Standardizing CPUE of Albacore Tuna (Thunnus alalonga Bonnaterre, 1788) on Tuna Longline Fishery in Eastern Indian Ocean

Albacore (Thunnus alalunga) is the third dominant catch of Indonesian tuna longline fishery operating in the eastern Indian Ocean. The percentage production of albacore catch was reaching up 6% of the total catch of tuna groups in Indonesia. This study aims to examine a relative abundance indices using standardized catch per unit of effort (CPUE) of longliner based on albacore tuna. This information will give a valuable input and information to support stock assessment particularly in the regional basis. In this study, we use Generalized Linear Model (GLM) with Tweedie distribution to standardize the CPUE and to estimate relative abundance indices based on the Indonesian longline dataset time series. Data were collected from January 2006 to December 2018 (2,811 data sets) by conducting direct onboard observation on tuna longline vessels operating in the Indian Ocean. The result show that year, area, hooks between floats significantly influenced the nominal CPUE of albacore. CPUE standardization of ALB in the periods of 2006 to 2014 was tend to be stable and increase from year to year but in 2015 to 2018 the CPUE standardization tend to be unstable and fluctuate due to changes in fishing patterns and changes in the area of onboard observer program.