| 英文摘要 |
This study aimed to explore the distribution patterns of size and CPUE of south Pacific albacore stock caught by Taiwanese longline fishing fleet. Results indicated that longline vessels may shift their target on different species after 1997. The seasonal catch of albacore was opposite to the catch of tropical tunas after 1980 indicating that some vessels may actually also shift their target between two types of tuna during this period. Catch per unit and size data also showed that major fishing ground for Taiwanese albacore fleet was mainly in the mid-latitude (10-40NS), and that larger albacore was distributed mainly in the low latitude region while smaller individuals were more abundant in high latitude. Besides, mean weight of albacore in the spring and summer in south Pacific region was higher than those in the fall and winter. And, albacore CPUE during the fall and winter, the spawning season of albacore, in the north was much lower than those in the south while it was higher in the spring and summer. Both obvious differences may be used for future separation of catches data obtained from canning industry。Furthermore, size data recorded in current data set from the north Pacific region was much smaller than those in the south, and also different from back-calculated size from mean weight indicating a potential error in this data set. In addition, in order to have a representative CPUE trend for the stock, it was also suggested that some vessels target, or seasonal target on sharks and/or other species should be filtered out and excluded from the analyses. |
