Application Of A Bioeconomic Model To The Fishery Of Yellowfin Tuna Thunnus Albacares In The Eastern Pacific Ocean

A measure of technological efficiency, tuna catch per ton of carrying capacity is used, based on yellowfin tuna, Thunnus albacares, captured in the Commission's Yellowfin Regulatory Area (CYRA), as well as on number and carrying capacity of the fishing vessels, during the period 1971-1987. It is observed that the Mexican tuna fleet has been more efficient than the mean of the international fleet. The abundance index since 1980 has a maximum in 1986, with a declining trend afterwards. With the Schaefer and Fox production models, sustainable yield curves are produced. It is considered that the maximum sustainable yield estimate obtained with the Fox model is correct due to the present condition of the resource but that the one calculated with the Schaefer model is a better one in the long run. With operation costs and the international price for tuna in 1987, a static bioeconomic model is applied, locating the maximum economic yield and open access points. It is observed that the effort applied since 1983 has not varied too much, corresponding to the open access equilibrium effort obtained with the production models.