Development of a stochastic bioeconomic model for the red octopus fishery on the Yucatan Peninsula: Implications for management

Although much effort has been dedicated to the management of the red octopus fishery on the Yucatan Peninsula (Mexico), managers have yet to incorporate economic aspects to ensure sustainable and profitable exploitation of this fishery resource. We developed a bioeconomic model that incorporated the uncertainty for the r and K parameters. We fit 3 models (Schaefer, Fox, and Pella–Tomlinson) to abundance index survey data and used the Akaike information criterion for model selection. The best fit corresponded to the Schaefer model. We built deterministic and stochastic versions of the Gordon–Schaefer model. Economic data (costs and prices) were determined from inter[1]views with fishermen. To estimate the posterior distributions of parameters and indicators, we used Bayesian methods with Markov chain Monte Carlo (MCMC) simulations. The deterministic results suggested that the maximum sustainable income was Mex$851.70 million, with a fishing effort of 3,650 fishing boats, while the maximum sustainable profit was $390.8 million, with a fishing effort of 2,472 fishing boats. The equilibrium point corresponded to an effort of 4,945 fishing boats. Regarding the stochastic model, the MCMC simulation results suggest that the maximum sustainable income distribution was not normal; its average was $856.1 million (SE 1.8) and the most likely value was $849.50 million. The most likely fishing effort at equilibrium was 4,970 fishing boats. Our results suggest the fishery could be operating close to the economic equilibrium point; if this is the case, fishing effort must decrease in order for annual profit to increase. Our approach will help make periodical re-evaluations of the fishery and establish management strategies to ensure the profitable and sustainable exploitation of the red octopus on the Yucatan Peninsula.

Bioeconomic analysis of skipjack tuna fisheries in North Gorontalo Regency, Indonesia

The model of the skipjack tuna resource management that can provide maximum rent can be done with a clear ownership regime (sole owner) or in the condition of MEY balance. However, the management and utilization of skipjack tuna resources must also consider the factors that can result in overfishing of both biological and economics overfishing. This study aims to assess the management and utilization of skipjack tuna fisheries resources in North Gorontalo Regency using a bioeconomic approach. Data processing is done by approaching the bioeconomic model using skipjack tuna fisheries biological and economic parameters. The results showed that the maximum rent obtained in skipjack fisheries in North Gorontalo Regency was at the MEY regime compared to the MSY and OA regime. However, based on the actual data obtained, it is known that the average production of skipjack tuna in North Gorontalo Regency has not reached the optimum catch value in the equilibrium condition of MSY (hMSY ), but in some period the actual catch value has passed the optimal catch value (hMSY ), this means that skipjack tuna has overfished (biological overfishing). While the actual production value of skipjack tuna catches in North Gorontalo Regency has passed the production of optimum MEY (hMEY ). This condition indicates that actually skipjack tuna resources have experienced an economic overfishing.

The Tide Effects on Bioeconomic Model of Sardina pilchardus, Engraulis encrasicolus and Xiphias gladius in Atlantic Moroccan Zone

The main objective of this work is the study of the effects of high tides and low tides on fishing effort, catches as well as profits in a bioeconomic model of populations of Sardina pilchardus, Engraulis encrasicolus and Xiphias gladius in Moroccan areas. To achieve this objective, we studied the stability of the equilibrium points of our biological model then we added in our model the effect of the tides in the fishing effort which maximizes the profits of the fishermen under the constraint of the conservation of the biodiversity of these marine species using the generalized Nash equilibrium in the resolution of the bioeconomic model. As results, we were able to give the best fishing times according to the tides of each month of the whole year which will allow us to achieve better yields. Hence the importance of introducing the effect of high and low tides in bioeconomic models.

Fisheries: A Missing Link in Greenhouse Gas Emission Policies in South Korea

Recent studies demonstrate that fisheries are massive contributors to global greenhouse gas (GHG) emissions. The average Korean fishing vessel is old, fuel-inefficient, and creates a large volume of emissions. Yet, there is little research on how to address the GHG emissions in Korean fisheries. This study estimated the change in GHG emissions and emission costs at different levels of fishing operations using a steady-state bioeconomic model based on the case of the Anchovy Tow Net Fishery (ATNF) and the Large Purse Seine Fishery (LPSF). We conclude that reducing the fishing efforts of the ATNF and LPSF by 37% and 8% respectively would not only eliminate negative externalities on the anchovy and mackerel stock respectively, but also mitigate emissions and emission costs in the fishing industry. To limit emissions, we propose that the Korean government reduce fishing efforts through a vessel-buyback program and set an annual catch limit. Alternatively, the government should provide loans for modernizing old fishing vessels or a subsidy for installing emission abatement equipment to reduce the excessive emissions from Korean fisheries.

Bioeconomic-Epidemiological Model of Scomber colias Population in the Moroccan Coasts

In this paper, we develop and study a mathematical model for the dynamics of Scomber colias and Thunnus thynnus prey-predator with parasitic helminths. We search to analyze a bioeconomic model in which both susceptible and infected prey populations Scomber colias are exposed to the predator Thunnus thynnus, with varying degrees of exposure. However, the predator feeds preferentially on the most numerous prey types. This implies a kind of switching from the susceptible class to the infected class, and vice versa, as these two types of prey change in numerical superiority. So, the positivity, boundedness, equilibria, stability, and bioeconomic equilibrium are studied. Some numerical simulation of stability is cited. For giving a high yield and keeping the Scomber colias and Thunnus thynnus populations away from extension, we use the Maximum Principle of Pontryagin.