Using data from what was once one of the world’s largest capture fisheries the economic value of a marine reserve is calculated using a stochastic optimal control model with a jumpdiffusion process. The results show that with a stochastic environment an optimal-sized marine reserve can generate a triple payoff that (a), raises the resource rent even when harvesting is ‘optimal’, (b) decreases the recovery time for the biomass to return to its former state and smooths fishers’ harvests and resource rents, and (c), lowers the chance of a catastrophic collapse following a negative shock.