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スキャンニングソナーによる定置網漁場の魚群行動調査 (1) Studies on Fish Behavior with Scanning Sonar around Set Nets·I 小八幡漁場，江ノ浦漁場に於ける魚群行動 Observing Fish Behavior in Koyawata and Enoura Fishing Grounds in Sagami Bay Tawara, Yozo 田原, 陽三 タワラ, ヨウゾウ Tawara 田原 タワラ Yozo 陽三 ヨウゾウ Inoue, Yoshihiro 井上, 喜洋 イノウエ, ヨシヒロ Inoue 井上 イノウエ Yoshihiro 喜洋 ヨシヒロ Mori, Keishiro 森, 敬四郎 モリ, ケイシロウ Mori 森 モリ Keishiro 敬四郎 ケイシロウ metadata only access The authors made a trial of scanning sonar to observe fish behavior swimming toward a set net in may, 1981. Although there still remain various questions, the results obtained proved it to be one of the most optimum methods at this stage capable of grasping fish behavior around the set net in a normal condition (previous report). The investigation of fish behavior with this method was then repeatedly conducted day and night around the fishing grounds of Koyawata and Enoura in the Sagami Bay between September 25 and October 16, 1981. The reserch vessel "Takamaru" in which the scanning sonar is installed was anchored in front of the set net and mainly observed fish behavior in front of the leading net (Fig. 2 and 3). During the period of the investigation, a school of fish coming around the set net were too small to sufficiently grasp its behavior, however, the investigation enabled us to gain a general idea. Photo 1 shows fish images that appeared on the scanning sonar. The fish behavior illustrated in Figs. 4 and 6 are thus obtainable from the photographs. (1) The fish behavior has a close relationship with geographical conditions (isobath of the sea bottom. (2) The fish school coming into the sea area shallower than 40 m is high in ratio of entering the net. (3) The leading net was observed to be effective for interception and guidance of fish (Fig. 6-1~6-6). (4) The fish school that approaches to a level of more than 60 m in depth to the net is low in ratio of entering the net (Fig. 6-8~6-14). (5) The fish school seems to stay around the net of the play ground and the anchor ropes of the main buoys, and such a fish school tends to move toward the front of the leading net to enter the body net (Fig. 7). (6) The fish school, while moving will complicatedly vary in its form (Photo. 1). As mentioned above, we could acqire foundamentally valuable data for improving net construction technics and establishment of characteristic conditions for setting the set net, not to mention the importance of collecting fundamental data. 水産工学研究所 National Research Institute of Fisheries Engineering 1983-03 jpn departmental bulletin paper https://fra.repo.nii.ac.jp/records/2007744 nrife_k_4_197 https://agriknowledge.affrc.go.jp/RN/2010273691 日本農学文献記事索引(agriknowledge) AN00332937 0388-9718 水産工学研究所報告 Bulletin of National Research Institute of Fisheries Engineering 4 24 197 220