海洋深層水で飼育されたニジマスOncorhynchus mykissの生残および成長(Survival and growth of rainbow trout Oncorhynchus mykiss reared in deep seawater)
- 標題
- 海洋深層水で飼育されたニジマスOncorhynchus mykissの生残および成長(Survival and growth of rainbow trout Oncorhynchus mykiss reared in deep seawater)
- 作者
- 岡本 一利, 高瀬 進(Kazutoshi Okamoto and Susumu Takase)
- 文件屬性
- 日本研究
- 知識分類
- 水產養殖
- 出版年
- 2006
- 刊名
- 海洋深層水研究
- 卷
- 7
- 期
- 2
- 頁
- P 1-6
- 點閱數
- 2733
摘要
海洋深層水 (以下, 深層水) を利用した養殖化の観点から, 通常, 淡水で養殖されるニジマスの飼育実験を行った.ふ化してから約9ヶ月間淡水で飼育された平均尾叉長8.6cm, 平均体重9.5gのニジマス111個体を, 深層水へ徐々に馴致しながら飼育を開始した.生残率の推移, 体色, 摂餌行動より, 飼育ニジマスは1週間で深層水に馴致したと判断した.飼育開始7日後までの生残数は31個体で, サイズ別生残率は, 尾叉長8cm未満が0%, 尾叉長8cm以上11cm未満が39.7%, 尾叉長11cm以上が100%であった.飼育開始330日後には9個体が生き残り, 平均尾叉長32.9cm, 平均体重628.6gで, 飼料効率は55.6%, 体色は銀色を呈し, 通常の淡水養殖の出荷サイズを超えるサイズまでの飼育に成功した.今回の飼育結果に基づき, 深層水でニジマスを養殖する場合の飼育開始から出荷目標サイズまでの所要日数と歩留まりについて推定した.海洋深層水の低温性, 清浄性, 高塩分により, 新タイプの商品の養殖生産が可能であることが示唆された.
Rainbow trout, Oncorhynchus mykiss, were reared in flowing deep seawater (DSW) pumped from a depth of 687 m in Suruga Bay. One hundred and eleven alive fishes (8.6 cm in fork length (FL) in average), cultured in freshwater (FW) for 9 months, were used for this experiment. These fishes were moved to 100% DSW on the 3rd day after acclimated in mixed waters (1/2 and 3/4 in DSW/FW ratios, 16.5°C) by adding DSW every day. They were reared at a temperature of 14.7°C for 330 days by feeding sufficient amounts of formula food daily. The survival rate of fish decreased from the 2nd to 6th day (particularly on the 4th day) but thereafter became stable (27.9% on the 7th day). The fishes were considered to be successfully acclimated to DSW after 7days because of their stability of survival, silver to white (smolting) body color and good appetite. The survival rates after initial depletion in three size classes (< 8 cm, 8-11 cm and ≥ 11 cm in FL) were 0, 39.7 and 100%, respectively. Of the 31 acclimated fishes, 9 fishes (29%) survived 330 (323) days after the start (completion) of acclimation. At the end of culture, alive fishes attained an average FL of 32.9 cm, which was larger than the commercial size in FW culture. Their body colour was silver to white, which was different from those obtained in FW culture. Although some techniques should be revised, these data and the estimated growth and survival patterns in the cases of acclimating larger juveniles (11 and 15 cm in FL) demonstrated the possibility of rainbow trout aquaculture using DSW. Because of its clean, cold and stable nature, use of DSW will support the health of cultured fish (i.e., decrease of pharmaceuticals against fish diseases) and in turn the safety as food.
Rainbow trout, Oncorhynchus mykiss, were reared in flowing deep seawater (DSW) pumped from a depth of 687 m in Suruga Bay. One hundred and eleven alive fishes (8.6 cm in fork length (FL) in average), cultured in freshwater (FW) for 9 months, were used for this experiment. These fishes were moved to 100% DSW on the 3rd day after acclimated in mixed waters (1/2 and 3/4 in DSW/FW ratios, 16.5°C) by adding DSW every day. They were reared at a temperature of 14.7°C for 330 days by feeding sufficient amounts of formula food daily. The survival rate of fish decreased from the 2nd to 6th day (particularly on the 4th day) but thereafter became stable (27.9% on the 7th day). The fishes were considered to be successfully acclimated to DSW after 7days because of their stability of survival, silver to white (smolting) body color and good appetite. The survival rates after initial depletion in three size classes (< 8 cm, 8-11 cm and ≥ 11 cm in FL) were 0, 39.7 and 100%, respectively. Of the 31 acclimated fishes, 9 fishes (29%) survived 330 (323) days after the start (completion) of acclimation. At the end of culture, alive fishes attained an average FL of 32.9 cm, which was larger than the commercial size in FW culture. Their body colour was silver to white, which was different from those obtained in FW culture. Although some techniques should be revised, these data and the estimated growth and survival patterns in the cases of acclimating larger juveniles (11 and 15 cm in FL) demonstrated the possibility of rainbow trout aquaculture using DSW. Because of its clean, cold and stable nature, use of DSW will support the health of cultured fish (i.e., decrease of pharmaceuticals against fish diseases) and in turn the safety as food.