Japanese longline CPUE for yellowfin tuna in the Indian Ocean standardized by generalized linear model

Japanese longline CPUE for yellowfin tuna in the Indian Ocean (area aggregated and area-specific) was standardized up to 2017 by GLM mainly based on similar methods used in the previous studies. Basically, standardized CPUEs showed similar trends among areas. CPUE continuously decreased from 1950s to around 1974, and kept in the same level until 1990. Thereafter, it declined to a historically low level and then slightly increased in recent years. A vessel effect was also used in a part of analyses, and it has some extent of influence on CPUE trend. Decline in CPUE got less steep by using the vessel effect. There was somewhat difference between the trend of CPUEs in this study and those created in the collaborative analysis (with cluster analysis and vessel ID).