微離底曳網の実用化に関する研究
The off bottom trawl net commonly called Sea slater Net or chain net is a newly deviced fishing net supplied with a fishing line to the lower side of which are attached a series of bothbouys and hanging chains; when this is put under operation this fishing line is to be drawn, detouched more or less...
| Main Authors: | , , , |
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| Format: | Report |
| Language: | Japanese |
| Published: |
鹿児島大学
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10232/13290 https://ir.kagoshima-u.ac.jp/?action=repository_uri&item_id=10805 https://ir.kagoshima-u.ac.jp/?action=repository_action_common_download&item_id=10805&item_no=1&attribute_id=16&file_no=1 |
| Summary: | The off bottom trawl net commonly called Sea slater Net or chain net is a newly deviced fishing net supplied with a fishing line to the lower side of which are attached a series of bothbouys and hanging chains; when this is put under operation this fishing line is to be drawn, detouched more or less off the sea bottom.The possibility of its practicality has been proved by the repeated towing tests carried outon board the training ship.Basing on the assessment of the results obtained from (1) the 4 times drawing testsperformed by the 2 training ship on the East China Sea in 1982 (2) the 25 times fishering testscarried out by the trawler No.37 DAIKICHI MARU on the Bering Sea (3) the model testscarried out in the water tank the following concluusions were fixed concering its practicality.(1) Fishing Capacity :The value of the Catch Per Unit Effort of the chain net was equivalent to 47~82% of that of the regular net. Even put under a statical assessment, in the fish composition of the caughtfish an obvious distinction was noted between the chain net and the regular net; theusefulness of the chain net as a Fish species Selecting apparatus was ascertained. The amount of dergs and drains drawn into the net was noted to be quite negligible.(2) Gearing Capacity :In the both nets, almost no difference was noted between the height of net mouth.Concering the distance between the wing tips, that of the chain net was somewhat lager thanthat of regular net. The net resistance of the chain net was 15~30% less than that ofthe regular net.In the case when fishing was effective, the off bottom height of the chain net was 20~40cm in the Bering Sea, and it was 10~15cm in the East China Sea. The proper shape of thechain which was to be fixed in accordance with its resistance against the flowing water, was sought out theoritically; the diameter of the most proper chain was assessed to be 16mm.The slower was the towing speed, the longer the vertical past of the submerged hangingchain, which prevented fish school from running away : ... |
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