- 著者
-
"肥後 伸夫
上水樽 豊己"
- 出版者
- 鹿児島大学
- 雑誌
- 鹿児島大学水産学部紀要=Memoirs of Faculty of Fisheries Kagoshima University (ISSN:0453087X)
- 巻号頁・発行日
- vol.28, pp.119-129,
"Using, as the experimental apparatus, a trawl net the full body of which was made to be lifted at a certain distance from the sea bottom, some experiments were carried out on its limit of catchability.In this experiment the apparatus was made of the following gears: firstly, a lot of long chains were attached vertically to the floats, and secondly, these were made to be set to the ground rope and to the lower belly of the trawl net.The results obtained are as in the following:1) The size of the trawl net is as follows; namely, the length of the head rope is 29.8 m, the full length of the net is 26.0 m. To this is attached a beam which is as long as 18.0 m. This trawl net was hauled at the speed from 0.5 knot to 3.0 knot. 2) The catchable towing speed was ascertained to be within the range from 1.5 knot to 2.0 knot. The vertical distance of the off bottom trawl net from the sea bottom was counted to be 40~70 cm.3) The main kinds of the caught fish were as follows: - Taius tumifrons; Nephrops thomsoni: Octopus thomsoni; Navodon modestus; while Seurus undosquamis; Chelidonichthys kumu, and Muraenesox cinereus were uncatchable; on the other hand stones, shells, starfish were left untouched, too.4) The vertical distances of the net detached from the water bottom wereascertained to be almost equal both in case of the measuring on the spot and in that of the experimental model measuring.""底曳網全体を海底から僅かに離底させて曳網する実験を試みた。底曳網は浮子綱長 29.8m, 網の全長 26.0m の規模のもので, 18m のビームに装着し, 0.5 ノットから 3.0 ノットまで曳網した。離底の装置は浮子に長いチェンを垂下したものを数多く沈子綱と底曳網の下網に取りつけたものである。結果は次の通りである。1) 漁獲可能の曳網速力は 1.5 ノットから 2.0 ノットまでである。その時の離底の高さは, 40~70cm である。2) 入網魚の主なものはキダイ,エビ,タコ,ウマズラハギでエソ,ホウボウ,ハモ,アナゴは入網しない。3) 同時に曳網実験をおこなったトロール網,小型底曳網に比較して,石,貝,ヒトデ等の混獲物はほとんどみられない。4) 計器による実測と模型実験による網の離底の高さは略一致する。また網口高さは,低速側で模型実験値が若干高くなるが, 25 ノット以上になると略一致する。"