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

Abstract

Differences in behavior and physiology amongst individuals often alter relative fitness levels in the environment. However, the ideal behavioral/physiological phenotype in a given environment may be altered by human activity, leading to an evolutionary response in the affected population. One example of this process can be found in fisheries (including recreational freshwater fisheries), where selective capture and harvest of individuals with certain phenotypes can drive evolutionary change. While some life history traits and behavioral tendencies influencing capture likelihood have been studied, the physiological mechanisms driving this vulnerability remain poorly understood. To address this, we assessed how two major physiological characteristics (hormonal responsiveness to stress and metabolic phenotype) and one behavioral characteristic (boldness) impact the likelihood of an individual being captured by anglers. Largemouth bass, Micropterus salmoides, derived from a population artificially selected for differential angling vulnerability were assessed for boldness and for stress responsiveness (as indicated by plasma cortisol levels) following an air-exposure challenge. Largemouth bass were then stocked into a pond where experimental angling trials took place, and a subset of captured and uncaptured fish were afterwards assessed for metabolic phenotype. The results showed that stress responsiveness was the primary driver of angling vulnerability, with individuals that experienced lower rises in cortisol following the air-exposure challenge more likely to be captured. Neither boldness nor metabolic phenotype influenced capture probability. The results from this study indicate that fisheriesinduced selective pressure may act on physiology, potentially altering stress responsiveness and its associated behaviors in populations exploited by recreational anglers.

A physiological perspective on fisheries‐induced evolution

“…For passive gears, it has been suggested that decision‐making after the initial gear encounter is a greater determinant of individual vulnerability to capture than encounter rate itself (Klefoth et al., ; Monk & Arlinghaus, ). In largemouth bass, individuals with low stress responsiveness are more vulnerable to capture by angling, although the exact stage of the capture process that is affected by endocrine traits was not identified (Louison, Adhikari, Stein, & Suski, ). Interestingly, however, boldness and metabolic traits did not influence capture vulnerability in this study, providing evidence that the decision to engage with the deployed gear after discovery was at least partially detached from foraging requirements, exploration or risk‐taking per se.…”

Largemouth bass use prior experience, but not information from experienced conspecifics, to avoid capture by anglers

“…To test these learning mechanisms more explicitly, an angling-naïve population of hatchery-raised largemouth bass Micropterus salmoides was used. In addition to being easy to hold in captivity, largemouth bass were used in this study because this species is among the most popular recreational angling targets in all of North America (Gaeta, Beardmore, Latzka, Provencher, & Carpenter, 2013) and has been extensively studied in the context of vulnerability to capture via recreational angling (Hessenauer et al, 2015;Louison, Adhikari, Stein, & Suski, 2017;Philipp et al, 2009). Upon completion, the results from this study will develop understanding of the role learning plays in angling vulnerability and which mechanisms are used by largemouth bass to avoid capture.…”

Behavioural adjustment of fish to temporal variation in fishing pressure affects catchability: an experiment with angled trout

“…Importantly, under low angling frequency, in addition to higher rates of recapture, we also observed an increase in the total number of captured fish, suggesting population-level decrease in threat perception and vigilance level rendering a larger pool of fish vulnerable to capture. Previous studies have shown that individual fish differ in their intrinsic vulnerability to capture and have identified several drivers related to individual differences in risk-taking behaviour and stress resilience (also termed coping styles; Louison et al 2017;Koeck et al 2018). In particular, it has been shown that individual differences in the activation of the hypothalamic-pituitary-interrenal axis (HPI axis) were related to individual differences in vulnerability to angling in rainbow trout (Koeck et al 2018).…”