CPUE standardization of blue marlin (Makaira nigricans) caught by Taiwanese large-scale longline fishery in the Indian Ocean

This paper briefly described the historical patterns of blue marlin catches caught by Taiwanese large-scale longline fishery in the Indian Ocean. The cluster analysis was adopted to explore the targeting of fishing operations. In addition, the CPUE standardizations were conducted using delta-general linear models with different assumptions of the error distributions. Based on the diagnostic statistics and trend of model fits, the standardized CPUE series obtained based on the delta GLM with inverse gaussian error distribution for positive catches would be recommended by this study. The results indicate that the effect of latitude provided the most significant contributions to the explanation of the variance of CPUE for positive catches and delta models for both northern areas (NW and NE), except for the year effects. The standardized CPUE series in both northern areas revealed decreasing trends in recent years.