Towards an appropriate economic management regime of tuna fisheries in Ghana

Abstract

The Ghanaian tuna fishery is a baitboat and purse seine fishery. Three main species of tuna are caught namely, Skipjack, Bigeye and Yellowfin. A detailed and comprehensive set of catch and effort data for the tuna fisheries has been obtained for the period 1980-2001. Harvest functions have been designed and estimated. By maximising the loglikelihood function by numerical methods, parameter estimates and performance indicators of the different models were obtained. The best result was obtained for a harvest model allowing inclusion of a time trend parameter. For this model the stockoutput elasticity is assumed to be 1, the effort-output elasticity is estimated at 0.849, and the technological change at about 3.6% annual increase in productivity. Technical – Economic interactions among the species have been analysed. Different periods where chosen for each period, cross – elasticity of supply calculated between the species. The result indicated a mixed significance, which gives room for the existence of technical – economic interactions among the species over the years, considered. This suggests that single species management may be inappropriate for the tuna fishery.