| 英文摘要 |
Yellowfin tuna is one of the important catch species of Taiwan distant water tuna longline fishery in the Western and Central Pacific Ocean (WCPO). Taiwan, as well as Japan, are the only fishing countries in the area with long series of catch data. In this regard, estimating Taiwanese yellowfin tuna abundance index is an important task to facilitate the stock assessment of the resource. Since the target species of Taiwanese longline fishery has changed in the course of fishery development, target effect becomes an indispensible factor and needs to be properly addressed in the standardization procedure. This paper considered and analyzed several factors in the generalized linear model (GLM) for standardizing CPUE of yellowfin tuna. The result indicates that 5-degree grid factor should be considered in the GLM, and the standardization should be conducted separately by region, rather than combining all regions as one. It also demonstrated that target factor has substantial effect on the standardization quality, and?it is advisable to separate fisheries data by target or fishing pattern, before proceeding the standardization analyses. |
