A Preliminary Investigation of Age and Growth of Otolithes ruber from KwaZulu-Natal, South Africa

Abstract

This study investigated age and growth of Otolithes ruber, found in KwaZulu-Natal, South Africa. The specimens were collected from prawn trawlers that operate off the shallow water Tugela Bank and from a recreational boat fishery in Durban. Estimates of age and growth parameters were based on the examination of sectioned sagittal otoliths. There was difficulty in estimating growth parameters for separate sexes because the small fish were not sexed and the numbers of males was low. Periodicity of growth zone formation was assumed to be annual although periodicity of growth zone deposition could not be established by marginal zone analysis. The von Bertalanffy growth curve was used to describe the combined male and female growth of O. ruber: Lt = 419mm TL (1-e-0.31 (t+0.96)) The maximum age estimated was eight years. The repeatability of the age estimates was relatively high (Average Percentage Error: 12.5%). The information gathered from this study will be used in a subsequent stock assessment.