Distributional and dietary overlap between two common squaloid sharks, squalus acutipinnis and squalus bassi, caught as bycatch off the coast of South Africa

Abstract

Squalus acutipinnis and S. bassi may be the most common dogfish species around South Africa, and show overlap in their latitudinal and bathymetric distributions. Even though these sharks are likely endemics, they are also the common bycatch species and still, species-specific studies are lacking. The overall objective of this thesis was to understand the intraspecific and interspecific variability in the distribution and feeding ecology of these two species around the West and South coasts of South Africa. All species catch records and samples were collected during routine demersal hake biomass research surveys, conducted by the Department of Forestry Fisheries and the Environment (DFFE). Distributional patterns were evaluated using catch records, dating from 1984 to 2015. These results indicated that S. acutipinnis were commonly caught on the South coast whereas S. bassi was more abundant on the West coast.