Growth and longevity in acanthurid fishes; an analysis of otolith increments

TLDR: Acanthurid fishes from eastern Australia appear to have consistent patterns of growth and longevity despite marked differences in asymptotic size, diet and mode of life.

Abstract: Increments in the sagittal otoliths from 10 species of acanthurid fishes from eastern Australian coral reefs were used to estimate age The species included representatives of 5 genera: Acanthurus lineatus, A. olivaceus. Ctenochaetus strlatus, Zebrasorna scopas, Naso brevirostris, N. hexacanthus, N. tuberosus, N. unicornjs, N. vlam~ngil, and Prionurus rnaculatus. Systematic increments consisting of alternating opaque and translucent bands were observed in the sectioned sagittae of all 10 species. Regression of numbers of increments on sagittal weights revealed consistent linear relationships between these variables in all species examined indicating continuous growth in sagittal thickness over the life span For A. lineatus, A olivaceus, C stnatus and Z scopas recapture of specimens injected with tetracycline confirmed an annual pattern in increment formation with an opaque band being formed in early austral summer. Size at age plots revealed cons~stent growth patterns and life spans. All species examined had life spans of 30 to 45 yr in which rapid initial growth over 3 to 4 yr was followed by extended periods of asymptotic growth. In these species up to 80% of linear growth was dccomphshed in the initial 1 5 " # ~ of the life span. Analysis of otoliths from the 5 species of A'aso and P maculatus, while not validated, revealed similar incrt,n~ent distributions within the sagitta, similar relationships between increment number and otolith weight, and similar slze at age plots Acanthurid fishes from eastern Australia appear to have consistent patterns of growth and longevity despite marked differences in asymptotic size, diet and mode of life.