title: Predatory fish depletion and recovery potential on Caribbean reefs.
abstract: The natural, prehuman abundance of most large predators is unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomass at a given location (that is, the predator carrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reef fish biomass and several anthropogenic and environmental variables at 39 reefs across the Caribbean to (i) estimate their roles determining local predator biomass and (ii) determine site-specific recovery potential if fishing was eliminated. We show that predatory reef fish biomass tends to be higher in marine reserves but is strongly negatively related to human activities, especially coastal development. However, human activities and natural factors, including reef complexity and prey abundance, explain more than 50% of the spatial variation in predator biomass. Comparing site-specific predator carrying capacities to field observations, we infer that current predatory reef fish biomass is 60 to 90% lower than the potential supportable biomass in most sites, even within most marine reserves. We also found that the scope for recovery varies among reefs by at least an order of magnitude. This suggests that we could underestimate unfished biomass at sites that provide ideal conditions for predators or greatly overestimate that of seemingly predator-depleted sites that may have never supported large predator populations because of suboptimal environmental conditions.
authors.affiliation: Center for Biological Diversity, 1212 Broadway Suite 800, Oakland, CA 94612, USA.
authors.forename: Abel
authors.initials: A
authors.lastname: Valdivia
authors.affiliation: National Museum of Natural History, 1000 Constitution Avenue Northwest, Washington, DC 20560, USA.
authors.forename: Courtney Ellen
authors.initials: CE
authors.lastname: Cox
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Wilson Hall, 120 South Road, Chapel Hill, NC 27599, USA.
authors.forename: John Francis
authors.initials: JF
authors.lastname: Bruno
mesh_terms: D000818:Animals; D018533:Biomass; D017691:Caribbean Region; D057894:Coral Reefs; D005398:Fisheries; D005399:Fishes; D006801:Humans
keywords: Coral reefs; carrying capacity; coastal development; fish biomass; habitat complexity; human population density; marine reserves; overfishing; predatory reef fish; trophic levels