Latitudinal variation in growth rates and limited movement patterns revealed for east-coast snapper Chrysophrys auratus through long-term cooperative-tagging programs

Abstract

Understanding the spatial ecology of exploited fish stocks is key to their sustainable management. Here we used a long-term cooperative tag and recapture dataset that encompassed the entire distribution of the stock to examine patterns of movement and growth of Chrysophrys auratus (Sparidae) along eastern Australia. More than 24000 individuals were tagged, with 2117 being recaptured with information suitable for analysis of movements and 1440 with information suitable for analysis of growth rates. Individuals ranged in size between 120- and 620-mm fork length at tagging and were at liberty for up to 5.9 years before being recaptured. Results indicated population characteristics of partial migration, whereby the majority (~71%) of fish did not move any detectable distance and a small proportion (~4%) moved between 100 and 1000km. Specific growth rates were significantly affected by the latitude at tagging, with higher growth rates at lower (more northern) latitudes. Our findings suggest that Australian east-coast C. auratus are mainly resident on a subdecadal time scale and at reasonably small spatial scales. When considered with information on latitudinal variation in growth and reproductive biology, localised recruitment and a history of localised fishery declines, assessment and management at local scales may be appropriate.