This is a recapitulation of the hypotheses already put forward on the nature of the stocks of the different species.
From the beginning of the fishery until recent years, the concepts on the structure of the stocks of the round sardinella exploited in the Côte d'Ivoire-Benin zone have evolved considerably without leading to any particular hypothesis which could today be considered as definitive. If the first working group (ORSTOM, 1976) considered a unit stock centred in Ghana and spreading to the east of Côte d'Ivoire under cover of the major upwelling, the recent development of the fishery of this species in the west of Côte d'Ivoire and an important sustained abundance in Ghana necessitated a recourse to new theories:
Since the 1987 working group (FAO, 1988), the basin theory formulated by MacCall (1983), has been taken to explain the development of a biomass of the round sardinella in this region a priori from hydroclimatic considerations.
The analysis of acoustic survey data and reasoning concerning the reproduction zones led Marchal (1991) to put forward the hypothesis which implies that a residual population may have always existed on the east of Cape Palmas or have developed in recent years due to favourable hydroclimatic conditions.
The difference between the length of the round sardinella fished in Côte d'Ivoire and that fished in Ghana correspond to this hypothesis.
The theory of the existence of stocks of S. maderensis in “strings” along the coast of the Gulf of Guinea has been neither confirmed nor refuted to date.
Little is known about the stocks of these two species; chub mackerel seems to exist in all four countries concerned but is only accessible during brief incursions over the continental shelf essentially in the major cold season. Anchovy is fished equally in the four countries but does not constitute a resource which is truly exploited except in Ghana and Togo.
