The role of uncertainty in the design of sustainable and precautionary management strategies for fisheries

Abstract

Environmental variability has a strong influence on marine fish stocks. Thus, management and harvest policies based on deterministic indicators, such as maximum sustainable yield (MSY), may be inappropriate facing such uncertainties. In this study, we investigate the long‐term behavior of a singlespecies fishery, whose stock is harvested by several fleets and affected by variability in the recruitment. The dynamics of this population is modeled by a discrete‐time stochastic age‐structured model. In this context, we introduce the concepts of maximum expected, log expected, and harmonic expected sustainable yield, as biological reference points. We illustrate these concepts with a case study of the Patagonian toothfish fishery in Chile and Argentina. Via Monte‐Carlo simulations, we verify that high levels of variability have a negative effect on all these maximum expected reference points, which suggests the need to be more cautious when large levels of variability on recruitment impact the fishery. Our simulations show that the deterministic MSY may not be attained in the presence of environmental noise, and therefore its use may lead to a failure of management strategies or rebuilding plans.