1. Reef sharks are declining worldwide under ever increasing fishing pressure with potential consequences on ecosystem functioning. Marine protected areas (MPAs) are currently one of the management tools to counteract the pervasive impacts of fishing. However, MPAs in which reef sharks are abundant tend to be located in remote and underexploited areas preventing a fair assessment of management effectiveness beyond remoteness from human activities. 2. Here we determine the conditions under which MPAs can effectively protect sharks along a wide gradient of reef accessibility, from the vicinity of a regional capital towards remote areas, using 385 records from Baited Remote Underwater Video Systems (BRUVS) and 2790 Underwater Visual Censuses (UVC) performed in areas open to fishing and inside 15 MPAs across New Caledonia (south-western Pacific). 3. We show that even one of the world’s oldest (43 years), large (172 km²) and most restrictive (no-entry) MPA (Merlet reserve) on coral reefs has between 17.3 % and 45.3% fewer shark species and between 37.2 % and 79.8 % fewer shark abundance than remote areas in a context where sharks are not historically exploited. 4. On coral reefs situated at less than 1 hour of travel time from humans, shark populations are so low in abundance (less than 0.05 individuals per 1000 m²) that their functional roles is severely limited. 5. Synthesis and applications. Remote areas are the last sanctuaries for reef sharks and provide a new baseline to evaluate human impacts with no equivalent close to human activities even in large, old and strongly restrictive MPAs. As such they deserve strong protection efforts. The large and no-entry MPAs close to humans offer limited benefits for reef shark populations but provide more realistic conservation targets for managers of human-dominated reefs. The exclusion of human activities on a sufficiently large area is key to protect reef shark populations. However, this strategy remains difficult to apply in many countries critically depending on reef resources for food security or livelihood.14-Aug-2017

Data_Juhel_JAE_2017Shark abundance and richness in New Caledonia using Baited Remote Underwater Systems (BRUVS) and Underwater Visual Censuses (UVC)