房総海域におけるカタクチイワシの漁業生物学的研究-1-大型成魚の成熟,集合および卵の分布について

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概要

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• The waters off the Boso Peninsula are one of the most important fishing grounds for the adult Japanese anchovy, Engraulis japonica (HOUTTUYN). They occur in the area during winter and spring, and are caught chiefly by two-boat purse seiners. The adult stock comprises two age groups, small sized adults of about 1-year-old and the large-sized ones of baout 2-yea-old. The author examined maturation and aggregation of the large-sized adults, and distribution of the eggs taken off the Peninsula during winter through summer in 1965 and 1966. The results are summarized as follows. 1) The large-sized adult stock was much larger in 1965 than 1966. 2) The stock in both years comprised three subgroups. The first subgroup was exploited only in December. The latter two subgroups appeared in December through April, and in April through July, respectively. The last subgroup remarkably dominated in the 1965-66 fishing season. 3) The fishing season was diveded into three phases; premature (up to eatly March), maturing (middle March through early May), and ripening (middle May through late July). As the diameter of ova of the largest group reached almost their maximum size in the maturing and ripening phases, spawning of these anchovy was considered to be extended from middle March through late July. 4) In 1965-66 season, the large-sized adults of pre-mature phase first appeared in the waters off Zyoban and the Boso Peninsula, and gradually moved southward, reaching as far as the Suruga Bay. In maturing phase, density of the fish decreased and the centre of distribution located in the Suruga Bay. In ripening phase, the fish moved northward, and the centre of distribution appeared again in the waters around the Boso Peninsula. 5) Along the Pacific coast of Honsy ?? first the anchovy eggs occurred in the waters around the Boso Peninsula in winter, and then the distribution area extended westward, corresponding to the shift of the distribution of large-sized adults. This fact indicates that the large-sized adults are main producer of the eggs found in the waters around the Boso Peninsula.

• 社団法人 日本水産学会の論文

著者

• 平本 紀久雄

  千葉県水産試験場

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• 房総海域におけるカタクチイワシの漁業生物学的研究-1-大型成魚の成熟,集合および卵の分布について

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