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西部印度洋に於けるマグロ類の胃内容物に就て


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Title: 西部印度洋に於けるマグロ類の胃内容物に就て
Other Titles: On the Stomach Contents of Tuna 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.85-91; 1958
Abstract: Examining the stomach contents of Tuna obtained in the West Indian Ocean during three monthes from December 1955 to February 1956, the following results were obtained; 1) The species of fishes obtained in the stomach were enumerated about 30. (c.f. Table 3-4) Especially, Plagyodontidaed, Polyipnus, Sphyraenidae, Juvenile Skipjack, Decapoda (Crustacea) and Decapoda (Cephalopoda) seems to be important as the food of Tuna in any other sea-areas. 2) These results were almost the same which were researched previously in the South Pacific Ocean and the adjacent seas of Bonin Islands. 3) Quantites of foods of Tuna in the West Indian Ocean were more rich than that of other sea-areas. 4) Compositions of food in each species of Tuna (yellowfin tuna, bigeyed tuna and albacore), ities were not so different to each others. 5) Quantites of stomach contents of yellowfin tuna, big-eyed tuna and albacore increased in accordance with season progress, but, on the contrary, in the case of big-eyed tuna this tendency decreased. 6) In the South Pacific Ocean, the stomachs of tuna were almost empty, but in the West Indian Ocean this phenomenon was few. 7) The species of food and their quantity of stomach contents had the tendency to increase in accordance with the change of hooked rate but concerning to Crustacea and Cephalopoda such a tendency was not seen. 8) All through the species of tuna, the selections for food were not so remarkable as far as I examined. / 西部印度洋海区で漁獲された胃の内容物を調査してマグロの種類別,海区別に比較検討し漁況との関係を求めた.(1) 鮪の胃内容物の魚種は大体30種位でキハダはメバチ,ビンチョウより出現率も高く出現尾数も非常に多い.(2) ミズウオ科,カマス科,ホウネンエソ科,カツオの若年魚は西部印度洋,小笠原近海,南太平洋海区共高い出現率を示している.甲殻類,頭足類に就ても同様である.従つて,ミズウオ科,ホウネンエソ科カマス科,カツオの若年魚,甲殻類のDecapoda,頭足類のDecapodaはマグロの餌料として重要な位置を占めている.(3) 西部印度洋海区に於けるマグロの摂餌量は小笠原海区,南太平洋海区より非常に多いことを示している.(4) マグロの胃内容物の魚類,甲殻類,頭足類の組成が似通つていることから,キハダ,メバチ,ビンチョウの3種間に食性に対する差異はないように思はれる.(5) キハダ,ビンチョウは季節の移行と共に摂餌量が増加し,メバチは反対に減少する時期的変化が見られた.(6) 南太平洋海区のマグロは空胃のものが殆どであるが印度洋海区は之と逆で空胃のものは非常に少い.(7) 釣獲率が高くなると共に胃内容物の魚類の出現率,出現尾数も増大し種類も多くなつて漁況と密接な関係があるように思はれる.但し甲殻類,頭足類では魚類の如く顕著な変化が見られない.(8) 西部印度洋に於けるマグロ類はその胃の内容物からして食餌に対する選択性が明であるとは考へられない.
URI: http://hdl.handle.net/10069/31930
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第6号

Citable URI : http://hdl.handle.net/10069/31930

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