Standardization of catch rates for Striped marlin (Tetrapturus audax) and Blue marlin (Makaira mazara) in the Indian Ocean by the core fishing area approach using operational catch and effort data of the Japanese tuna longline fisheries

We attempted the core fishing area approach and the new area effect concept incorporating environmental data, in order to evaluate standardized catch rates for Striped marlin (Tetrapturus audax) and Blue marlin (Makaira mazara) in the Indian Ocean. We used operational catch and effort data of the Japanese tuna longline fisheries (1971-2012). We discussed pros and cons on the core fishing area approach and the new area effect concept by comparing results from last year.