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

Abstract

Catch and effort data of the tuna purse seine fishery and biological andsocio-economic parameters of bigeye tuna (Thunnus obesus) in the EasternPacific Ocean were used to reconstruct the population structure for1995-2009. The fishing mortality in recent years indicates a growingpressure on the stock, but it was found slightly under exploited. Byincreasing the fishing mortality would allow attaining the MaximumSustainable Yield (MSY). The Maximum Economic Yield (MEY) can beachieved by reducing the fishing mortality rate. With a reduction of thefishing mortality in 20% per year, the stock could be restored and thebenefit/cost ratio could increase allowing a sustainable fishery.Results of the simulations suggest that the best harvesting strategy toadopt would be at the MEY, which imply several benefits and a fewinconvenient social and economic costs, which after a comparison withthe current condition, seems to be quite acceptable. If adopted, it isconvenient to apply it gradually to avoid undesirable impact from thesocial point of view, because it would imply a reduction of nearly 7%of the fishermen. The economic benefit would have a significant increaseover 20%, these surplus income could be used to finance other economicactivities to provide employment to the fishermen leaving this activity.