Abstract
The dominant large-scale oceanographic feature along the east coast of southern Africa is the Agulhas Current Ecosystem, a western boundary current that forms part of the anticyclonic Indian Ocean gyre. The average course of the core of the current, which flows southwestward at speeds greater than 1 ms super(-1), follows the edge of the continental shelf, moving further from the coast as the shelf widens to form the extensive Agulhas Bank off the southern tip of Africa. Several studies have suggested that the Agulhas Current Ecosystem is responsible for the dispersal of the early life history stages of various fish species, and to test this hypothesis three extensive cruises were conducted in the southwest Indian Ocean during 1990/91. Spatial and temporal oceanographic features of the region are presented and correlated with composition and abundance of the ichthyoplankton assemblage. In general, concentration of larvae decreased offshore and there were marked differences in ichthyoplankton composition between stations on the continental shelf and offshore in the Agulhas Current Ecosystem. Larvae of clupeoids, myctophids, and some economically important perciform families are considered, and their observed distribution patterns are related to possible dispersal mechanisms.