| The catch per unit of effort (CPUE) of bigeye caught by the Japanese longline fishery in the Indian Ocean was standardized up to 1997 using general linear model (GLM) analysis. Standardized CPUE in the tropical area, which was relatively stable, ranged from 6 to 8 fish per 1,000 hooks in 1979-1987 and decreased continuously to about 4 in 1997. In contrast, CPUE in the southern area did not show the stable trend of the tropical areas, especially after 1990. This unstable CPUE pattern in the southern area in recent years seems to be derived mainly from the shift of targeting in longline operations. If the trend derived from analysis for 1952-1976 is included, current CPUE is estimated to be about 33 % of that in 1954. |
