Exploiting animal personality to reduce chronic stress in captive fish populations

Abstract

Chronic stress is a major source of welfare problems in many captive populations, including fishes. While we have long known that chronic stress effects arise from maladaptive expression of acute stress response pathways, predicting where and when problems will arise is difficult. Here we highlight how insights from animal personality research could be useful in this regard. Since behavior is the first line of organismal defense when challenged by a stressor, assays of shy-bold type personality variation can provide information about individual stress response that is expected to predict susceptibility to chronic stress. Moreover, recent demonstrations that among-individual differences in stress-related physiology and behaviors are underpinned by genetic factors means that selection on behavioral biomarkers could offer a route to genetic improvement of welfare outcomes in captive fish stocks. Here we review the evidence in support of this proposition, identify remaining empirical gaps in our understanding, and set out appropriate criteria to guide development of biomarkers. The article is largely prospective: fundamental research into fish personality shows how behavioral biomarkers could be used to achieve welfare gains in captive fish populations. However, translating potential to actual gains will require an interdisciplinary approach that integrates the expertise and viewpoints of researchers working across animal behavior, genetics, and welfare science.

Trait sensitivity to stress and cognitive bias processes in fish: A brief overview

“…Fish personality traits, akin to those in humans, are conceptualized as latent axes of variation that underlie observed behaviors, and these traits are often quantified using mathematical models (for a detailed explanation, see Conrad et al, 2011 ; Prentice et al, 2022 ; Toms et al, 2010 ). Specific assays, such as the open-field test, the novel tank test, the emergence test, and the Y-maze, among others (e.g., Buenhombre et al, 2021 ), are employed to position fish along a continuous dimension defined by two or more axes of interest, such as boldness versus shyness.…”

“…This approach involves using correlational and multivariate analyses to establish behavioral clusters representing the underlying behavioral axes. For example, if a fish population exhibits variation in aggressiveness, it implies that certain individuals tend to be more aggressive, leading them to display behaviors such as attacking a mirror stimulus, engaging in increased rivalry displays, or frequently chasing tank mates (Prentice et al, 2022 ). However, recent findings indicate that there are distinct hormonal and genomic responses in fish when they engage in combat with real conspecific opponents compared to when they confront their own mirror images (Balzarini et al, 2014 ; Oliveira et al, 2016 ; Teles & Oliveira, 2016 ).…”

Among‐individual behavioural variation in the ornamental red cherry shrimp, Neocaridina heteropoda

“…Although evolutionarily motivated studies dominate the literature on animal personality (Briffa & Weiss, 2010), this phenomenon is increasingly recognised as having wider implications and applications. For example, Prentice et al (2022) argues how the integration of personality traits with stress physiology means artificial selection on behavioural biomarkers could be used to improve welfare in fish aquaculture (see also e.g. Castanheira et al, 2013;Ibarra-Zatarain et al, 2016).…”

“…In comparison, personality variation in invertebrates generally, and aquatic invertebrates in particular, has been less well studied (Gherardi et al., 2012 ). This omission matters because understanding personality variation is not only central to fundamental research on animal behaviour, but also increasingly relevant across more applied fields such as welfare (Prentice et al., 2022 ), ecotoxicology (Bertram et al., 2022 ; Ford et al., 2021 ) and invasion biology (Juette et al., 2014 ).…”

“…For example, Prentice et al. ( 2022 ) argues how the integration of personality traits with stress physiology means artificial selection on behavioural biomarkers could be used to improve welfare in fish aquaculture (see also e.g. Castanheira et al., 2013 ; Ibarra‐Zatarain et al., 2016 ).…”