Sibusiso Yokwana

MSc Candidate
Sibusiso Yokwana


Genetic stock structure of the Blue bream (Pachymetopon auneum), an important linefish species in South Africa.

Large populations of fish rarely mate throughout their range, but rather form a series of discrete, structured populations or stocks, which may respond differently to harvesting.

The Blue bream Pachymetopon auneum (Val.) is a sparid, endemic to southern African waters, and is common along inshore rocky reefs and kelp beds. Studies have suggested that the species is highly resident. Considering its life-history, this residency may make the species sensitive to overexploitation, being a significant species in the linefishery sector

A comprehensive assessment of genetic stock structure is needed, such that

  • appropriate management measures can be put in place, and stocks and genetic integrity can be preserved, and
  • any reductions in genetic variability caused by overexploitation can be detected.

This study aims to evaluate the genetic stock structure of Blue bream, determining whether the species exists as a single or as multiple stocks. Specific objectives are:

  • to identify, using mitochondrial sequence data and microsatellite data, the degree and distribution of genetic variation across the species’ distribution,
  • to determine the level of differentiation among stocks, if present, and identify potential barriers to gene flow, and
  • to provide information to fisheries management to enable the protection of natural populations.

Registered: University of Fort Hare (Department of Zoology and Entomology)

Supervisor: Dr Gavin Gouws (SAIAB)
Co-supervisor: Dr Niall Vine (Department of Zoology and Entomology, University of Fort Hare)