A bioeconomic analysis of the Ghanaian tuna fishery (1980-2000)

Abstract

The commercial tuna fishery of the East Atlantic and like wise the Ghanaian tuna fishery are based on the harvests of Bigeye, Skipjack and Yellowfin. In Ghana, baitboats and purse seiners commercially harvest these species of tuna. This study analysed the CPUE for the Ghanaian tuna fishery. The analysis was made for the three species and also for the two vessel types. The effort was standardized to large purse seiner days. The results when compared to the CPUE per species for the East Atlantic revealed that the Ghanaian vessels (1980 – 2000) were in some cases up to 40 times more efficient than large purse seiners in the East Atlantic (1967-1980). A single species bioeconomic analysis was conducted for each of the three species using biological parameters adopted from Conrad and Adu-Asamoah (1986). This showed that present harvest levels of Skipjack and Yellowfin for the East Atlantic region were in excess of the open access equilibrium. Thus a decline in future harvest levels of Skipjack and Yellowfin is expected. Sustainable economic rents calculated for the two-vessel types revealed that, bioeconomically, baitboats are more profitable than purse seiners. It was observed that the FAD’s might be the main cause of changes in the species composition ratio of the tuna catches over the past decade.