Predation, competition, and the recovery of overexploited fish stocks in marine reserves

Community interactions alter the management actions necessary to recover overfished species using marine reserves. For example, in communities where a larger species preys on their juveniles' competitors, overfishing of the larger species may cause prey population expansion; subsequent increased competition for the juveniles of the over fished species may impede its recovery within reserves. We explore the implications of such community interactions for reserve design with a model of a subtidal rockfish (genus Sebastes) system from the Northeast Pacific Ocean within a no-take reserve. Ignoring community interactions, the model predicts that a reserve large enough for internal recruitment to counterbalance mortality will allow recovery of the overfished species. However, after incorporating community interactions, the model predicts that two alternative stable states exist: one where the overfished species dominates and one where the prey dominates. In the community model, the ability of an overfished system to recover to the equilibrium where the overfished species dominates after reserve establishment depends on the initial densities of both species, and a larger reserve is required for recovery to be possible.