太平洋東部赤道付近におけるメバチの漁況経年変化の原因について-III

Abstract

The authors have studied the relation between annual variation of hook rate (catch per 100 hooks) and that of age composition, and obtained following results: 1) It is considered that high hook rate was caused by appearance of dominant year classes. 2) The year classes in sub-areas NW, NM and SW, born in 1952 to 1953 are more inferior, and hook rate in these sub-areas from 1957 to 1958 when those year classes is 5 or 6-years are low. The year classes in sub-areas SM and SE, born in 1952 to 1953 are more dominant, and hook rates in those sub-areas from 1957 to 1958 are high. 3) Annual variation of hook rate almost agrees with annual variation of mean body weight.