Influencia de la Corriente de Canarias en el ciclo vital de Pagellus acarne (Fam. Sparidae) en el Banco Canario Sahariano

Resumen

lnfluence of the Canary Current upon the life history of Pagellus acarne (Fam. Sparidae)
on the Salaarian fishing grounds
This paper deals with the influence of the Canary Current upon the life history of Pagellus acarne, a species belonging to the family Sparidae, a demersal fish group very common on the northwest African grounds.
We propose a new model for the spatial distribution of this species in the studied area (From Cabo Bojador -26º 10′ N.- to Punta Durnord -23º 39′ N), based on the transport by the Current of the non swimming stages (eggs and early larvae).
The Canary Current flowing southward hits the raising shelf -at 25º 20′ N.- where it is forced to spread over the shelf and nuxing part of the deeper water with the surface flow. Due to the shape of the shelf and other factors (favorable winds, etc.) the flow lines are compressed and the speed over the shelf increases causing a strong divergence and upwelling. A narrow arm of the Current develops close to the coast line with a small westward omponent due to friction with the sallow bottom.
A population of adult individuals, without juvenile or young tsages, lies near Cabo Bojador, showing a small range migration to the coast at the breeding season. The eggs produced by this population are carried south and westward by the Current. An important nursery appears in autumn near 20°N. The link between the two populations (adults and youngs) might be the eggs and larvae carried by the narrow arm of the Current driven along the coast line, since in all our observations no specirnen was found at any stage betwcen the two populations except severa1 adult shoals scattered over the outer border of the shelf.
The reverse link between the young and the parenta1 populations is assumed to be a countercurrent migration (continous or occasional) over the externa1 border of the shelf whcre a scattered population of preadults and adults exists. A second hypothesis might be the migration of old individuals from thc Morocco coast. However this hypothesis has been rejected since it would not explain the strong size selection.
For the preadult and adult population centered in the south part of the area studied, the same model can be applied, considering that the eggs are carried south and out of the studied region.