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Biophysical Characteristics

Environmental forcing and fisheries resources in Côte d’Ivoire and Ghana: Did something happen?


The main environmental characteristics off the coasts of Côte d’Ivoire and Ghana are reviewed. Seasonal variability as well as long-term environmental changes observed during the last three decades are presented using a seasonal-trend decomposition procedure. Striking similarities are observed between changes in the Gulf of Guinea and the Pacific. This suggests that the observed changes are not the result of local processes but rather are induced by inter-oceanic teleconnection via the atmosphere. Fisheries productivity in the Gulf of Guinea appears to be quite important but is limited by the duration of the upwelling process. Thus, using comparative methods between several upwelling systems, relationships are identified between pelagic productivity and several environmental factors (wind, turbulence, and upwelling index) and only a weak relationship is observed when considering the demersal fish productivity and the upwelling intensity. Fisheries as a whole off Ghana and Côte d’Ivoire have been expanding during the last four decades: the total marine fish catch off Côte d’Ivoire and Ghana has been increasing from less than 50 thousand tonnes in the 1950s to around 400 thousand tonnes in the mid-1990s. For the pelagic species, there has been a noticeable increasing trend is observed since the 1950s and the total catch reached about 250 thousand tonnes in the 1990s. By contrast, the demersal fisheries in Côte d’Ivoire and Ghana have fluctuated between 30 and 50 thousand tonnes since the mid-1960s without any trend. Fishing effort by purse-seiners and trawlers has decreased significantly since the 1970s in Côte d’Ivoire. The abundance, estimated from cpue of both pelagic and demersal, does not appear to be related to fishing activity. Trends in several environmental time series are in phase with the observed trends in the CPUE data of the demersal fisheries in Côte d’Ivoire. This suggests that in Côte d’Ivoire the abundance of the demersal fish stock is strongly related to large scale environmental changes.

 

Read full paper https://doi.org/10.1016/S1570-0461(02)80040-4.

Name of Author(s):
P. Cury, C. Roy
Institutional Affiliation:
Type of Publication:
Book Section
Name of Publisher or Journal:
Large Marine Ecosystems, Elsevier
Date of Publication:
2002
Number of Pages:
20