Pacific Bluefin Tuna (PBF) are caught by the tuna longline fishing vessels in the offshore waters of Taiwan. The fishing seasons of PBF are in the May and June. The annual catches in number of PBF ranged from 713 (in 2012) to 8,193 (in 2003). There is an increasing trend in total catch recently, because large number of smaller individual (180-220 cm in fork length) caught by Taiwanese small-scale longline vessel during 2014-2017. The best-fitted general linear model selected by AIC and Chi-squared is Model 4: Zero-inflated with possion distribution. The standardized CPUE shows similar trends with nominal CPUE in 2005-2017. The annual nominal CPUE range from 0.09 (1/1000 Hooks) in 2012, to 0.31(1/1000 Hooks) in 2003.