Relationship between the oxygen reduction rates of culture cage of red sea bream Pagrus major and the tidal range

Management of the oxygen environment in fish culture farms is a fundamental factor in the development of sustainable mariculture. In order to analyze the environmental conditions of mariculture farms, the dissolved oxygen and water temperature were observed by monitors (HYDROLAB Data Sonde 3) set both sides of the culture cages. The red sea bream Pagrus major were cultured in two cages. Total fish body weight were 5,536 kg (1.73 kg in average×1,600 individuals×2 cages). The monitors-A and-B were set in the upper and lower sides of the cage, respectively. The oxygen reduction rates of the cultured cages were recorded every ten minutes for 15～23 days. Five observations were made in 2000 ; the 1st observation in January, the 2nd one in April, the 3rd one in July, the 4th one in November, and the 5th one in December. The fish were fed dry pellets by an automatic feeder between 10 am to 12 am from Monday to Wednesday through the experiments. No pellets were supplied between Thursday and Sunday. The oxygen reduction rates of the cages were 97.8 to 100% related to the tidal ranges in winter. However, the rates were 39.3 to 50.9% in regarded to the ranges in summer. The fish in the monitored area were fed more actively by the farmers in summer than in winter. It is suggested from these results, the relationship between oxygen consumption and tidal range has been more complicated and moderated in summer.記事区分：原