Contribution to the biology of the redbanded perch, Ellerkeldia huntii (Hector), with a discussion on hermaphroditism

The presence of oocytes in the testes of several males indicates that the redbanded perch Ellerkeldia huntii exhibits protogynous hermaphroditism. All males appear to be secondary in origin; however the structure of the testes differ from most other protogynous serranids. In samples collected from the Poor Knights Is., New Zealand, males outnumbered females 2.7: 1 ( n = 52). The numbers in each sex were equal until a length of 100–110 mm, after which the male proportion increased to 100%. The oldest female was aged 2+ years, whereas males were found as old as 5+ years. There were no colour differences associated with sex. The mean testes weight was only 7% of the mean ovary weight. Both sexes grew at the same rate. Observations during December indicated that although many individuals were solitary, some were paired. The larger individuals of pairs were males, the smaller females. Individuals foraged in the algal canopy on gammarid amphipods and mysid shrimps. The average range of movements was only 2·2 m².