delayed mortality was calculated from walleyes that died in submersed cages after 3 d. Total mortality was determined by adding weigh-in deaths and delayed deaths, after applying the delayed mortality to all released fish. Weigh-in mortality averaged 18.4% in 1990 and 13.2% in 1991. Delayed mortality was estimated to be 5.5% for 1990 and 8.4% in 1991. Total mortality was 22.8% in 1990 and 20.5% in 1991. These rates were similar to results under similar conditions reported by other researchers. Released walleyes were tagged to monitor their later contribution to the creel. Returns of tags from tournament-released walleyes averaged 29.5% compared with 12.4% for walleyes tagged during annual spa...