Environmental influence on marine pelagic fish: Evidence from bioeconomic modelling

Abstract

Environmental factors other than fishing effort, contribute to influencing marine pelagic fish population dynamics and abundance. There is evidence from environmental modelling and bioeconomic analysis of the Ghanaian marine inshore pelagic fisheries. Ghana is a West African country and lies on the Greenwich Meridian. It is bordered at the South by the Gulf of Guinea. The official language of Ghana is English, but is surrounded by French speaking countries. The inshore fishery is a multi-specie, multi-fleet fishery, consisting of artisanal and inshore purse seine fleets. The coastal inhabitants depend mainly on the marine fisheries as source of employment and livelihood. Fisheries constitute 5% of Agriculture GDP. The two fisheries types in the inshore sector comprise the artisanal and inshore commercial fleet. The artisanal fleet are highly labour intensive and use dugout canoes with average engine power of 40HP. The purse seine fleet are relatively capital intensive and more commercial. The boats have wooden hull and have average horsepower of 230 HP. The average vessel capacity unit of a boat is estimated to be 136.8. Both canoes and the commercial purse seine fleet compete to exploit the same inshore pelagic fish resources within the Ghanaian EEZ. The problem is that the current stock level has dwindled and this is attributed to overexploitation and influences of the environment. Bioeconomic models using aggregated landings and effort data help to capture changes in multi-species fisheries (Hilborn and Walters, 1992). Environmental factors such as temperature and salinity are feasible when jointly incorporated in bioeconomic models. The mean monthly and annual variables and deviations from the mean are attached (Appendix A1 and A2) for comparison.