Predatory fish depletion and recovery potential on Caribbean reefs

The natural, prehuman abundance of most large predatorsis unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomassat a given location (that is, the predatorcarrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reeffish biomassand several anthropogenic and environmental variables at 39 reefsacross the Caribbean to (i) estimate their roles determining local predator biomassand (ii) determine site-specific recovery potential if fishing was eliminated. We show that predatory reeffish biomasstends to be higher in marine reservesbut is strongly negatively related to human activities, especially coastal development. However, human activities and natural factors, including reefcomplexity and prey abundance, explain more than 50% of the spatial variation in predator biomass. Comparing site-specific predatorcarrying capacities to field observations, we infer that current predatory reeffish biomassis 60 to 90% lower than the potential supportable biomassin most sites, even within most marine reserves. We also found that the scope for recovery varies among reefsby at least an order of magnitude. This suggests that we could underestimate unfished biomassat sites that provide ideal conditions for predatorsor greatly overestimate that of seemingly predator-depleted sites that may have never supported large predatorpopulations because of suboptimal environmental conditions.