Bathymetry and sediment type effects on catch rates of Austroglossus pectoralis (Soleidae) on the inner central agulhas bank

Abstract

Catch rates of Agulhas sole Austroglossus pectoralis from bottom trawls conducted during research surveys over the period 1986-1992 were compared to bathymetry and sediment types. The boundaries of sole distribution are influenced by water depth, current dynamics and the nature of the sea bed. Catch rates were significantly higher on clayey silts and sands than on sediments containing gravel. For each sediment type, catch rates were significantly higher in shallower water than in deeper water. The correlations between catch rates and water depth were consistently better in autumn than in spring. Catch rates on most sediment types were better correlated with water depth than with bottom temperature.