Distribution and reproduction of the reef fish Petrus rupestris (Pisces: Sparidae) off the coast of South Africa

Abstract

The red steenbras (Petrus rupestris) is endemic to the south and south-east coasts of South Africa and is the largest member of the family Sparidae. Morphometric relationships between length and mass are given for whole and eviscerated fish. The size distribution of P. rupestris is related to locality and water depth. Juveniles and sub-adults are common in shallow (< 50 m) Cape waters between False Bay and East London. Adults are more common offshore, in deep waters (> 50 m), especially off the coast between East London and Coffee Bay, throughout the year. P. rupestris were found to be rudimentary hermaphrodites. The development of the functional sexes, and the occurrence of sexual dichromatism, are described. Sexual maturity is attained at about 575 mm fork length in those fishes in the spawning areas. Reproductively ripe fishes were taken from Transkei, East London and a small collection was made from the Agulhas Bank. Peak spawning is between August and October. Current management regulations are discussed and advantages of large marine reserves in conservation of this mobile apex predator are outlined.