@article{oai:ir.kagoshima-u.ac.jp:00002447,
 author = {辺見, 富雄},
 journal = {鹿児島大学水産学部紀要=Memoirs of Faculty of Fisheries Kagoshima University},
 month = {2016-10-27},
 note = {Some informations obtained by the author as the result of tuna-long-line fishing training
carried out near the Maratua Island in the Celebes Sea, with the training-ship Keiten-Maru (269
ton) of our Faculty shall be reported.
Up to this day a lot of studies have been done about the vertical tuna-long-line form, but
as to horizontal form few studies have been done, as the attentions have been paid chiefly to the
fixing of the letting-go-line and heaving-up-line positions and to the counting of the shift and the distance between the both ends of the long-line.
Accordingly the track of the horizontal tuna-long-line form was ascertained, by clearly
plotting, with the interval of half an hour, the ship-position, namely the long-line position.
Provided the technical conditions of the letting-go-line, the heaving-up-line, and seasonal
conditions remain the same, the author divided the horizontal forms into three kinds, A, B, and
C: Here kind A shows good catch (hooked rate of tuna 5.26%), kind B shows bad catch (hooked
rate of tuna 1.30%), C shows the one which belong neither of these two.
As to these two kinds, the difference of the form was investigated with the ascertainment
that concerning the shift of the line-end, the shifting distance is small, in case of A, showing the
shift of 0.68 mile per hour, in case of B, 1.97 mile.
Some difference can be seen in the figures and types of the line.
The relation between the line-shift and the fishing conditions was studied oceanographically,
with the result that in A kind eddies, convergence is to be observed, which prevent the fish from
swimming away in B kind, the tide current showing a fixed direction, the shift of the line is apt
to be accelerated., The observation of the horizontal "long-line form" led the author of the following conclusion:
1). Good catch can be expected when the long-line form shows A form, provided that
water temperature in 150 m. layer 21~23°C.
2). Bad catch is to be expected when it shows B form in this case the water temperature in 150 m. layer is 19°C.
3). when C form is got, this may be fixed to be belonging to A or B form on the
second operation.
As reported above, the ascertainment of the relation between the "horizontal tuna-long-line form" and the shifting of the line, enables us to foretell the catch on the spot, giving us much
benifit in establishing the fishing schedule here after., 1959~1962年の間のセレベス海,マラツア島近海漁場における,多数の縄位置をプロットして,水平的縄の形状並びに縄の流動の状態を観測し,これをA,B,Cと3種の型に大別し,この型と海況,漁況との関係を考察した。A型の場合は,漁場付近で暖水帯と冷水帯とが相接し,潮境を構成しているようであり,そのため縄の移動量が少なく,流動方向も区々で,彎曲,交叉が相当あり,鉛直温度分布より躍層が150~200mの間に存在し(150m層,水温平均21.3°C),釣針深度が躍層以浅の暖水中にあるものと思考され,その結果キハダの好漁をもたらしたものと考察される。また,B型は,漁場付近が冷水帯の流水中に存在し,そのため,縄の移動も大きく,定常方向に流され,彎曲,交叉が全然出現しないものと考える。また,水温,躍層もA型に比し浅く(70~150mの間),150m層の平均水温は18°Cであり,この場合においては,釣針もほぼその付近に存在し,このことが漁況不振の原因となっているように考察される。C型は,出現回数が少なく,持続性なく,1~2日でA,B型に変化するものである。以上のように,水平的縄なりは漁況と密接な関係を有し,その結果水平的縄なりの観察は現場において漁況を予察し,早期海況予報を可能ならしめ,操業計画並びにその後の航海計画樹立に大いに役立つものであると考察する。},
 pages = {93--103},
 title = {セレベス海におけるマグロ延縄の水平的形状と漁況とについて},
 volume = {13},
 year = {}
}