Reproductive biology of largehead hairtail (Trichiurus lepturus) in south-eastern Australia

Knowledge of reproductive biology and life-history traits of populations exploited by fisheries is important for their sustainable management. We investigated the life-history traits of Trichiurus lepturus (largehead hairtail) in south-eastern Australia; a region of low exploitation for this otherwise heavily exploited circumglobal species, to investigate whether there were differences in the reproductive biology and life-history traits in the south-east Australian population compared with those in other regions. We also used histological sections to examine male and female gonads at a microscopic level. Trichiurus lepturus in south-eastern Australia had a greater maximum length (193 cm total length (TL)), matured at a larger length (108 cm TL at 50% mature) and had a spawning period (March to September, Austral winter) that was inconsistent with other regions. The overall sex ratio of 1:0.4 females: males was consistent with a female dominant sex ratio observed in other regions, particularly in larger length classes. However, females in the current study dominated samples from both estuarine and coastal habitats, as well as during the spawning and non-spawning periods, which is not consistent with the patterns found in other regions. Differences in south-eastern Australia may relate to limited fishing pressure, genetic variation, or differences in environmental factors that influence reproductive development, including temperature, trophic resources and habitat.