Current fish husbandry practices generally produce cultured fish with reduced brain development and deviating behaviour compared to wild fish. This is particularly problematic for fish reared for compensatory restocking, which is characterized by high post-release mortality rates. From both an ethical and a financial point of view, we have an obligation to optimize survival of stocked fish through improving their neuronal and behavioural plasticity.
In this project, we will assess the feasibility of implementing exercise regimes as a novel method to improve fish cognition and foraging behaviour. Exercise has been shown to increase growth rates, improve feed conversion ratios and reduce stress in fish. In mammals, exercise can stimulate brain cell proliferation in the hippocampus and enhance cognitive performance (e.g. solving a maze quicker). Therefore, we predict that exercise can be an effective tool to improve fish cognition.
In this proposed collaboration with Wageningen University, the Netherlands, we will subject Atlantic salmon to an 8-week sustained exercise regime at either their optimal metabolic swimming speed or at a volitional speed. After the training regime, exercised and control (unexercised) fish will be subjected to a maze test to assess their cognitive capacity. Furthermore, fish will be provided a novel food source (live prey) to assess prey-handling skills. Brain plasticity and cell proliferation in the telencephalon will be visualized using histological techniques. Finally, growth parameters, feed conversion ratios and cortisol levels will be measured.
This study can have massive implications for restocking practices through identifying exercise as a practical and efficient tool to improve fish cognition. Furthermore, by assessing growth and stress parameters, the role of exercise as a tool to improve productivity and welfare of fish can contribute to more efficient and ethical aquaculture practices.