鮪はえなわの漂移から得た掃海区域について(日本航海学会第32回講演会)

概要

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Long lining is the best method for catching tuna at a depth of 80 to 180m. Construction of the fishing gear is shown in fig.1. 2. The principal items are main lines (cotton or nylon yarn), branch lines (cotton or nylon yarn) and hooks. Auxiliary tools are buoy lines, buoys (glass balls), bamboo rods. A set of unit line is 200 to 400m. long, with branch lines about 10 to 20m. long. The depth of hooks is adjusted by the buoy line to meet the swimming shoals. About 4a.m. we start the work. The unit lines are joined, hooks are baited with frozen sauries, and sets are cast into the sea from her stern with the speed about 8 kts. The work is continued till about 8a.m. After the work was finished, the boat drift there about 4 hours. About 11a.m., we commenced to haul the lines toward the end, and continue this work 12 hours. About 11p.m. all finished the work. During the work long lines drift off by current. When the fishing gear drift freely without foul, we can consider that the depth of the sea is more deeper than the depth of the fishing gear.
社団法人日本航海学会の論文
1965-07-25