ABSTRACT
Southern bluefin tuna (Thunnus maccoyii, SBT) are a highly migratory tuna species that occur in waters of the eastern Atlantic, Indian and South-west Pacific Oceans between 30°S and 50°S (Caton 1991). Mature fish migrate to a single spawning ground located in the North-east Indian Ocean between Java and Australia (Farley and Davis 1998; Patterson et al. 2008). After a larval stage, juveniles leave the spawning ground, move down the west coast of Australia and reach the south coast by age one where they spend the austral summer. Up until approximately five years of age, juvenile fish undertake annual cyclical migrations in which they generally spend austral summers in the Great Australian Bight (GAB), and move east as far as New Zealand or west as far as South Africa during the winter (Bestley et al. 2008; Basson et al. 2012). Fish older than five years rarely return to the GAB and disperse widely across the southern oceans from the western Atlantic across the Indian Ocean to the Tasman Sea. SBT are estimated to reach maturity at 10–12 years and can live to more than 40 years (Shimose and Farley this volume).
