Optimum harvesting scenarios for the management of the bigeye tuna Thunnus obesus at the Eastern Pacific Ocean

摘要

Catch and effort data of the tuna purse seine fishery and biological and socio-economic parameters of bigeye tuna (Thunnus obesus) in the Eastern Pacific Ocean were used to reconstruct the population structure for 1995-2009. The fishing mortality in recent years indicates a growing pressure on the stock, but it was found slightly under exploited. By increasing the fishing mortality would allow attaining the Maximum Sustainable Yield (MSY). The Maximum Economic Yield (MEY) can be achieved by reducing the fishing mortality rate. With a reduction of the fishing mortality in 20 per year, the stock could be restored and the benefit/cost ratio could increase allowing a sustainable fishery. Results of the simulations suggest that the best harvesting strategy to adopt would be at the MEY, which imply several benefits and a few inconvenient social and economic costs, which after a comparison with the current condition, seems to be quite acceptable. If adopted, it is convenient to apply it gradually to avoid undesirable impact from the social point of view, because it would imply a reduction of nearly 7 of the fishermen. The economic benefit would have a significant increase over 20, these surplus income could be used to finance other economic activities to provide employment to the fishermen leaving this activity.