| Project/Area Number |
09660198
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
NAKAMURA Yoshihiko Fisheries, Tokyo University of Fisheries, Professor, 水産学部, 教授 (10017072)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASU Yasusuke Fisheries, Tokyo University of Fisheries, Professor, 水産学部, 教授 (30017066)
SAKURAMOTO Kazumi Fisheries, Tokyo University of Fisheries, Assistant Professor, 水産学部, 助教授 (60111689)
YADA Sadami Fisheries, Tokyo University of Fisheries, Professor, 水産学部, 教授 (60230249)
KURITA Yoshihiro Fisheries, Tokyo University of Fisheries, Assistant Professor, 水産学部, 助教授 (80106757)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | SIZE SELECTION / SORT-X / GRID SPACING / SELECTIVITY / TRAWL FISHING / FLAT FISH / TAC / ソ-トX |
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| Research Abstract |
In test tank (100 × 5 × 1.5m) the model experiments of Sort-X were carried out with different towing speed using model trawl net. Fluid resistance of Sort-X was 3% to 4% of all net. In the experiment using a one fifth scale model it was observed that No.3 grid frame was sticked fast to bottom net. To keep them apart the No.3 grid canvas was replaced by minnow net. As it required time to replace No.1 and 2 grids by different bar spacing grids, new technique of bar spacing control was developed. From Aug.26 to Sep. 1, 1998 the selectivity experiment of the Sort-X built as a trial was carried out in the Okhotsk by using T/S Shinyomaru. In the experiment two types of Sort-X were used ; one was fixed bar spacing and another was trial Sort-X in which bar spacing was changed from 2.5cm to 4.5cm easily. To save fish escaping from grid spacing the cover nets were set on No.1 and 2 grids, respectively. The numbers of flat fish caught in a cod end and in two cover nets were counted, respectively ; at the same time fish length, height and weight were measured. The catch of cover nets was 10% to 25% of all catch ; this deviation was considered to be the effect of trial Sort-X grid space. The master curve of grid selectivity in the trial Sort-X was computed in which 50% selective fish height wa 3.2cm, 4.0cm and 4.8cm at grid spacing of 4cm, 5cm and 6cm, respectively. The weight of trial Sort-X was so heavy as twice of usual one that it was necessary to add many floats and shape of net was deformed.
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