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)