The study of shark and ray abundance in Nusa Penida Aquatic Conservation Area

Limited information is one of major problem in managing shark and ray population in Indonesia. This research aims to demonstrate a cost-effective video approach to quantify the relative abundance of sharks, rays and other megafaunas (morays, turtles and sea snakes) in no-take and open access zones of Nusa Penida Aquatic Conservation Area. Using 116 deployments of baited remote underwater video systems (BRUVs) that deployed in March 2016, we found 162 individual sharks, rays and another megafauna. Three shark species from three families were identified: blacktip reef shark (Carcharhinus melanopterus, n=2), bigeye thresher shark (Alopias superciliosus, n=1) and bamboo shark (Chiloscyllium punctatum, n=10). Bamboo shark are known to have low valueto shark fisher. Five species of rays from 2 families were recorded: blue-spotted mask ray (Neotrygon kuhlii, n=12), mangrove whip ray (Himantura granulata, n=8), blue-spotted ribbon-tail ray (Taeniura lymma, n=4), blotched fantail ray (Taeniurops meyeni, n=2) and manta ray (Manta spp, n=6). We found that the zoning of the Aquatic Conservation Area had no effect on shark abundance. However, shark abundance was different between sites (East and West Nusa Penida). Numbers of lower order predators such as bamboo sharks, stingrays and morays were relatively high, potentially due to the absence of larger sharks. Rays had greater abundance at sites with low current and in deeper water, while morays, turtles and sea snakes varied across site and current intensity. Redefining zoning needed to improve benefits of spatial closure on conserving sharks, rays and another megafaunas population.