Dynamics and biological reference points in a stochastic age-structured fish population model with an illustration of the Patagonian toothfish population

Abstract: In this manuscript we investigate the long-term behavior of a single-species fishery, which is harvested by several fleets. The time evolution of this population is modeled by a discrete time stochastic age-structured model. We assume that incertitude only affects the recruitment. First, for the deterministic version of this model, we characterize the equilibrium yields in terms of the fishing mortality. Then, for the stochastic version, we introduce the concepts of maximum expected, log expected and harmonic expected sustainable yield, and we analyze how the incertitude affects the behavior of these yields and their stationary distribution. All the numerical simulations are performed with data obtained from Patagonian Tooth-fish fishery, which is harvested by four different type of fleets: Chilean Industrial fleet, Chilean Artisanal fleet, Argentinean longline fleet, and Argentinean Artisanal fleet.