CPUE standardization of striped marlin (Kajikia audax) caught by Taiwanese longline fishery in the Indian Ocean for 1995 to 2011

This study provided a CPUE standardization of striped marlin (Kajikia audax) caught by the Taiwanese longline fishery in the Indian Ocean for time periods of 1980-2011 and 1995-2011. The delta-lognormal GLM model is adopted to perform the CPUE standardization analysis since blue marlin is caught by Taiwanese longline fleet as bycatch species and large amount of zero catches are recorded in the operational data sets. The results indicate that the influence of incorporating environmental effects on CPUE standardization is not significant for striped marlin in the Indian Ocean. The CPUEs in Area MONS and Coastal area revealed similar trends and they substantially decreased since 1980 although the CPUE obviously fluctuated in early years. The CPUE in Area ISSG fluctuated before 1990, substantially increased between 1990 and 1995, and sharply decreased thereafter. In recent years, CPUEs obviously increased for all three areas. The area-aggregated CPUE obviously fluctuated before 1995 and it revealed obvious and continuous decline trend thereafter, while it slightly increased in recent two years.