Demonstration Management Strategy Evaluation for Chub Mackerel Using Open-Source Tools

The purpose of this paper was to provide a complete technical MSE exercise to demonstrate MSE accessibility in the light of new open-source software. A single structural form of MP was developed that sets TACs to a fixed multiple of observed relative abundance indices. Twelve derivatives of this MP were tested that included varying index multipliers and numbers of years for smoothing the observed index. These MPs were tested over a two-dimensional grid of operating models including three scenarios for natural mortality rate and two for index hyperstability. These operating models were conditioned using existing VPA assessment tools for chub mackerel. When tested by MSE closed-loop simulation, the performance of the MPs spanned a wide trade-off between biomass and yield outcomes. In general performance was encouraging but a wider range of operating models that include future recruitment scenarios would provide a substantially tougher test of such MPs. Priorities for development of an MSE framework include the specification of management performance metrics and the identification of core uncertainties in system dynamics for the conditioning of operating models.