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西南太平洋における鮪類とカジキ類の漁況


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Title: 西南太平洋における鮪類とカジキ類の漁況
Other Titles: Fishing Condition of Tunas and Marlins in the Western South Pacific Ocean
Authors: 古賀, 重行
Authors (alternative): Koga, Sigeyuki
Issue Date: 30-Nov-1959
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.8, pp.57-79; 1959
Abstract: Basing on the data gathered by Koyo tuna-fishing fleet and the 11 Asahi catcher boat in the Fiji area during three months from September to November 1958, the following results are presumed as to the distribution of the tuna and the marlin. (1) In the Western South Pacific Ocean, especially in the Fiji area, hooked-rate was the most excellent in this area for the albacore and the striped marlin and moreover it differs clearly by latitude. In the seas of 170゚ E. to 170゚ W. between 20゚ S. to 30゚ S. Lat., the hooked-rate of the yellowfin tuna and the striped marlin showed the tendency to decrease according to the fishing ground proceed to southward, but, on the contrary, in the case of albacore, this rate was high. However, especially, in the southern region of 30゚ S. Lat., the hooked-rate of the albacore was lower than those in north of 30゚ S. Lat.. (2) In regard to the hooked-rate of tunas, it increased according to fall on month, but in the case of marlin this tendency was contrary. (3) The following characters are shown in regard to the size composition in the Fiji area. 1 Albacore…………In the Easterly fishing ground, according to proceed on southward, larger fishes-more than 95 cm in length-are decreased and the small fishes-less than 90 cm in length-are increased. 2 Yellowfin tuna………………In the Easterly fishing ground, according to proceed on southward, larger fishes-more than 130 cm in length-are increased and the small fishes-less than 100 cm in length-are decreased. 3 Striped marlin…………………In the Easterly fishing ground, according to proceed on southward, larger fishes-more than 200 cm in length-are increased remarkably. But in the Westerly fishing ground, this phenomenon was contrary and the body-length composition are considerably smaller than those of Easterly fishing ground. (4) The catcher of the albacore in the seas of 10゚ S. to Equator and the seas of 20゚ S. to 30゚ S. Lat. was composed of middle size and in the seas of 15゚ S. to 20゚ S. Lat., the fish groups are composed of relatively larger size. In the southern region on 30゚ S. Lat., and the seas of 10゚ S. to 15゚ S. Lat., the fish group are composed of smaller size. The catcher of the bigeye tuna was consist of middle size in the seas of 15゚ S. to Equator and the southern region of 30゚ S. Lat... In the seas of 15゚ S. to 30゚ S. Lat., the fish group are composed of larger size. The catcher of the yellowfin tuna in the seas of 15゚ S. to Equator was composed of middle size, and in the seas of 15゚ S. to 30゚ S. Lat., and the southern region of 30゚ S. Lat., they are composed of larger size. The catcher of the striped marlin in the areas between 10゚ S. to Equator the principal size were 160~170 cm in length. In the areas between 20゚ S. to 30゚ S. Lat., the principal size were 200~210 cm in length. (5) In regard to the tuna and the marlin, as the author reported before that difference in size of male and female was quite evident and this tendency was also recognized in the Fiji area. The size of male tuna was bigger than that of female, but in the striped marlin was quite contrary. (6) The fishing condition for the tuna in the Fiji area of this year, the hooked-rate was high and larger individuals were dominant than those of last year. From the above facts, the increase of the hooked-rate are supposed to be caused by increase of the large sized fish groups. (7) The author recognized that the rate of living tuna after hooked in this area was higher than that of the Atlantic Ocean. (8) Gvamus sp. and Pennella sp are hitherto be reported from the whale in the Antarctic Ocean as the External Parasite, and the both species were seen on the surface of the body of the striped marlin. / 広洋船団操業を通じて西南太平洋における鮪,梶木類の漁況を検討した結果次のような傾向が認められた。1. フィジー海域の釣獲率に見られる現象 (1) 漁場形成に重要なweightをもつビンナガは高緯度に向うに従って釣獲率は上昇するのに対し,キハダ,マカジキは逆に低下する傾向を示した。但し,30゚S以南になるとビンナガの釣獲率は低下する。本海域における平均釣獲率の変化はビンナガと同様な傾向を示す。(2) 1958年9~11月間において釣獲率は月を追うに従って鮪類は上昇し,逆に梶木類は低下する。2. フイジー海域の体長組成に見られる現象 (1) ビンナガ…………東経漁場において95cm以上の大型群の割合が南緯する程減少し,90cm以下の小型群の割合が増加する。(2) キハダ…………東経漁場において130cm以上の大型群の割合が南緯する程増加し,100cm以下の小型群の割合が減少する。(3) マカジキ…………東経漁場において南緯する程200cm以上の大型群の割合が増加する。西経漁場においては逆の傾向を示し,東経漁場に比べて比較的小型の群が多い傾向を示す。3. 緯度による魚体差 (1) ビンナガ 0゚~10゚S…………90cm~93cmの中型群が主群を形成す。10゚~15゚S…………小型群が主群を形成す。15゚~20゚S…………95cm以上の大型群が主群を形成す。20゚~30゚S…………中型群が主群を形成す。30゚S以南…………小型群が主群を形成す。(2) キハダ 0゚~15゚S…………100cm~130cmの中型群が主群を形成す。15゚~30゚S…………中型群が顕著に減少し,大型群の割合が増加して主群を形成す。30゚S以南…………大型群が主群であるが中型群が若干増加する傾向が見られた。(3) メバチ 0゚~15゚S…………100cm~130cmの中型群が主群を形成す。15゚~30゚S…………大型群が主群を形成す。30゚S以南…………中型群が主群を形成し,0゚~15゚海区よりも組成において優勢を示す。(4) マカジキ 0゚~20゚S…………160~170cmにmodeをもつ魚群が主群を形成す。20゚~30゚S…………200~210cmにmodeをもつ魚群が主群を形成す。4. 鮪類の性による魚体差は明瞭で雄は雌より大きく且つ,大型のものの割合が多い。マカジキは鮪類と逆の傾向を示し尚,雌は雄より顕著に大型のものの割合が多い。5. 1958年のフイジー海域の鮪類の漁況については前年度より釣獲率が高く大きい型のものの割合が多い。従ってフイジー海域において見る釣獲率の増大は大型魚群の増加を伴うものである事が考えられる。6. 鮪類の生死率についてブイジー海域の鮪類の生率は大西洋に比べて高い傾向が認められた。7. 南氷洋の鯨に見られるCyamus sp.とPennella sP.の外部寄生虫をマカジキの体表面に多数見受けられた。
URI: http://hdl.handle.net/10069/31817
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第8号

Citable URI : http://hdl.handle.net/10069/31817

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