Evaluating Muskellunge (Esox masquinongy) Catch-and-Release Mortality at Elevated Summer Water Temperature

Abstract

Angling for Muskellunge (Esox masquinongy) has become widespread and increasingly popular throughout the fish’s range. Current management strategies for Muskellunge include high minimum harvest lengths (>1016mm), closed seasons, and catch-and-release regulations. Due to these strategies and angler sentiments, up to 97% of Muskellunge caught today are released by anglers assuming they will live and be caught again in the future. Previous research on catchand-release mortality in Muskellunge has suggested relatively low mortality rates (0%-5%). However, these studies were all conducted within the fish’s thermal optimum and generally at water temperatures25°C during the summer months, representing a need to evaluate mortality rates at these elevated temperatures. My objective was to quantify warm-water (>25°C) catch-and-release mortality rates in Muskellunge (>760mm) and identify factors influencing mortality using experimental ponds. Muskellunge (n=103) were stocked into eight earthen or plastic lined flow-through ponds (0.06-0.71 ha) at densities of/ha. Muskellunge (n=50) were angled utilizing specialized Muskellunge fishing gear at water temperatures between 19.57°C and 32.64°C. Thirty-two fish were caught at temperatures >25°C. Fish that remained uncaught during the experiment were used as controls (n=53). Fish were closely monitored for 2 weeks after being angled to assess mortality. Mortality was greater for angled (32.0%) compared to control fish (9.4%). Differences in catch-and-release mortality was compared across a range of temperature regimes using firth’s logistic regression. Five-day cumulative temperature and net time were found to have a significant positive correlation with mortality. No significant correlations between fight time, hooking location, size, or gender and mortality. Elevated catch-and-release mortality rates at warm-water temperatures warrant investigations into the population level effects that varying degrees of exploitation may have during these periods.