Marine predators such as sharks, tuna and billfish play unique and irreplaceable ecological roles. These roles include controlling trophic cascades, removing weak or diseased individuals, and translocating nutrients between habitats. Many populations of predators have experienced substantial declines since the 1950s, primary due to fishing, yet their distribution and abundance across diverse bathymetry and in relations to human density centres remain poorly understood. Protecting refuges – population hotspots that persist in the face of extraction and other pressures – is therefore a key component of successful conservation and marine protected area implementation. Addressing this severe gap in knowledge, the PhD candidate will determine the driving characteristic of marine predator refuges. The PhD candidate will be responsible for a mid-water (pelagic) baited remote underwater video systems (BRUVS) sampling programme targeting remote locations (Cape Verde, BIOT/Chagos, Galapagos, Caribbean, French Polynesia, New Caledonia), which still harbour rich predators populations, and which therefore may act as refuges. In addition, the candidate should expect to work with local NGO partners in order to assess the potential impact of existing spatial management regimes on pelagic species at the regional level. The ideal candidate will have experience with remote team-based field-work, and should have an strong interest in video-based sampling methodologies. Through a quantitative modelling framework the candidate will generate science with direct implication for conservation prioritisation. Particularly, the project will investigate predator sensitivity to future scenarios of human population growth and management strategies, thereby generating science directly applicable to policymakers and stakeholders.