- 著者
- YASUNORI ISHIBASHI HIDEAKI EKAWA HACHIRO HIRATA HIDEMI KUMAI
- 出版者
- The Japanese Society of Fisheries Science
- 雑誌
- Fisheries science (ISSN:09199268)
- 巻号頁・発行日
- vol.68, no.6, pp.1374-1383, 2002 (Released:2009-03-31)
- 参考文献数
- 50
- 被引用文献数
- 50
Nile tilapia were exposed to severe hypoxic conditions. The respiratory frequency (RF) of the fish reached a maximum level at approximately 10 mmHg PO2 and decreased gradually thereafter. The fish sank to the bottom and subsequently their respiration began to stop. The hypoxic conditions increased the hematocrit value. As RF decreased, plasma cortisol and glucose levels climbed drastically. Just before respiratory arrest, the ATP and the total adenylate (TA) concentrations were significantly depressed in the liver, kidney and ordinary muscle but not in the heart or gill. As RF decreased, ATP and TA in both the liver and kidney decreased rapidly. Cytochrome oxidase activity increased significantly in the brain, heart, gill and ordinary muscle until respiratory frequency peaked. However, from the peak RF, this activity decreased in the liver and kidney. Lactic acid levels in both ordinary muscle and liver increased markedly when the fish sank. These results indicate that the stress response to hypoxic conditions is induced markedly with the decreased RF. It is also suggested that the decreased energy status in the liver and kidney of tilapia occurs at the same stage as the metabolic depression in the whole body, without increases in the aerobic and anaerobic metabolisms.
- 著者
- HACHIRO HIRATA
- 出版者
- The Japanese Society of Fisheries Science
- 雑誌
- Fisheries science (ISSN:09199268)
- 巻号頁・発行日
- vol.68, no.sup1, pp.829-834, 2002 (Released:2008-06-30)
- 参考文献数
- 24
- 被引用文献数
- 1
The harmonization between aquaculture developments and the conservation of aquatic environments is the key to sustaining aquaculture. One of the obstacles to this harmonization is the negative economic relationship between developments and conservation. In order to sustain a systematic aquaculture, we need to establish benefits for both the human economy and the biological economy. The polyculture of Ulva and fish has been conducted by our group since 1964, with differing intents. Sakai was able to develop an abalone culture that fed on the Ulva cultured in the fish farm, and these mollusks produced green pearls as a byproduct of this fish culture. In that way, human profit was harmonized with the biological economy. The whole aqua-crop ensilage (WACE) system has been lectured by Hirata since 1999. The fish culture introduces nutrients into the sea. The nutrients contribute to the growth of sessile organisms. Whole organisms are harvested and ensilaged to produce the probiotic feed. This feed is mixed with routine fish feed. Ruminated culture will also be applied for byproducing the rotifer in culture of fish. These systems will be developed in the future.