Size at Sexual Maturity of Bigeye Tuna Thunnus obesus (Perciformes: Scombridae) in the Tropical Waters: a Comparative Analysis

摘要

The size and proportions of bigeye tuna reach maturity in the stock is an important reference for decision making in fisheries management. The size at 50% sexual maturity (L-50) of bigeye tuna, Thunnus obesus, was investigated, the data was taken from the 1,042 sampling fish caught from the tropical Atlantic Ocean (TAO), 1,313 from the west-central tropical Indian Ocean (WCTIO) and 391 from the Eastern and Central Tropical Pacific Ocean (ECTPO) and five common models were used for estimating the parameter L-50. The results showed that the observed minimum fork length that attained sexual maturity for female (male) bigeye tuna in the TAO, female (male) bigeye tuna in the WCTIO, and female bigeye tuna in the ECTPO to be around 104 cm (108 cm), 110 cm (110 cm) and 94 cm, respectively. The estimated L-50 of female bigeye tuna in the TAO, the WCTIO and the ECTPO were 117.7 cm, 119.3 cm and 117.5 cm respectively. However, for male bigeye tuna, the estimated L-50 in the TAO (119.5 cm) was larger than that in the WCTIO (117.7 cm). The Akaike's information enter ion showed that the Lysack's (1980) model can be accepted as the best model for estimating L-50 of bigeye tuna.