Age validation, growth and population characteristics of greenback flounder (Rhombosolea tapirina) in a large temperate estuary

Abstract

The greenback flounder (Rhombosolea tapirina) is an important fishery species in southern Australia and New Zealand, whose demographic processes are poorly understood. This study developed an ageing protocol based on otolith interpretation and provided estimates of age-based data for an exploited population in the estuary of Australia's largest river system. The otoliths fulfilled three criteria that established their usefulness for ageing. Estimates of size and age were used to generate von Bertalanffy growth curves for male and female fish sampled from two areas within the estuary. There were no differences in growth between the sexes, despite the strong bias in number towards female fish. Spatial differences in growth were marginal. Populations involved only a few young age classes. Such truncation may relate to the fishery, to movement of older fish out of the system, or to recent poor environmental conditions limiting spawning and early life survivorship.