| 英文摘要 |
This study aimed to explore the distribution patterns of size and catch, as well as the standardization of CPUE index of south Pacific albacore stock caught by Taiwanese longline fishing fleet. A cluster analyses in conjunction with multiple dimensional scaling method and representative species analyses appear to be an effective method for identify different targeting practices of the fleet in the region. The separated norminal CPUE series which targeting on albacore tuna was different from a mixed data analysis, and showed that CPUE after 1999 was stable or even slightly increased instead of a sharply decrease。An estimated fishing effort of about 30% targeting on albacore, and 70% on bigeye seems maintained for this fleet since 2003. In addition, age composition of the stock, which estimated based on the mean weight-converted length indicated that the fleet mainly target on ages 7-10 of the stock. And, a standardization of the CPUE index for the stock also showed that the target effect was the most important factor in the model. And, catch ratio of the 5 species including albacore, bigeye, yellowfin, sharks and other fishes can be used as an criteria for identification of albacore targeting vessels, while bigeye, yellowfin, swordfish, blue marline, sharks and other fishes can be used for identify bigeye targeting vessels. It appears that both the standardization practice and the cluster analyses can be effective tools used for accounting the targeting effect of the CPUE series, and both results also showed a stable or even an increasing trend, instead of a continue decrease of the series in recent years. |