計測による巾着網の研究-I : 豊後水道で操業されるイワシ巾着網の形状

概要

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Upon the fishing efficiency of the sardine purse seine operating by night in Bungo Channel, with the gathering lamp, the depth of the net foot has an important influence. On the gear shown in Fig. 1, the sinking depth of the net foot was measured with a self depth meter and some sounding chemical tubes, and moreover a model experiment was carried out in order to observe the transformation of the net. The results obtained are as follows; (1) The sinking depth of the net foot is as shown in Fig. 2 and Fig. 3. The depth of the middle part of the net foot was larger than the calculated net depth, but each wing of the net foot did not spread enough to reach the calculated net depth. The maximum sinking velocity (at the middle part of the net foot) was 16.5m/min. (2) The transformations of the net are as shown in Fig. 5. And on the sinking depth of the net foot, there was such difference between the full scale net and the model net as shown in Fig. 4. (3) The fishing efficiency of this gear to the depth of fish school is as shown in Fig. 6. The deeper a fish school is, the more the efficiency decreases when the net foot does not reach the sea bottom.
公益社団法人日本水産学会の論文