碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 92 / Abstract
In this study, we use the 5x5 degree longlinning catch and effort data compiled by SPC to observe the distribution and migration characteristics of South Pacific albacore. Both gravity of fishing ground and vector of each grid and calculated by using 5 by 5 CPUEs of albacore, with which the displacement of distribution and migration routes are estimated. Meanwhile, the temperature of SST and subsurface layers collected from NOAA were also conducted vector computation accordingly to determine flow trend and its relationship with the result from gravity and vector analysis. The following are the conclusions of the study:
1. The zonal displacements of the gravity of albacore fishing grounds are mainly seasonal without inter-annual change. The higher latitude shows higher extent of seasonal displacement in zonal direction.
2. Meridianal displacements of the gravity show a southward trend during recent decades. The CPUE at higher latitude increase significantly since 1992 and at the mean time the temperature of the latitude turned high gradually, especially in waters west of 160°W.
3. The vectors computed by 3x3 CPUE cells show that the flowing trend of each grid. Vectors of the whole region show the migration direction are basically along with the South Pacific Gyre. The vectors in archipelagic waters (western Pacific), Tasman Sea, Eastern Australian and STCZ waters show relatively stronger seasonal variations, however they still follow the anticlockwise migration loop in the open ocean.
4. The 20-year albacore flow determined by average of the vectors (1980-2000), mainly point to the south, are consistence with the vector of warm water flow calculated by 3x3 temperature cells at layers of 200~300m.
The algorithm developed in this study for calculating vectors of each grids are proved useful in estimation of the flow trend of albacore CPUE. However, the 5 degree cell size and temporal interval of 1 month are not fine enough to get detail migration information required in fishing operation level. The migration picture obtained in this study only represents albacore at size (age) of longliner’s target, mainly mature or pre-mature. More data from surface fisheries need to be insert before we learn equivalent understanding for those albacore at younger life stage.
Key words： Albacore, South Pacific Ocean, Subtropical Convergence Zone
| Identifer | oai:union.ndltd.org:TW/092NTOU5451025 |
| Date | January 2004 |
| Creators | Chiu-Hsia Cheng, 鄭秋霞 |
| Contributors | 呂學榮 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 68 |
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