Growth and longevity in fishes of the family Scaridae

Systematic check-marks In the sagittal otollths from 6 species of scarids sampled fl-om the Great Bar~ier Reef, Australia, were used to develop size-at-age plots. The species were Chlorurus gibbus, C. sordidus, Scarus frenatus, S. niger. S. psittacus and S. nvulatus. Comparative information for a seventh specles, S. schelgeli, for which otolith increment data \*ere ava~lable. was also included. Systematic check-marks in the form of alternating opaque and translucent bands were observed in the sectloned sagittae of all species. Regression of numbers of sagittal increments on sagittal weights revealed consistent llnear relationships between these var~ables indicating continuous growth In sagittal thickness over the llfe span. For C. sordldus, S, frenatus, S nlger and S. r~vulatus recapture of specimens injected wlth tetracycline conf~rmed an annual pattern In Increment formation, with an opaque band being formed in early summer. Additlonal confirmation of the annual formation of opaque increments in S. rivulatus was obtained by marglnal Increment analysis. Size-at-age plots identified variable growth patterns and longevities among the 7 species. Growth in C. gibbus, S. psittacus, S. schelgeli and S r~vulat i~s was continuous wlth little evidence of an as\,niptotic size. I ifc spans ranged from 5 yr ( S . psittacus) to 14 yr (C glbbus). In C. sordidus, S. frenatus dnd S. niger thcrc, were clear asymptot~c slzes achieved early In 11fe and greater longevltles (10 to 20 yr). All species were protogynous with evidence of sex-specific growth patterns. Transition to the terminal male ~dent l ty was associated with enhanced growth resulting in larger and younger terminal males than females of equivalent size.