Reef manta rays (Mobula alfredi) occur in small, isolated populations associated with island or coastal reef systems, and are susceptible to anthropogenic impacts. M. alfredi are often observed interacting in groups, and perform many apparently socially-mediated behaviours. Social structure has been shown to affect spatial ecology in other elasmobranchs, and may be an important link between the behaviour of individuals and population-based phenomena such as disease transmission, response to environmental change and susceptibility to fisheries.
In this study we provide quantitative evidence for structured social relationships in reef manta rays (Mobula alfredi). We show that the reef manta ray population in Raja Ampat may be partly segregated into communities displaying strong and fine-scale preferences for particular locations, with social network structure that is conserved over time. By controlling for non-social factors, we show that reef manta rays exhibit social preferences that are not simply the result of common attraction to particular habitats or resources.
Results suggest that effective conservation and management of M. alfredi should consider how variation in individual social behaviour and habitat use shapes population structure, and may be used to guide plans for minimal-impact dive tourism in key habitats.