Reproductive biology of a diandric protogynous hermaphrodite, the serranid Epinephelus andersoni

Epinephelus andersoni is a serranid endemic to south-eastern Africa. An investigation of the reproductive biology of this species from two areas along the east coast of South Africa revealed that E. andersoni exhibits several features that differ from the hermaphroditism found in most other epinepheline serranids. Among sexually mature fish, there is a complete overlap of male and female sizes and significantly more males than females. Males can develop directly from the juvenile phase as well as by sex change from functional females, although testicular morphology does not vary according to developmental pathway. Hence, the species is classified as a diandric protogynous hermaphrodite, a sexual pattern hitherto unconfirmed for the genus Epinephelus. The morphology of the gonads also differs from that of congeners, with male and female tissues being spatially distinct. A substantial part of the mature-sized component is not reproductively active, possibly because of edge-of-range effects and/or because not all individuals spawn each year. Reproduction occurs between November and January, and female total length at 50% maturity is 492 mm.