2 0 0 0 OA オホーツク海北部における夏季のニシンの分布および生物学の特徴について
- 著者
- 高橋 豊美 上野 元一 島崎 健二
- 出版者
- 公益社団法人 日本水産学会
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.39, no.7, pp.759-764, 1973-07-25 (Released:2008-02-29)
- 参考文献数
- 11
Though many biological studies have been made on the commercial-sized herring, Clupea harengus pallasi, in the northern part of the Okhotsk Sea in summer, knowledge on the dis-tribution and biological characteristics of the juvenile in the same period is inadequate even today. The authors studied informations obtained from the measurements of about 2400 samples. The samples were obtained by surface gill nets, varying in mesh size from 30mm to 82mm, used for capturing juvenile salmon, and the samplings were conducted on the research vessel “Oyashio Maru” in the northern part of the Okhotsk Sea from August 17 to September 3, 1971. The results obtained are summarized as follows: 1) The shoals, composed of middle and large-sized fish (20-33cm) were found in the area off the Koni Peninsula, the small-sized fish (12-15cm) in the area off the Okhotsk, and the medium-sized fish (18-26cm) in the area off the Ayan. The area, where each shoal appears, seems to vary yearly. 2) The fish of 2-3 age were observed in comparative warm waters (13-14°C) in 1971, 12-13°C in 1970 (Unpublished data). 3) Samples of the 4 age, caught in the area off the Ayan, were smaller in their average fork length, and heavier in the ratio of body weight to fork length, and higher in the mean maturity index {gonad weight×102/(body weight-gonad weight)} than those from the area off the Koni Peninsula. There is a possibility that the fish in the area off the Ayan may not belong to the Okhotsk population.
1 0 0 0 OA スケトウダラ稚仔の沿岸水域での生活
- 著者
- 前田 辰昭 高橋 豊美 上野 元一
- 出版者
- 日本水産學會
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.47, no.6, pp.741-746, 1981
- 被引用文献数
- 2 7 7
Once a month from February 1974 to February 1975, adult Alaska pollack <i>Theragra chalcogramma</i> (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 fo the eggs. As a result, the annual life cycle of the adult Alaska pollack from February 1974 to February 1975 was diveided into four periods as follows.<br> 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.<br> 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.<br> 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 beginnign 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.