Abstract
de Bruyn, P. A., Moloney, C. L., and Schleyer, M. H. 2009. Application of age-structured production models to assess oyster Striostrea margaritacea populations managed by rotational harvesting in KwaZulu-Natal, South Africa. – ICES Journal of Masrine Science, 66: 408–419. Oysters have been harvested in KwaZulu-Natal for more than a century, by both commercial and recreational users. However, management of the resource has been based on ad hoc measures rather than quantitative, defensible management plans. Early in the history of the fishery, a rotational harvesting strategy was employed, but it has changed over time. At present, there are 10 management zones, each fished 2 years out of five, and recreational harvesting is allowed in the year preceding commercial harvesting. To assess the status of the oyster resource as well as the historical levels of exploitation, age-structured production models were applied to the oyster populations in the five North Coast management zones. The model fits to the observed data were good. Oyster abundance differed among zones, with the lowest abundance in the two most northern zones. As these zones had only recently been established, however, the paucity of data renders their assessments uncertain. The southernmost zone had the greatest oyster abundance. The benefits of rotational harvesting were demonstrated by the model outputs, which showed rapid population recovery during fallow years, suggesting sustainability of the resource. It is recommended that rotational harvesting continues to be used to manage oysters in KwaZulu-Natal.
The sustainability of small scale cane growers through youth involvement in North Coast region of Kwazulu Natal, South Africa