碩士 / 國立高雄海洋科技大學 / 漁業生產與管理研究所 / 104 / The blue shark catch and effort data from observers’ records of the Taiwanese large longline fishing vessels operating in the Indian Ocean from 2004-2013 were analyzed. Based on the effort distribution and fishing grounds of the target species, four areas, namely, A (north of 10°S, east to 70°E), B (north of 10°S, 70°E-120°E), C (south of 10°S, 20°E-60°), D (south of 10°S, 60°E-120°E) were categorized. To cope with the large percentage of zero shark catch, the catch per unit effort (CPUE) of blue shark, as the number of fish caught per 1,000 hooks, was standardized using a two-step delta-lognormal model that treats the proportion of positive sets and the CPUE of positive catches separately. Each model includes the main variables year, quarter, longitude, latitude,area, hooks per basket (HPB), and all two-way interactions between quarter, area and HPB. Standardized indices with 95% bootstrapping confidence intervals were reported. In India Ocean, the high shark bycatch number was found in major fishing ground for the bigeye tuna fleet, the highest proportion was blue shark. The standardized CPUE showed a stable trend for blue sharks from 2004 to 2008 and increased steadily thereafter with peaks in 2013. The results obtained in this study can be improved if longer time series observers' data are available.
| Identifer | oai:union.ndltd.org:TW/104NKIM0451005 |
| Date | January 2016 |
| Creators | SHAO, WAN-CHIEH, 邵琬絜 |
| Contributors | TSAI, WEN-PEI, 蔡文沛 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 65 |
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