Energy Metabolism of the Cattle Egret |
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| Authors: | WR Siegfried |
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| Institution: | c/o P.F.I.A.O., Zoology Department, University of Cape Town |
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| Abstract: | Ages were estimated for the tropical sparid, Acanthopagrus berda, caught in northern KwaZulu-Natal estuaries. Whole otoliths were used in the age determination. Age estimates were validated by marginal increment analysis and oxytetracycline labelling, which indicated that opaque deposition occurs primarily from September to November each year. The reproducibility of age estimates was described by a coefficient of variation of 10%. The von Bertalanffy growth curve was found to best describe the growth of A. berda. The parameters of the von Bertalanffy growth curve indicated that A. berda in northern KwaZulu-Natal is a slowgrowing species, capable of reaching at least 16 years of age. Longevity of the species, coupled with sex change, late maturation and estuarine dependency, give cause for concern for the continued sustainable utilization of this species. |
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| Keywords: | whole otoliths von Bertalanffy growth curve slow growing long-lived |
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