Analysis of length data of albacore (Thunnus alalunga) caught by Taiwanese large-scale longline fishery in the Indian Ocean

In this study, historical length-frequency data of albacore caught by Taiwanese large-scale longline fishery in the Indian Ocean were explored by temporal and spatial factors. A comparison between the data recorded by the logbook data system and the scientific observer program was also conducted. Apparent different length compositions reported by logbook data were observed before and after 2003. sample sizes tended to shift from the western area to the eastern area through the years and the length distributions tended to shift to larger fishes since 2003. The length distributions from logbook data revealed greater variabilities than those from observer data, but systematic differences in the major central and dispersion tendencies by temporal and spatial factors were not significantly identified from the two data sources.