Inter-Individual Differences in Stress Responsiveness Drive Vulnerability to Angling in Largemouth Bass

Recreational freshwater fisheries face numerous challenges, among them the evolutionary alteration of populations via selective capture of individuals with particular characteristics by anglers.  This selection may act not only on life history traits, but also the behaviors and physiological traits that predispose individuals to striking a fishing lure and being captured.  We tested whether levels of boldness, cortisol responsiveness to a stress challenge, and/or metabolic characteristics would predispose individual fish to capture (and thus be potentially under selective pressure in exploited populations) utilizing a specialized population of largemouth bass Micropterus salmoides artificially selected for differing intrinsic vulnerability to capture.  The results showed a significant role for cortisol responsiveness in the determination of angling vulnerability; specifically that lower responding individuals (i.e. proactive stress copers) were more likely to be captured.  Individual cortisol responsiveness however was not correlated with levels of boldness, and boldness itself was generally unrelated to capture probability.  No differences in any measures of metabolic rate were found between captured and uncaptured individuals.  The findings of this study indicate that fisheries-induced selective pressure may act on physiology, potentially altering these characteristics and their associated behaviors in exploited populations.