Management of fluctuating fish stocks: the case of Pacific whiting

All commercially valuable fish stocks fluctuate annually and this leads to challenges for fishery management. The biomass of Pacific whiting (Meluccius productus) is subject to large fluctuations owing to the highly variable nature of recruitment. A stochastic population dynamics model which includes multiple fishery sectors and a hockey stick stock-recruitment relationship tailored to generate occasional extremely strong year-classes is developed. Simulation is then used to evaluate the performance of various harvest strategies in terms of average catch, variation in catch, the probability of closing the fishery, and a variety of other conservation-related performance measures. The simulations account for the error and imprecision associated with estimating biomass from stock assessments. Most of the harvest strategies are based on constant escapement. The “best performing” of the harvest strategies involves closing the fishery only when the biomass is estimated to be below 5% of its pre-fishery size and in which catches increased fairly slowing with increasing biomass.