An analysis of harvest strategies and information needs in the purse seine fishery for the Brazilian sardine

Abstract

This paper evaluates a range of constant harvest rate, constant escapement, and effort control strategies in the purse seine fishery for the Brazilian sardine by accounting for uncertainties in the processes controlling recruitment and catchability. Control strategies are evaluated with a delay-difference simulation model representing three hypotheses about sardine stock–recruitment relationship, involving the effect of spawning stock size, depensation and cyclic environmental regimes. Strategies are compared by the predicted average catches, catch variability, and probability of stock collapse. Results from simulations are also used to evaluate the relative merits of different types of policies and to evaluate the relative values of reducing the uncertainties about sardine recruitment dynamics. Better understanding of the processes controlling recruitment is mostly needed if the fishery is to continue being managed by effort control. Constant harvest rate policies provide better trade-off among the performance indicators and appears more robust to uncertainties on the prevailing ecological processes controlling recruitment. Results from this analysis are used to discuss the type of research that would most likely provide the information needed to improve the quality of decisions in the purse seine fishery.