Conservation status of coral reef sharks caught on camera

Shark populations have declined considerably over the past century due to the global demand for shark products and high levels of bycatch. However, blind spots remain in our understanding of the population status of sharks in coastal environments, such as coral reefs, where the majority of threatened species occur. Here, Aaron MacNeil and colleagues examine the conservation status of coral reef sharks around the world, using data from over 15,000 baited remote underwater video stations dropped on 371 tropical coral reefs across 58 countries, states and territories. Sharks were not seen in 19% of reefs surveyed and 63% of the video stations did not record a single shark, indicative of widespread depletion of reef sharks across much of the tropics. Shark depletion was strongly related to socioeconomic conditions, such as the size and proximity of the nearest market, poor governance and high human population density. Shark sanctuaries, closed areas, catch limits, and an absence of gillnets and longlines were associated with 36–50% higher relative abundance on average. These findings point the way to policies to restore and manage reef shark populations.