How farmed fish cope with stress

The COPEWELL (A new integrative framework for the study of fish welfare based on the concepts of allostasis, appraisal and coping styles) project explores the complex relationship between fish brain function, behaviour, physiology and adaptive plasticity. The target species are the three most important European cultured fish species: Atlantic salmon (Salmo salar), European sea bass (Dicentrarchus labrax) and the Gilthead sea bream (Sparus auratus).

The project aimed to increase knowledge on the basal mechanisms underpinning individual variability in coping ability and behaviour. Researchers have studied the ontogeny of the stress axis and identified key elements of the stress responses and changes induced in various parts of the fish brain, with a special focus on the telencephalon, hypothalamus and pituitary. By exposing fish to stressors of different nature, intensity and predictability, the scientists assessed the allostatic load – that is, the physiological sum of the 'wear and tear' on fish as a result of stress comparing individuals displaying alternate coping strategies. Also, tools were devised to understand how the fish respond to their environment based upon appraisal theory (e.g. choice of specific locations based on positive/negative stimuli expectancy). These studies provide an understanding of the subjective welfare experience as an evolved survival mechanism.

Expected impacts of COPEWELL include a deeper understanding of how fish appraise their world and cope with the environment, the development of the brain function, and a working framework of the behaviour and stress response in relation to the different husbandry practices and rearing methods of farmed fish. This will also help to understand how and when short or long episodes of stress during early life affect the welfare and quality of juveniles and adult fish.

Project results should have a significant impact on husbandry practices and rearing methods on fish farms. This should promote higher fish yields as well as increase fish welfare.