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魚群探知機に現われた記録解析の試み―3 : 鮪延繩の水中型状変化の力学的考察及び鈎深度のコントロールについて

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タイトル: 魚群探知機に現われた記録解析の試み―3 : 鮪延繩の水中型状変化の力学的考察及び鈎深度のコントロールについて
その他のタイトル: Analysis of Fish Finder Records―III.On a Dynamical Study of External Force on the Tuna Longline and Control of the Hook Depth
著者: 柴田, 恵司 / 矢田, 殖朗
著者(別表記) : Shibata, Keishi / Yada, Shigeaki
発行日: 1963年12月
出版者: 長崎大学水産学部
引用: 長崎大学水産学部研究報告, v.15, pp.49-58; 1963
抄録: Recently the quality of the fish finder has been much improved. By 14-kc-28kc detectors a single tuna has come to be recorded down to 300m. in depth, and 200-kc detectors can trace the underwater distribution of tuna longlines down to 150m. Therefore, the most ideal operating method of tuna longline fisheries, which is a kind of hook fisheries, is "to select places crowded with fish schools and to develop baited hooks." In order to investigate this problem, the authors performed an experiment, concerning the developing method of the tuna longline, at the Philippine Sea on July 3rd, 1963. The underwater distribution of the tuna longline could be detected by using a 200-kc fish detector. The results showed that the hook depth of a 250m mainline could be controlled down to only 140m. Again, the external force on the longline was calculated from the echogram, and the results showed, in regard to the face current, that the constant current was 330° in direction and 1 nautical mile/hr. in speed, and that the turblent current was unstable in direction and 0.2-0.5 nautical mile/hr. in speed. However, as bigger tunas were observed to be distributed densely at deeper layers than at the depth of 150m., the gear should be improved so as to catch fish distributed in those deeper layers. It seems that the only way to be taken for this purpose is to increase the mainline length.
URI: http://hdl.handle.net/10069/31620
ISSN: 05471427
資料タイプ: Departmental Bulletin Paper
原稿種類: publisher

引用URI : http://hdl.handle.net/10069/31620



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