碩士 / 國立臺灣大學 / 海洋研究所 / 100 / Blue marlin is a highly migratory species mainly distributed in tropical and subtropical waters of the world. In the Atlantic, blue marlin is a by-catch of longline fisheries, mostly caught by Japanese and Taiwanese longliners. The catch from gillnet fishery of Ghana increased in recent years. Catch per unit effort (CPUE) is usually used as relative abundance index in stock assessments. However, catchability is affected by spatio-temporal distribution of fish population as well as the evolution of fishing gear. Consequently, CPUE should be standardized to represent as an abundance index. In this study, the generalized linear models (GLM) were applied to standardize CPUE data of blue marlin for the longline fisheries of Japan, Taiwan and Brazil, and gillnet fishery of Ghana. The factors considered in GLM include year, month, fishing area, and the interaction term between month and fishing area. The standardized CPUE generally showed a gradually declining trend. In addition to these four standardized CPUE series, we also collected standardized CPUE series from ICCAT for longline fisheries of USA and Venezuela, gillnet fishery of Venezuela, and recreational fishery of USA. The non-equilibrium surplus production model ASPIC was then applied to assess the stock status of the Atlantic blue marlin. Results showed that the maximum sustainable yield (MSY) was estimated at 2537 tons, and B2010/BMSY and F2009/FMSY were estimated at 0.745 and 1.508, respectively, indicating that the blue marlin stock is in an overfishing and overfished status. The results suggest that the total allowable catch (TAC) of blue marlin should be reduced to 2000 tons in order to recover the stock to near the level corresponding to MSY.
| Identifer | oai:union.ndltd.org:TW/100NTU05279003 |
| Date | January 2012 |
| Creators | Yi-Lin Tsai, 蔡易霖 |
| Contributors | Chi-Lu Sun, 孫志陸 |
| 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 |
Page generated in 0.0018 seconds