Age and growth of Rhabdosargus sarba (Pisces: Sparidae), from KwaZulu-Natal, South Africa

Abstract

Age and growth of Rhabdosargus sarba, sampled along the KwaZulu-Natal coast was estimated by counting the number of growth rings in sectioned sagittal otoliths read under transmitted light. The reproducibility of otolith readings was described by the average percentage error index, which was equal to 4.7%. Validation of the annual periodicity of growth zone deposition was achieved through marginal zone analysis and oxytetracycline labeling of captive fish. The age-length data from the sample of 216 fish was best described by the special Von Bertalanffy growth function of the form: L t=715 mm FL (1−e −0.16/ year (t+0.996 years) ) Like most sparids, R. sarba is a slow growing, long-lived species. The study revealed a maximum age of 16+ years and, based on previously published data, the age-at-maturity was estimated to be 1.8 years.