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Plasticity of coping styles in farmed fish: behavioural and neuro-endocrine profiling

Publication . Castanheira, Maria Filipa Bento de Oliveira Falcão; Conceição, Luís E.C.; Martins, Catarina I. M.; Kristiansen, Tore

Intensive aquaculture practices frequently expose fish to a range of stressors. Gilthead seabream (Sparus aurata) is the most important farmed species in the Mediterranean, and like in other vertebrates, exhibit pronounced individual differences in stress responsiveness, however to which extent such variability is part of coping styles remains unclear. As such, this Thesis aimed to provide methods and tools to analyse coping styles in seabream, with specific reference to the presence, variability and consistency of individual trait correlations relevant to fish welfare. Using an evolutionary approach, it integrated and explored the adaptive links between behaviour, physiology and brain function, especially aiming to explore individual variation in adaptive responses of seabream when exposed to the same stressful situation. The background and consequences of coping styles in aquaculture is introduced in Chapter 2. Chapter 3 aims to quantify individual differences in cortisol response in seabream and to assess whether it can predict aggressive behaviour. Results provided the first evidence for a link between HPI responsiveness and aggressive behaviour in seabream. This suggests that individual differences in aggression are part of coping styles and therefore can be predictive of and predicted from other traits. In Chapter 4, it was investigated, for the first time in seabream, whether individual differences in behavioural responses to a variety of challenges are consistent over time and across contexts using both individual and grouped-based tests. Results suggest consistency over time and across-context in behavioural responses to challenges both using individual and grouped-based tests. This study highlights the possibility to predict behaviour in groups from individual coping traits. One of the traits that has been shown to be consistent over time and across context in the Chapter 4 was the escape response under a restraining test. Using this trait as a proxy of coping styles in seabream the consistency of escape behaviour was investigated in Chapter 5 and 6. In Chapter 5 we investigated the effect of avoidance in gilthead seabream kept under different social contexts, i.e. the influence of other group members on individual avoidance behaviour consistency. The results demonstrate that grouping individuals with similar coping styles induces changes in coping styles whereas grouping individuals with different coping styles favours coping styles to remain the same. These findings suggest an influence of the social environment in seabream coping styles. In Chapter 6 we investigate the long term consistency of coping styles both, over time and during different life history stages. Our results show consistent behaviour traits in seabream when juveniles, and a loss of these behavioural traits when adults. Therefore, these results underline that adding a life history approach to data interpretation is as an essential step forward towards understanding coping styles. Chapter 7 aimed to characterize the stress coping ability and brain function in seabream, by investigating the behavioural and forebrain physiological responses of fish displaying contrasting coping styles to the same stimulus (escape response under a restraining test). Results show differences in activation of region-specific telencephalic regions between seabream displaying contrasting coping styles. It confirms the hypothesis that in seabream, inhibitory and excitatory markers of neural function appear to be associated with reactive and proactive coping styles, respectively. The main findings of this thesis are discussed and the main conclusions are presented in Chapter 8. It is concluded that fish with contrasting stress coping styles show clear differences in behavioural and physiological parameters. Moreover, these differences can change according to social environment and life history. In general this Thesis has generated new knowledge of the mechanisms underlying individual responses of fish to stress providing new insights on the interrelations between different relevant husbandry practices, fish performance and welfare.

2016-07-22Doctoral thesis

Open Access

Are coping styles consistent in the teleost fish Sparus aurata through sexual maturation and sex reversal?

Publication . Castanheira, Maria Filipa; Martinez Paramo, S.; Figueiredo, F.; Cerqueira, Marco; Millot, Sandie; Oliveira, Catarina C. V.; Martins, Catarina I. M.; Conceicao, Luis E. C.

Individual differences in behaviour and physiological responses to stress are associated with evolutionary adaptive variation and thus raw material for evolution. In farmed animals, the interest in consistent trait associations, i.e. coping styles, has increased dramatically over the last years. However, one of limitations of the available knowledge, regarding the temporal consistency, is that it refers always to short-term consistency (usually few weeks). The present study used an escape response during a net restraining test, previously shown to be an indicative of coping styles in seabream, to investigate long-term consistency of coping styles both over time and during different life history stages. Results showed both short-term (14 days) consistency and long-term (8 months) consistency of escape response. However, we did not found consistency in the same behaviour after sexual maturation when the restraining test was repeated 16, 22 and 23 months after the first test was performed. In conclusion, this study showed consistent behaviour traits in seabream when juveniles, and a loss of this behavioural traits when adults. Therefore, these results underline that adding a life story approach to data interpretation as an essential step forward towards coping styles foreground. Furthermore, a fine-tuning of aquaculture rearing strategies to adapt to different coping strategies may need to be adjusted differently at early stages of development and adults to improve the welfare of farmed fish.

2016-10Journal article

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Are personality traits consistent in fish? The influence of social context

Publication . Castanheira, Maria Filipa; Cerqueira, Marco; Millot, Sandie; Gonçalves, Rui A.; Oliveira, Catarina C. V.; Conceição, Luis E. C.; Martins, Catarina I. M.

Individual differences in behavioural and physiological responses to challenges are progressively accepted as adaptive variation and reveal a strong degree of evolutionary conservation throughout the vertebrate taxa. Previous studies in gilthead seabream (Sparus aurata) suggested that individual differences in behaviour reflect distinct coping styles or personality, contrasting consistent traits associations. One of the traits that have been shown to be consistent over time and across context is the escape response under a restraining test. Using this trait as a proxy of personality in seabream the influence of social context in the consistency of escape behaviour was investigated. Individually tagged juvenile seabream (n = 360; 70.18 +/- 11.44 g; mean +/- SD) were subjected to a restraining test that consisted of keeping each fish in an emerged net for one minute. Behaviours measured in the net (latency to escape; number of escape attempts and total time spent on escaping) were collapsed into first principal component scores using Principal Components Analysis (PCA). Using the PCA scores the individuals were distributed into homogeneous groups (n = 30 each group) of proactive, reactive and intermediate. Control groups consisted of mixed groups with 1/3 of each coping style. After one month the same individuals were exposed to the same test (restraining test) to assess consistency of behavioural responses. Results indicate that homogenous groups of proactive (p = 0.086) and reactive (p = 0.159) individuals did not exhibit consistent behavioural responses as opposed to the intermediate (p = 0.028) and control groups (p < 0.001). This study thus confirms that the social context in which fish are kept significantly influence personality traits. (C) 2016 Elsevier B.V. All rights reserved.

2016-05Journal article

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