クロマグロ幼魚の飼育について

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[Author abstract]The tearing of young bluefin tuna obtainable in Japanese coastal waters had been considered extremely difficult because of their sharp sensitivity to handling them. The authors made some trials of rearing young bluefin tuna and confirmed that it was possible. The experiments were carried out at Shirahama and Kushimoto, Wakayama Prefecture. The fish experimented with at Shirahama were captured by troll. Twentyfive fish were captured on August 10 to 17, 1970 in the waters of Karekinada, carried to Shirahama, and kept in a floating net cage within 2 hours after they were fished. Some of them began to feed in the net cage after 3 days, being fed with meat of fishes such as mackerel, sand eel and anchovy. The survival rate of these fish was 28.0 percent on September 1,15 to 22 days after they were fished. The fish experimented with at Kushimoto were captured on September 10 and 11, 1970 by a kind of trap net set near the coast of Tsuyashima Island. Thirty-one fish captured were soon transferred to a net cage provisionally set at the same site and then to a rearing net cage set near the coast of Oshima Island off Kushimoto on September 12. It was observed that most of the fish in the net cage began to feed on September 12. They were fed with such fishes as anchovy, mackerel and sand eel. The survival rate of these fish was 87.1 percent on September 27, 16 to 17 days after they were fished. Throughout the experiments, young bluefin tuna seemed to feed well on such fishes as mackerel, anchovy and sand eel. The fish captured by troll were reared successfully, too, though the survival rate was much lower than in the fish captured by trap net. The fish captured on August 10 were 25 cm in total length and weighed 300g, grew to 33cm and 500 g on September 10 and further to 41cm and 1,072 g on October 25. This demonstrates the very rapid growth of young bluefin tuna.[摘要]1. 1970年8月10～17日紀伊半島西岸枯木灘でクロマグロ幼魚を釣によって捕獲して和歌山県白浜の近畿大学養殖場へ輸送し、網いけすで飼育した。2. 同年9月10～11日紀伊半島南端通夜島の沿岸定置網に入ったクロマグロ幼魚を和歌山県串本町大島地先養殖場へ輸送して同じく網いけすで飼育した｡3. その結果、いずれの場合も捕獲したマグロ幼魚の1部は捕獲後3～5日後からサバ、カタクチイワシ、イカナゴ等の冷凍生鮮魚を摂取し、成長がみられたが、捕獲後約半月の生残率は釣の場合は28%、定置網の場合は87%であった｡4. 死亡した魚は吻端、頭部、体側、尾鰭などに外傷があり、釣によって捕獲した場合の方がその率が高かったことから、死亡の原因は捕獲から養殖いけすへ収容するまでの取扱いによる損傷と考えられる。5. 今後捕獲時の取扱いの研究を進め,生残率を高めることができれば、ハマチ型の養殖がクロマグロにおいても行なわれ、それが親魚にまでも養成される可能性があると思われる｡
近畿大学の論文
1971-03-15

クロマグロ幼魚の飼育について

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