Age, growth and mortality of redfish Centroberyx affinis

Age and growth of 5678 redfish, collected during 1991-98 from Australia's S outh East Fishery, were estimated from thin sections of otoliths. A maximum age of 44 years was recorded for a 30 cm (fork length) female, but 80% of females in the commercial catch were <10 years, and 80% of males were <13 y ears. The largest was a 34 cm female estimated to be 36 years old. Repeated age estimates of a subsample revealed an average error of 3.79%. There was significant variation in the mean length-at-age among years, and there wer e significant effects for age*year, age*sex, age*region, region*year, and s ex*region*year interactions. Assessments of the fishery have assumed a sing le stock, because tagging results from the 1980s indicate movement of redfi sh along the coast. This study found consistent differences in sex ratio an d growth rate between regions, which indicate some structuring within the p opulation. However, the differences in growth rates are not consistent amon g years and could not be explained by differences in depths fished, suggest ing a more dynamic situation than spatially segregated stocks. Estimates of natural mortality ranged from 0.07 to 0.11 year(-1) and differed between r egions.