GROWTH AND LONGEVITY IN FISHES OF THE FAMILY SCARIDAE

Systematic check-marks in the sagittal otoliths from 6 species of scar ids sampled from the Great Barrier Reef, Australia, were used to devel op size-at-age plots. The species were Chlorurus gibbus, C. sordidus, Scarus frenatus, S. niger, S. psittacus and S. rivulatus. Comparative information for a seventh species, S. schelgeli, for which otolith inc rement data were available, was also included. Systematic check-marks in the form of alternating opaque and translucent bands were observed in the sectioned sagittae of all species. Regression of numbers of sag ittal increments on sagittal weights revealed consistent linear relati onships between these variables indicating continuous growth in sagitt al thickness over the life span. For C. sordidus, S. frenatus, S. nige r and S. rivulatus recapture of specimens injected with tetracycline c onfirmed an annual pattern in increment formation, with an opaque band being formed in early summer. Additional confirmation of the annual f ormation of opaque increments in S. rivulatus was obtained by marginal increment analysis. Size-at-age plots identified variable growth patt erns and longevities among the 7 species. Growth in C. gibbus, S. psit tacus, S. schelgeli and S, rivulatus was continuous with little eviden ce of an asymptotic size. Life spans ranged from 5 yr (S. psittacus) t o 14 yr (C, gibbus). In C, sordidus, S. frenatus and S. niger there we re clear asymptotic sizes achieved early in life and greater longeviti es (10 to 20 yr). All species were protogynous with evidence of sex-sp ecific growth patterns. Transition to the terminal male identity was a ssociated with enhanced growth resulting in larger and younger termina l males than females of equivalent size.