Age estimation of commercially exploited fish species in the Benguella region. Stocks of the two species of horse mackerel that occur in the Benguela region, namely Cape (Trachurus trachurus capensis) and Cunene horse mackerel (Trachurus trecae) are being exposed to increasing levels of commercial exploitation, highlighting the requirement for effective management measures to ensure their sustainable utilization. Such measures can only be implemented with confidence if they are based on reliable stock assessment procedures. Sizestructured stock assessment models have been found to be unsuitable for Southern African horse mackerel stocks, and the decision has recently been made to move to an age-structured VPA approach. A fundamental requirement for this approach to stock assessment is the availability of robust information concerning the age structure of the population(s).