Applying economic guidelines to manage the Red Octopus (Octopus maya) fishery in the Yucatán Peninsula via harvest control rules

Abstract

We present a biomass-dynamic bioeconomic model that integrates economic aspects and guidelines for the management of the Red Octopus (Octopus maya) fishery, propose economic reference points, and incorporate economic considerations into harvest control rules (HCRs). This framework allows for the consequences of alternative management actions to be evaluated within a probabilistic context. To develop the biomass-dynamic bioeconomic model, we employed a framework based on  the Gordon-Schaefer model (Gordon 1954) without assuming equilibrium (constant stock size). Instead of fishing effort, the proposed model includes the annual cost per ton and is formulated in terms of biomass. We also established economic reference points, including a limit point based on bioeconomic equilibrium and a target point based on net profit at maximum sustainable yield (Π_MSY). These reference points were incorporated into the HCRs, along with management actions that are triggered when the fishery approaches each threshold. A Kobe plot indicated that overfishing occurred between 2009 and 2012 and confirmed that the O. maya stock was overfished in 2013. Accordingly, the HCRs recommend reducing fishing mortality. The model projections suggested that harvesting at 90% of the fishing mortality at maximum sustainable yield (F_MSY) would allow biomass to recover to that at maximum sustainable yield (B_MSY) in the medium term. The median of the posterior distribution of the bioeconomic model for net profit in 2018 was estimated at MX$428.8 million. The probability of the net profit being zero at a harvest rate of 0.9F_MSY was zero. Additionally, the probability that net profit was below Π_MSY in 2018 was 0.61.