Regional patterns in reproductive biology of Lethrinus miniatus on the Great Barrier Reef

Abstract

Uniformity in fish population biology is a common assumption in many fishery assessments and management arrangements. Although spatial patterns in population biology are often unknown, ignorance of significant variation within a fished stock has profound implications for fishery assessments and management. In the current paper, the reproductive biology of an exploited reef fish, Lethrinus miniatus, was examined for populations in the northern and southern regions of the Great Barrier Reef (GBR). Significant regional variation was observed in some reproductive parameters, but not others. In the northern region, the proportion of spawning females observed during the spawning season was significantly greater and the size at sex change significantly smaller than in the southern region. However, the spawning season, age at sex change and sex ratios did not differ significantly between the northern and southern regions. Size and age at maturity could not be estimated from either of these regions, but an estimate was obtained from the Capricorn–Bunker region at the southern tip of the GBR. The observed regional patterns in reproductive biology of L. miniatus populations have important implications for specific management arrangements such as size limits and seasonal closures, and for fisheries management in general.