碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 104 / Dolphinfish (Coryphaena hippurus) is a highly migratory species and distributes wildly in tropical and subtropical waters of the three oceans of the world. The catches of dolphinfish are caught in the waters around of Taiwan but are the most productive in the eastern waters. Therefore, dolphinfish is an important commercial species for offshore and costal fisheries in the eastern waters. To evaluate the stock status and fishing exploitation of dolphinfish in the eastern waters of Taiwan, this study analyzed the fishery and stock indicators based on the catches of daily auction data from 1999 to 2014 and length-frequency data from 2003 to 2014 obtained from Shingkung fish market in Taitung County. In addition, the length-based mortality model was adopted to explore the interaction between fishing mortality and body size of catches. Based on the monthly trends in catches and body length, two fishing seasons occurred for dolphinfish in the waters of Taiwan and the mean length of catches were obviously different in two fishing seasons. The mean length caught in the first fishing season (June and July) is larger than that caught in the second fishing season (November and December). Based on the analyses by vessel types, the mean length of catches caught by crafts is larger than that of rafts. The results of indicators related to length distributions indicated that the caches of dolphinfish in the eastern waters of Taiwan tend to be small in recent years, especially for females. In addition, body size of catches is also influenced by fishing mortality. The mean length of catches would decrease when fishing mortality increased. The results of this study indicated that fishing exploitation might have led to the decreases in the body size in recent years. Therefore, the influence of fishing exploitation on the stock status should be further considered to moderately exploit dolphinfish in the eastern waters of Taiwan.
| Identifer | oai:union.ndltd.org:TW/104NTOU5451035 |
| Date | January 2016 |
| Creators | Yang, Chia-Chen, 楊家榛 |
| Contributors | Wang, Sheng-Ping, Chiang, Wei-Chuan, 王勝平, 江偉全 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 58 |
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