太平洋東部赤道付近におけるメバチの釣獲率経年変化

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The following results were obtained from an investigation on relation of annual variation of catch-rates of big-eyed tuna in the eastern Pacific tropical water area, between south-and-northwise, east-and-westwise and summer season-and-winter season: 1) All the catch-rates shown in division by lat. 10° and long. 5° were high in 1955 and in 1959 through 1961 in the northern part than the equator. In waters southern than the equator, the catch-rates kept leveling in 1958 through 1960 and declined in 1960 through 1962 in sub-area from long. 100°W to 115°W, kept leveling in 1957 through 1961 and declined in 1961 through 1962 in sub-area from long. 115°W to 135°W and declined in 1957 through 1959, increased in 1959 through 1961 and declined again in 1961 through 1962 in sub-area from 135°W to 150°W (Fig. 3). 2) Annual variation of catch-rate of big-eyed tuna in divisions of lat. 0°-5° in each sub-area looks almost same with the annual variation of catch-rate of the fish in divisions of lat. 5°-10° in each sub-area (Fig. 4). 3) Annual variation of catch-rate of big-eyed tuna in summer looks almost same with the annual variation of catch-rate of the fish in winter (Fig. 5). 4) Higher catch-rate of big-eyed tuna in sub-area D happened in 1958 through 1960, that of the fish in sub-area A happened in 1959 through 1961, that of the fish in sub-area B hap-pened in 1960 through 1962 (Fig. 6).
社団法人日本水産学会の論文