Healthy fisheries support industrial economies, maintain resilient food webs, and offer countless services to society. The diversity of benefits translates into many disparate objectives for modern fisheries management to reconcile. Coral-reefs are introduced as a model system where objectives for maximizing fishing yields and maintaining calcifying ecosystem states that provide ecosystem services differ. These differences were quantified using an existing allometric food-web model that was calibrated to a ‘pristine’ system and tested for accuracy against field data from the tropical Pacific. We used this framework to reveal ecosystem consequences of three common fishing scenarios: 1) fishing only higher-value mesopredators by removing the oldest and largest individuals and taking a conservative approach to maximize cohort biomass production, 2) fishing through the mesopredator guild to focus on large, desirable herbivore species, and 3) simultaneously fishing both predator and herbivore guilds.
Results/Conclusions
The results revealed that both the standing stock and variability of algal accumulation were key attributes of ecosystem states that were most sensitive to fishing and best linked with modelled resilience and reactivity thresholds. Managing for desirable levels of resilience and reactivity to support corals and calcifying reef growth required balanced fishing across trophic guilds. Balanced fishing was challenging because predators had sustainable yields less than one magnitude of order lower than herbivores. However, sustainable predator populations reduced apparent competition between small and large herbivores, and increased target species production by up to 50%. In contrast, managing for maximum food-web biomass production for all species combined increased fishing profits, but profits were offset by losses of services provided to society that were forecasted to have disproportionally higher economic values (i.e., tourism, recreation, and shoreline protection). Ecosystem-based management targets were contrasted with modern fisheries policies to highlight focal areas for refining policies.