This work has been undertaken as a first attempt to evaluate the feasibility of using scarcely available information to produce coherent species assemblages maps as a tool for rational use of fishery resources. It has also been proved that these maps can be easily made with the amount of information available for Liberia, Ghana, Togo, Benin and Cameroon. It is expected that the same could be true for Congo, Gabon, Nigeria, Ivory Coast and Sierra Leone, Guinea and Guinea Bissau, using Longhurst's classification and probably further north of Senegal using Domain's classification of assemblages. The accuracy of the maps should be checked, but as high precision is not requested, great mistakes are unlikely to occur.
These maps are a graphic model of resource distribution that can readily be used. The areas covered by the assemblages in each country could be measured by planimetry. Knowing the catch by species groups would allow one to calculate and compare “extraction rates” (in tons caught/sq.km/year) for similar assemblages in different countries which may already provide useful information on levels of exploitation when combined with comparative data on average sizes, catch rates, etc.
The maps may also be used when planning to develop, for example, an artisanal fishery for, say, longline fishing on hard rocky bottoms, in order to predict species composition, relative market value of the expected species, area available for fishing and possibly potential yield (from the extraction rates obtained above).
A superimposition of these resource maps with similar maps showing the concentrations of effort1 could provide a much better idea of the heterogeneity of fishing, of the degree of coverage of the potential resource by the fishery, and possibly on the relative distribution of exploitation intensity on various assemblages. When considering resource maps in conjunction with respective effort distribution of artisanal and industrial fishermen the conflicts for competitive use of the same resource will appear in a more readily usable way for practical management than the mere observations that the two fleets land some overlapping mixture of species.
Finally, it can also be noted that the information gained on species distribution may be very useful in identifying discontinuities in stocks and potential shared stocks problems requiring joint management by two neighbouring countries.
