A Midwater Trawl Net with Mouth Opening Canvas Devices for Stock Assessments.
A Midwater Trawl Net with Mouth Opening Canvas Devices for Stock Assessments.
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带有开口帆布装置的中层拖网，用于种群评估。
DOI：
10.2331/suisan.62.254
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发表时间：
1996
影响因子：
0.4
通讯作者：
T. Miura
中科院分区：
文献类型：
--
作者：
T. Yonezawa;Y. Fujimori;S. Shimizu;K. Nashimoto;T. Miura
这项工作的目的是开发中层拖网来调查鱼类种群。为了准确测量鱼类种群密度，需要保持恒定的网口张开度。为此，将帆布风筝附着在中层拖网上，而不是浮子和重物。附着在头绳和地绳上的帆布风筝的面积是从拖曳力和网的阻力的垂直分量之和之间的平衡得出的。在水槽中以二十分之一的比例进行模型试验，比较了风筝型网与浮子型网的静力特性。此外，在RV“Ushio-maru”上对全尺寸风筝型网进行了检查。风筝型模型在当前速度范围内比浮式网保持更恒定的形状和网口面积。按照规划，全尺寸风筝式网保持7米的恒定网口高度。根据这些结果，我们得出结论，建议使用风筝型网作为鱼类种群评估的更好的采样装置。
The purpose of this work is to develop a midwater trawl net to survey fish stock. A constant net mouth opening is necessary in order to measure fish stock densities accurately. For this purpose, canvas kites were attached to the midwater trawl net, instead of floats and weights.The area of canvas kites attached to the headrope and groundrope was derived from the equilibrium between the sum of vertical components of the towing force and the drag of the net. The model test were made with a scale of one-twentieth in a flume tank, in which the static characteristics of the kite-type net were compared with those of the float-type net. Further, a full-scale kite-type net was examined aboard the RV “Ushio-maru”.The kite-type model maintained a more constant form and net-mouth area than the float type net over a range of current speeds. The full-scale kite-type net maintained a constant net mouth height of 7meters, according to the plan. From these results, we conclude that the kite-type net is to be recommended for a better sampling device for fish stock assessments.