Differences in the Metabolic Rates of Exploited and Unexploited Fish Populations: A Signature of Recreational Fisheries Induced Evolution?

Abstract

Non-random mortality associated with commercial and recreational fisheries have the potential to cause evolutionary changes in fish populations. Inland recreational fisheries offer unique opportunities for the study of fisheries induced evolution due to the ability to replicate study systems, limited gene flow among populations, and the existence of unexploited reference populations. Experimental research has demonstrated that angling vulnerability is heritable in Largemouth Bass Micropterus salmoides, and is correlated with elevated resting metabolic rates (RMR) and higher fitness. However, whether such differences are present in wild populations is unclear. This study sought to quantify differences in RMR among replicated exploited and unexploited populations of Largemouth Bass. We collected age-0 Largemouth Bass from two Connecticut drinking water reservoirs unexploited by anglers for almost a century, and two exploited lakes, then transported and reared them in the same pond. Field RMR of individuals from each population was quantified using intermittent-flow respirometry. Individuals from unexploited reservoirs had a significantly higher mean RMR (6%) than individuals from exploited populations. These findings are consistent with expectations derived from artificial selection by angling on Largemouth Bass, suggesting that recreational angling may act as an evolutionary force influencing the metabolic rates of fishes in the wild. Reduced RMR as a result of fisheries induced evolution may have ecosystem level effects on energy demand, and be common in exploited recreational populations globally.

Hormonal responsiveness to stress is negatively associated with vulnerability to angling capture in fish

“…This finding was contrary to our initial predictions, which were based on a number of previous studies documenting that high metabolic rates may increase the likelihood of a fish being captured, albeit via different gear types (Biro and Post, 2008). Other work has also indicated that angling pressure may lead to a reduction in metabolic rate in exploited populations, likely as a result of the selective capture of individuals with higher metabolism (Hessenauer et al, 2015). Alterations to metabolic phenotype via the selective capture and removal of individuals with high metabolic rates could potentially have fitness-related outcomes for exploited populations, as metabolism is closely linked to growth rate and overall productivity as well as the likelihood of mortality (Biro and Stamps, 2008;Myles-Gonzalez et al, 2015).…”

Toward a mechanistic understanding of vulnerability to hook‐and‐line fishing: Boldness as the basic target of angling‐induced selection

“…Growth rate also likely integrated the independent effects of unmeasured physiological and behavioral traits. For example, links among behavior, learning ability (DePasquale, Wagner, Archard, Ferguson, & Braithwaite, ; Kotrschal et al., ; Trompf & Brown, ), and metabolic rate (Biro & Stamps, ) have been reported in other studies (Hessenauer, Vokoun, Davis, Jacobs, & O′Donnell, ; Hessenauer et al., ), which may all affect growth rate (Redpath, Cooke, Arlinghaus, Wahl, & Philipp, ; Redpath et al., ). In line with Biro and Sampson (), we thus tentatively conclude that a sizable fraction of the remaining “direct” selection on juvenile growth rate can be explained by variation in unmeasured energy‐acquisition‐related behaviors (Enberg et al., ), for example, individual variation in intensity of ingesting baited hooks and freely available baits (Gutmann Roberts, Bašić, Amat Trigo, & Britton, ).…”

Passive gear‐induced timidity syndrome in wild fish populations and its potential ecological and managerial implications

“…; Hessenhauer et al . ). Depending on the local availability of food, less vulnerable individuals with lower metabolic rates may actually grow faster, and not slower, than their high‐vulnerable, high metabolic rate, more aggressive conspecifics who under food limitation might not be able to turn their genetically higher growth capacity into rapid somatic growth (as shown in largemouth bass selected for vulnerability to angling, Micropterus salmoides , Centrachidae, Redpath et al .…”

“…) and indirectly through correlated changes in population‐level metabolic rates (Hessenhauer et al . ). However, the predictions of what effects to expect are not clear cut.…”