The population structure and growth of juvenile Rhabdosargus holubi (Steindachner) (Teleostei: Sparidae) in a closed estuary

The population structure and growth rate of Rhabdosargus holubi (Steindachner) in the closed West Kleinemond estuary in south east Africa, from 1971–973, are described. Juvenile R. holubi invade the estuary at a length of 1–2 cm but migrate back to the sea at a length of about 14 cm without attaining maturity in the estuary. Adult R. holubi are rarely encountered in estuaries. The annual growth increment of O group R. holubi was 6 cm, almost all occurring in summer. The growth of Lithognathus lithognathus (Cuvier) was also measured in the same closed estuary and O group fish of this species also grew 6 cm per annum although 1 + fish grew 8 cm per annum.