Boosting brains: exercise enhances cognition and neurone density in a fish reared for release into nature

Strategic release of hatchery-reared fish is critical for restoring marine fisheries resources. However, maintaining essential life skills in these cultured fish has been a century-old challenge in fisheries science, as growth and survival in the wild are often notably afflicted by the lack of natural stimuli in their rearing environments. Exercise training in fish hatcheries shows promise for enhancing physical and cognitive development and improving both neurological function and behavioural adaptations. Here, we assess the impacts of exercise at four water velocities (0, 1, 2 or 4 body lengths per s, [BL/s]) on cognition, brain and behaviour of black seabream, Acanthopagrus schlegelii. Results indicate exercise can improve cognition, evidenced by fewer navigation mistakes in a detour task. Exercise also positively influenced neurone density in the telencephalon, but it did not have the same effect in the cerebellum. Behavioural characteristics were mostly unaffected, but a tendency for higher activity levels was noted in fish exercised at 2 BL/s. These findings suggest that exercise at 2-4 BL/s benefits the cognitive performance of hatchery-reared fish destined for release into natural environments. Given the simplicity of incorporating exercise in hatchery environments, it offers a promising strategy to enhance fish performance postrelease in stock enhancement programmes. (c) 2025 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.