The effects of feeding rates in juvenile Korean rockfish, (Sebastes schlegeli) reared at 17 A degrees C and 20 A degrees C water temperatures

摘要

Two feeding trials were conducted to determine the effects of feeding rates in juvenile Korean rockfish, (Sebastes schlegeli) reared at 17 and 20 A degrees C water temperature. Fish averaging 5.5 +/- A 0.2 g (mean +/- A SD) at 17 A degrees C and 5.5 +/- A 0.3 g (mean +/- A SD) at 20 A degrees C water temperature were randomly distributed into 18 indoor tanks. At each water temperature, triplicate tanks were randomly assigned to one of six different feeding rates: 2.8, 3.8, 4.1, 4.4, 4.7 % and satiation (4.99 % BW day(-1)) at 17 A degrees C and 2.8, 3.8, 4.1, 4.4, 4.7 % and satiation (5.0 % BW day(-1)) at 20 A degrees C. After 4 weeks of feeding trial, weight gain (WG) and specific growth rate of fish fed groups at satiation and 4.7 % (BW day(-1)) were significantly higher than those of fish fed groups at 2.8, 3.8 and 4.4 % (BW day(-1)) in both 17 and 20 A degrees C temperature. Feed efficiency and protein efficiency ratio of fish fed group at 2.8 % (BW day(-1)) was significantly lower than those of fish fed groups at 3.8, 4.1, 4.4 and 4.7 % (BW day(-1)) in both experiments. Hematocrit was significantly higher in fish fed group at 4.4 % (BW day(-1)) at 17 A degrees C, and there was no significant difference in hemoglobin content amongst all fish fed groups at 20 A degrees C. Glutamic oxaloacetic transaminase and glutamic pyruvic transaminase of the fish fed group at 2.8 % (BW day(-1)) were significantly higher than those of all other fish fed groups in both experiments. Broken line regression analysis of WG indicated that the optimum feeding rate of juvenile Korean rockfish was 4.48 % (BW day(-1)) at 17 A degrees C and 4.83 % (BW day(-1)) at 20 A degrees C. Therefore, these results indicated that the optimum feeding rate could be > 4.1 % but < 4.48 % at 17 A degrees C and > 4.4 % but < 4.83 % at 20 A degrees C. As we expected, current results have indicated that 5 g of juvenile Korean rockfish perform better at 17 A degrees C than at 20 A degrees C water temperature.