Diversity and abundance of sharks in no-take and fished sites in the marine protected area network of Raja Ampat, West Papua, Indonesia, using baited remote underwater video (BRUVs)

Abstract

Sharks are essential elements for healthy marine ecosystems and require conservation. A new law has been passed for their protection in Raja Ampat, Indonesia, yet there is a lack of knowledge about their current status in the region. This research quantifies diversity and abundance of shark populations in two areas (Penemu and Dampier Straight) within Raja Ampat, and provides a comprehensive baseline for the areas to evaluate management strategies. Baited remote underwater video systems were used to survey shark populations in no-take and fished sites, across a 3 to 80 m depth gradient. Overall, nine species of sharks from five families were recorded; Carcharhinus melanopterus was the most abundant species. PERMANOVA analysis showed no statistical difference between areas nor zoning status; likely due to the relatively recent designation of the Marine Protected Areas (MPAs) and inconsistent management/enforcement. Greater shark abundance overall was recorded in Penemu than in Dampier Strait, whereas Dampier exhibited greater diversity of species. Penemu also showed a greater difference in shark abundance between the fished and no-take zones, with more sharks in fishing-prohibited no-take zones. Over the depth gradient studied, there was an inverse trend for species richness and abundance, with the greatest shark abundance in shallow samples, whereas the greatest shark diversity was at depth. These results provide important knowledge on the distribution of these valuable, yet poorly understood, apex predators in Raja Ampat, West Papua. Furthermore the findings and protocols developed in this study will benefit the management planning of the Raja Ampat MPA network.