Impact of the extent and locality of mud patches on the density and geograpidc distribution of juvenile Agulhas sole Austroglossus pectoralis (Soleidae)

The main focus of this study was to gain an understanding of the distribution of juvenile (10–24 cm Lt ) Agulhas sole and some factors that could govern their dispersal and migration. The hypothesis that the size and the locality of mud patches determine the density and geographic distribution of juvenile sole was investigated. Data from 10 trawling surveys, between 20 and 27°E along the southern Cape coast during the period 1986–1992, were analysed to assess the density and geographic distribution of juvenile Agulhas sole. Within the distribution area of Agulhas sole there are two localities which differ widely in the size of mud patches. Agulhas sole do not appear to be dependent on estuaries as nursery grounds, but juveniles were more abundant on the extensive mud patches of open marine coastal waters of the central Agulhas Bank than in large sheltered bays, with limited patches of mud, farther east. Spawning adults were found mainly on sandy sediment close to mud patches or farther offshore. The locality of spawning, in relation to the current dynamics, suggests that, on the inner shelf of the central Agulhas Bank, spawning products would not be dispersed by the Agulhas Current. However, towards the east, spawning products could be advected eastwards and sometimes be entrained in the eddies of the Agulhas Current.