Marine ecosystem variability and human community responses: The example of Ghana, West Africa

This study describes variability in the marine ecosystem of Ghana, West Africa, on several temporal and spatial scales and discusses how the human communities using this ecosystem respond to this variability to cope socially and economically. Ghanaian marine waters are part of an upwelling system with strong seasonal and inter-annual variability. Much of this variability is forced at large spatial scales in the tropical Atlantic and by El Niño--Southern Oscillation events in the Pacific Ocean, which influence inter-annual variability of sea surface temperature and pelagic fish landings off Ghana. At decadal scales, Ghanaian marine waters experienced cool sea temperatures and low fishery landings during the 1960s, rapid warming and increases in fishery landings during the late 1970s and 1980s, and variable temperatures and fishery landings during the 1990s. In the late 1990s, pelagic and demersal fish populations appeared to be declining, partly due to over-fishing, although the per capita supply (domestic production plus net imports) of fish was kept high by increased imports. Artisanal fishers and fishing communities in Ghana have devised strategies to deal with variability on seasonal and inter-annual scales. These livelihood strategies include: (i) exploiting marine and terrestrial natural resources more intensively, initially at local scales but expanding to regional scales; (ii) ensuring multiple and diversified income sources; (iii) investing in social relationships and communities for support; and (iv) undertaking seasonal or permanent migrations. In addition, the national government imports fish to deal with shortages. However, these strategies may be less adapted to variability at decadal scales, and may not be sustainable when viewed at the larger scales of environmental change.