Ecosystem Thresholds and Reference Points for Adaptive Management of Coral Reef Fisheries

The sustainability of coral reef fisheries is poorly understood – including, the amount of fish biomass that can be removed from coral reefs without reducing sustainable fishery yield or altering the state of the system.  Using the empirical relationships between metrics of coral reef state and fish biomass, we develop reference points that inform ecosystem-based fisheries management. Several metrics (e.g., macroalgal cover, change in fish assemblage) show thresholds -- abrupt non-linear changes -- at high fish biomass levels supporting the concept that coral-dominated states are associated with high fish biomass coral-dominated states.  Other metrics show thresholds at lower fish biomass levels, suggesting that such levels may be associated with transitional states and finally macroalgae-dominated states.  We suggest that in data-limited coral reef fisheries, the ratio of fish biomass for each threshold of coral reef state to unfished fish biomass can be used to assess the risk of ecosystem state and develop reference points that guide precautionary management. The consistency of findings between Indian Ocean and Caribbean suggests that these spatially-derived reference points may be widely applicable to coral reef management and serve as quantitative management objectives, to which management can be held accountable.