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Title: 西部印度洋に於ける鮪類の体長組成に就て
Other Titles: Size compositoin of the Albacore, Big-eyed Tuna and Yellowfin Tuna caught in the West Indian Ocean.
Authors: 古賀, 重行
Authors (alternative): Koga, Sigeyuki
Issue Date: 28-Feb-1958
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.6, pp.92-96; 1958
Abstract: The sample of Tunas treated in this report were obtained from the catches of longline-fishing vessel of Nippon Suisan CO. in the West Indian Ocean during three monthes from December 1955 to February 1956. (1) It is recognized clearly that there is a remarkable difference of size composition of Yellowfin Tuna by the season and sex. (2) The size of male Tuna is bigger than that of female in the West Indian Ocean Area. (3) The variety of folk length frequency of Yellowfin Tuna, Big-eyed Tuna, Albacore are each 100cm, 90cm, and 70cm respectively. (4) In the school of big size Tunas, the percentage of male is bigger than that of female. Especially, in the Big-eyed Tuna, that tendency is most remarkable. But in the Albacore, the rate of their percentage is quite contrary. (5) On the same latitude, the big size Tuna is more hooked in the West Indian Ocean than the Pacific. (6) In the Indian Ocean, the folk length of Big-eyed Tuna seemed to become smaller gradually to east. (7) The Hooked-rate of Yellowfin Tuna in 1957 is less than that in 1956. As the results it is presumed that the West Indian Ocean is the best among the fishing grounds of Tuna. / この生駒丸操業期を通じて西部印度洋海区のマグロを体長の面より考察してその特性を挙げて見るとマグロは季節に依て体長に変化あり,キハダは季節の移行と共に大きな体長群の出現が増している.性に依る魚体差が判然としていて夫々の性に依る平均体長は雄の方が雌より大である.体長分布範囲はキハダ100cm,メバチ90cmビンチョウ70cmを示している.就中ビンチヨウは狭い特徴を示し,俗に言う粒が揃つていて全部大型ビンチョウであつた.キハダ,メバチに於ては雄は雌より大型体長群の占める割合が多かつた.特にメバチは顕著であつた.反対にビンチョウに於ては雌の方が大型体長群の占める割合が多かつた.同じ緯度と雖も西部度洋海区のは太平洋海区の鮪に比較して大型体長群の出現が大であつた.印度洋ではメバチは東移する程型が小さくなつている.キハダは中部,西部,東部の順序に小さくなつている.キハダはその釣獲率に於て1957年は1956年より顕著な減少を示している.以上の結果からして西部印度洋海区はキハダを主対象として操業する限り中部,東部印度洋海区,太平洋の各港区よりも型が大きく旦,増加している点と,釣獲率が依然として高率であることから考察してもこの西部印度洋海区は尚好漁場たるの価値を失うものではない.
URI: http://hdl.handle.net/10069/31931
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第6号

Citable URI : http://hdl.handle.net/10069/31931

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