Reproductive Biology of Snapper (Pagrus auratus) in Subtropical Areas of Its Range and Management Implications of Reproductive Differences with Temperate Populations

Snapper (Pagrus auratus) (Bloch and Schneider) sampled from the waters of the Queensland east coast (20 degree to 28 degree S) spawned from June to October, at least three months earlier than the New Zealand snapper (36 degree to 44 degree S) and snapper from other temperate latitudes. The size at which snapper reached sexual maturity (26 to 30 cm FL) was broadly similar to other more temperate areas. However, the apparent faster growth rate of tropical snapper enabled them to reach sexual maturity at less than 2 years of age, more than a year earlier than in more temperate latitudes. This suggests that the attainment of sexual maturity in snapper is more likely to be based on size than age. There were also fish as old as 5 years that had not yet matured. No specific snapper spawning grounds were sampled and snapper with ripe gonads were found throughout the species distribution in Queensland. Snapper mainly spawned in the evening and early morning. The timing of the spawning season relative to the timing of the winter growth check formation may be partially responsible for the difficulty in interpreting snapper otoliths in subtropical areas.