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Correlations between environmental factors and CPUEs of blue marlin (Makaira mazara) and striped marlin (Kajikia audax) caught by Taiwanese longline fishery in the Indian Ocean









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    Meeting
    CPUE standardization of striped marlin (Kajikia audax) caught by Taiwanese longline fishery in the Indian Ocean for 1995 to 2011 2013
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    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 alysis since blue marlin is caught by Taiwanese longline fleet as bycatch species and large amount of zero catches are recorded in the operatiol data sets. The results indicate that the influence of incorporating environmental effects on CP UE 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 rev ealed obvious and continuous decline trend thereafter, while it slightly increased in recent two years.
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    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 2014
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    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 operatiol catch and effort data of the Japanese tu 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.
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    CPUE standardization of blue marlin (Makaira mazara) caught by Taiwanese longline fishery in the Indian Ocean for 1995 to 2011 2013
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    This study provided a CPUE standardization of blue marlin (Makaira mazara) 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 alysis since blue marlin is caught by Taiwanese longline fleet as bycatch species and large amount of zero catches are recorded in the operatiol data sets. The results indicate that the influence of incorporating environmental effects on CPUE standardization is not significant for blue marlin in the Indian Ocean. The trends of CPUEs in Area 1 (MONS) and Area 3 (Coastal area) revealed substantial decline trends before early 1990s and increased until later 1990s, while the CPUE in Area 2 (ISSG) continuously increased before 1995s. The CPUEs slightly increased before 1998 and 2002 for Area 1 and Area 2 respectively, revealed decreasing patterns until 2008, and they sharply increase in recent years. However, the trend of CPUE in Area 3 obviously increased before 1999 but the continuously decreased thereafter. The area-aggregated CPUE generally reveals a trend for five phases: fluctuated before 1986, sharply decreased during 1986-1990 when the catch began increasing; increased gradually during during1991-1999; decrease gradually during 2000-2007; CPUE obviously increased in recent years.

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