Age structure and growth in a large teleost, Cheilinus undulatus, with a review of size distribution in labrid fishes

Abstract

Age-based demographic parameters were estimated from 164 individuals of the large teleost Cheilinus undulatus from NE Australia. Analysis of sagittal otoliths revealed alternating translucent and opaque bands in which annual periodicity of a single opaque band was confirmed. A size-at-age plot of 164 individuals showed that males grew significantly faster than females, achieving a size of 140 cm fork length (FL). Male growth trajectories were essentially linear. Maximum ages recorded were 25 yr for males and 30 yr for females. Estimates of annual total mortality ranged from 0.10 to 0.14. The age distribution of males suggests protogyny with male recruitment into the population commencing at 9 yr at a size threshold of 70 cm. The age distribution of females confirmed that not all individuals changed sex. Analysis of the sample size revealed a strongly skewed distribution with a modal size peak at 50 to 70 cm and an extended tail of larger individuals. Estimates of size distributions from underwater surveys revealed a right-skewed distribution similar to that observed in our sample. An analysis of size distributions in labrid fishes shows that large size (>75.0 cm FL) is rare (4.5% of 559 species). Demographic analysis of C. undulatus and of large labrid fishes demonstrates that they share a dynamic demography with fast indeterminate growth rates and relatively short life spans.