Assessing Size-Dependent Population-Level Effects of Largemouth Bass Tournament Mortality

Abstract As black bass Micropterus spp. tournaments continue to grow in popularity, so too must evaluations on the population-level effects of live-release angling events. Although factors influencing the tournament mortality of individuals are well studied, assessments at the population level are lacking. We evaluated differences in tournament capture probability and survival of two size-classes of Largemouth Bass M. salmoides (medium: 381–457 mm; large: >457 mm) using a multistate mark–recapture model. Changes in estimated capture and survival rates of medium and large bass were then simulated to assess potential effects on population size structure. Tournament capture probabilities for medium bass were approximately three times higher than those for large bass, and tournament capture probabilities for both size-classes increased with air temperature. Medium bass also experienced higher survival rates than large bass after tournaments, and survival rates of both groups declined with increasing water temperature. Our simulations indicated that both increases in tournament capture probability and reductions in posttournament survival of large bass resulted in some reductions in population size structure. However, increases in tournament capture probability or reductions in tournament survival of medium bass or medium and large bass alone had little to no effect. Our results suggest that under the observed tournament conditions, tournaments have little effect on bass population size structure, but size structure could be reduced with higher capture probabilities and lower posttournament survival; this information is useful for managing the fishery effects of tournament angling. Our modeling approach also provides a framework for understanding population-level effects of tournaments on other populations under alternative conditions.