噴火湾周辺海域におけるスケトウダラ成魚群の生活年周期

• Published in: NIPPON SUISAN GAKKAISHI
• Main Authors: 前田, 辰昭, 高橋, 豊美, 上野, 元一
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 日本水産学会
• Subjects: 663; Theragra chalcogramma; Alaska
• Online Access: http://hdl.handle.net/2115/38655; https://doi.org/10.2331/suisan.47.741

Once a month from February 1974 to February 1975, adult Alaska pollack Theragra chalcogramma (PALLAS) were caught by bottom gill nets at four definite stations in the adjacent waters of the Funka Bay, Hokkaido. The authors examined several biological factors of the Alaska pollack, density of the fish shoal, and distribution of the eggs. As a result, the annual life cycle of the adult Alaska pollack from February 1974 to February 1975 was divided into four periods as follows. 1) Spawning period, judging from the value of gonad index and the maturation stage of the adult Alaska pollack, was from December to March, and the peak in the period was from December to February. 2) Feeding period, judging from the value of feeding index, percentage of empty stomach and the value of liver index, was from May to October, and the peak was during July and August. 3) As the transitional periods, the terms from the end of spawning period to the beginning of feeding period and from the end of feeding period to the beginning of spawning period were assigned. The former was from the last of March to the last of April, and the latter was from the last of October to the last of November. 1974年2月から1975年2月に至る期間に毎月1回底刺網を用いてスケトウダラを漁獲し，生物学的測定をした。それらのうち，成魚について生殖巣指数，生殖巣熟度組成，空胃率，摂餌指数，胃内容物および肝臓指数を検討し，魚群の分布密度やスケトウダラ卵の分布密度を含めて成魚群の生活期を考察した。1.産卵期は12月から2月を中心とした12～3月である2.索餌期は7月から8月を中心とした5～10月である。3.産卵期と索餌期，索餌期と産卵期の間には分布回遊を含めた生態的に異なった魚群が混在している。したがって，3月末から4月末を産卵期から索餌期への移行期，10月末から11月末を索餌期から産卵期への移行期と区分した。