A cautionary tale: management implications of critical transitions in oyster fisheries

Abstract

Given the global collapse of most oyster fisheries, we explored the conditions under which the interaction of oysters and fishers can lead to multiple system equilibria and how those conditions might affect management strategies and recovery efforts. Using simple, but plausible, models of oyster fisheries, we identified tipping points, multiple equilibria, and hysteresis under a wide range of realistic model parameterizations. In collapsed systems with hysteresis, recovery of the system will require far less harvest than that which precipitated the collapse, and recovery times can be on decadal scales. We also derived optimal, non-equilibrium, state-dependent fishing policies and found that these policies can perform well, but are accompanied by high variation in the allowable harvest. Critically, these optimal policies also require constant monitoring of system state and frequent control of fishing effort. Finally, we examined habitat-enhancement scenarios that mimic proposed and ongoing restoration programs. We found that these efforts can increase the number of fishers the system can support and reduce otherwise long recovery times in collapsed systems.