THE REPRODUCTIVE-BIOLOGY OF DIPLODUS-SARGUS-CAPENSIS AND DIPLODUS-CERVINUS-HOTTENTOTUS (SPARIDAE) OFF THE SOUTH-EAST CAPE COAST, SOUTH-AFRICA

An investigation of the reproductive biology of Diplodus sargus capens is and D. cervinus hottentotus was undertaken in the Tsitsikamma Natio nal Park, South Africa. Gonado-somatic indices showed that both Diplod us species had protracted spawning seasons extending from early spring into summer. The adult sex ratio of D. s. capensis was significantly dominated by females while that of D. c. hottentotus showed no signifi cant difference from a 1:1 sex ratio. Size at 50% maturity was calcula ted at 211 mm FL and 280 mm FL for D. s. capensis and D. c. hottentotu s respectively. This corresponded to an age of three and six years res pectively. A detailed histological examination of gonad development re vealed that D. s. capensis is a digynous hermaphrodite with partial pr otandry occurring in some of the male population. D. c. hottentotus is shown to be a rudimentary hermaphrodite. Group spawning behaviour in bath species is postulated based on various morphological and indirect behavioural characteristics.