The Biology of the bronze bream, Pachymetopon grande (Teleostei: Sparidae) from the south-east Cape coast, South Africa

Abstract

The biology of the sparid fish, Pachymetopon grande, was investigated from data collected on the southeastern Cape coast between August 1984 and March 1987. Sectioned sagittal otoliths revealed that they are a slow-growing, long-lived species capable of reaching ages in excess of 40 years. Detailed histological examination of gonadal development showed that they are rudimentary hermaphrodites, males and females maturing after a non-functional intersexual stage. The breeding season is restricted to between January and June, and observations suggest that they are group spawners with pelagic eggs. Maturity was reached at 300 mm fork length or approximately 5,5 years old. P.grande is primarily herbivorous, feeding selectively on rhodophytes found on inshore reefs down to approximately 20 m. Minor dietary components included hydrozoans, octocorals and other small invertebrates. Macroalgal degradation by gut endosymbbnts or the utilization of macroalgal epibionts was not evident, suggesting that storage and extracellular carbohydrates of the macroalgae were utilized in the diet. The importance of P.grande to the inshore recreational angling fishery, together with certain aspects of its biology, underline the need for conservation measures aimed at ensuring the sustainability of this resource.