Evidence from terrestrial systems and aquatic systems in captive conditions suggests that social behaviour is a critical component to understanding individual fitness and population resilience. In addition, behaviour at the spatial-social interface is subject to constant change due to environmental or human- related effects. The degree to which individuals vary in their responses to those changes and how social structure re-organizes after a perturbation remains largely unexplored, but can determine population resilience in face of climate change. In BELAS, we will investigate overlooked levels of behavioural variation at the spatial-social interface and explore how they can be used to boost the conservation of fish populations. We will do so using coastal elasmobranchs as a study case. Elasmobranchs are particularly relevant for this purpose because they are one of the most endangered groups of vertebrates on earth but display key roles to sustain healthy ecosystems. Besides, sharks and rays have rich social lives making them excellent model species to explore sociality in the wild. By tracking multiple individuals from several model species at multiple spatial and temporal scales, we expect to provide unprecedented information on the degree of individual variation in behaviour in natural populations of fish, and its relevance for the ecology of conservation at various levels, ranging from short-scale social interactions to long term movement strategies.