An endogenous bioeconomic optimization algorithm to evaluate recovery plans: An application to southern hake

Abstract

Recovery plans were analysed by introducing social and economic behaviour and endogenous disinvestment decisions into bioeconomic models. Considering these endogenous constraints, a dynamic optimization problem was solved to find fishing mortality (F) trajectories that maximize discounted profits per vessel, subject to recovery of the stock to a spawning-stock biomass (SSB) target in 2015. The algorithm developed was used to assess the southern hake recovery plan. Three scenarios were analysed: (1) represents the current plan with an annual 10 reduction in F; (2) represents the optimum trajectory where profits must be positive all along and the SSB target is reached no later than 2015, and (3) represents the optimum trajectory allowing profits to be negative. The results from (3) indicate that if economic and social restrictions are not considered a prior condition, the optimum solution implies a fleet reduction in 2010 and 2011. Comparing (1) and (2), our results suggest that reducing F to 0.30 by 2010 achieves the recovery target in 2012, increases the net present profits by 7.7 relative to the current plan, and is compatible with maintaining the current fleet size. © 2010 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.