ORIGINAL ARTICLE: Life‐history traits and energetic status in relation to vulnerability to angling in an experimentally selected teleost fish

Abstract

In recreational fisheries, a correlation has been established between fishing-induced selection pressures and the metabolic traits of individual fish. This study used a population of largemouth bass (Micropterus salmoides) with lines of low vulnerability fish (LVF) and high vulnerability fish (HVF) that were previously established through artificial truncation selection experiments. The main objective was to evaluate if differential vulnerability to angling was correlated with growth, energetics and nutritional condition during the sub-adult stage. Absolute growth rate was found to be between 9% and 17% higher for LVF compared with HVF over a 6-month period in three experimental ponds. The gonadosomatic index in females was lower for LVF compared with HVF in one experimental pond. No significant differences in energy stores (measured using body constituent analysis) were observed between LVF and HVF. In addition, both groups were consuming the same prey items as evidenced by stomach content analysis. The inherent reasons behind differential vulnerability to angling are complex, and selection for these opposing phenotypes appears to select for differing growth rates, although the driving factors remain unclear. These traits are important from a life-history perspective, and alterations to their frequency as a result of fishing-induced selection could alter fish population structure. These findings further emphasize the need to incorporate evolutionary principles into fisheries management activities.

Recreational fishing selectively captures individuals with the highest fitness potential

“…Comparison of total lengths of offspring also revealed that HV offspring (51 mm, SD ± 6.2) were, on average, 5% smaller than LV offspring (54 mm, SD ± 5.4) in fall (Table 1), consistent with earlier findings for juvenile HV and LV largemouth bass raised under food-limited pond conditions (20). It is likely that the higher metabolic rates of HV offspring were responsible for their smaller sizes in the present experiment.…”

“…1B), as evidenced by the significant interaction between selection line and the covariate male size ( Table 1). The shorter duration of parental care seen for the smaller males may reflect their expected lower energy reserves coming out of winter, thereby limiting their ability to sustain parental care activities, a situation that may be particularly acute for smaller HV males because of their higher metabolic rates (19)(20)(21). The lower willingness for smaller HV males, as well as smaller and larger LV males, to provide parental care may also be due in part to their lower mating success (i.e., fewer eggs received) after spawning (23).…”

“…In some fisheries, such as recreational angling, selection seems to operate on angling vulnerability as a complex, heritable trait composed of a range of covarying physiological, behavioral, and life history traits (17,18), rather than body size per se. In the popular recreational fish species largemouth bass (Micropterus salmoides), for example, it has been shown that fish with higher vulnerability to angling also exhibit higher metabolic rates and more intensive parental care (19)(20)(21). Likely as a result of greater energetic expenditure, however, the largemouth bass that were genetically predisposed to being vulnerable to capture did not grow better under experimental pond conditions in which food was limited (20,21).…”

“…In the popular recreational fish species largemouth bass (Micropterus salmoides), for example, it has been shown that fish with higher vulnerability to angling also exhibit higher metabolic rates and more intensive parental care (19)(20)(21). Likely as a result of greater energetic expenditure, however, the largemouth bass that were genetically predisposed to being vulnerable to capture did not grow better under experimental pond conditions in which food was limited (20,21). Because more-vulnerable individuals may have particular behavioral phenotypes during mate choice that are desired by females (e.g., higher levels of aggression that presumably indicate a willingness to provide more intense parental care), they may still be reproductively more fit than their less-vulnerable conspecifics, despite their smaller body size.…”

Biochemical evolution in response to intensive harvesting in algae: Evolution of quality and quantity

“…Examples of biochemical evolution in response to indirect selection imposed by harvesting are rarer, however, and the results of the few such studies are mixed. For example, Redpath, Cooke, Arlinghaus, Wahl, and Philipp (2009) found no difference in lipid, protein or carbohydrate content between largemouth bass selected for different levels of vulnerability, despite marked changes in growth rates. In contrast, Moreno et al.…”