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¹ Shanghai Ocean University, College of Marine Sciences, The Key Laboratory of Shanghai Education Commission for Oceanic Fisheries Resources Exploitation, Shanghai 201306, China
² Ministry of Education, The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources (Shanghai Ocean University), Shanghai 201306, China DOI : 10.4194/trjfas.2011.0119 Viewed : 4284 - Downloaded : 4553 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 (L₅₀) 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 L50. 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 L50 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 L₅₀ in the TAO (119.5 cm) was larger than that in the WCTIO (117.7 cm). The Akaike’s information criterion showed that the Lysack’s (1980) model can be accepted as the best model for estimating L₅₀ of bigeye tuna. Keywords : Bigeye tuna, Thunnus obesus, size at sexual maturity, reproduction