Growth performance of juvenile Korean rockfish Sebastes schlegelii experienced ration size restriction in sea cage

Abstract

A 330-day feeding trial was conducted to determine the influence of ration size restriction on growth of juvenile Korean rockfish Sebastes schlegelii (mean body weight 78.0 g) in order to investigate optimum feeding regime for enhancing the growth rate of the species under an ambient water temperature in sea cages. A total 4,000 juveniles were used in this experiment, from which 500 juveniles per cage were randomly distributed to 8 cages. The fish were hand-fed with a commercial diet (46.7% protein) at one of four different ration size trials [40%, 60%, 80% and 100% (control) of satiation] with duplicates. The control fish were fed to apparent satiation once a day. The feed allowance of fish in the rest of thethree groups was determined based on average feed consumption fish of the control group. At the end of experiment, the mean final weight of fish fed 40%, 60%, 80% and 100% of satiation were 216.0, 242.4, 265.3 and 266.4 g, respectively. The weight gain and specific growth rate of fish fed 80% and 100% of satiation were significantly (P < 0.05) higher than those of fish fed 40% and 60%. As the decrease of ration size from 100% to 40% of satiation, the feed efficiency of fish significantly (P < 0.05) increased from 29.5% to 64.6%. Based on the results, we concluded that the optimum ration size restriction for optimized growth of juvenile Korean rockfish weighing from 80 to 270 g reared in sea cages in 60% of sati growth rate of the species under an ambient water temperature in sea cages. A total 4,000 juveniles were used in this experiment, from which 500 juveniles per cage were randomly distributed to 8 cages. The fish were hand-fed with a commercial diet (46.7% protein) at one of four different ration size trials [40%, 60%, 80% and 100% (control) of satiation] with duplicates. The control fish were fed to apparent satiation once a day. The feed allowance of fish in the rest of thethree groups was determined based on average feed consumption fish of the control group. At the end of experiment, the mean final weight of fish fed 40%, 60%, 80% and 100% of satiation were 216.0, 242.4, 265.3 and 266.4 g, respectively. The weight gain and specific growth rate of fish fed 80% and 100% of satiation were significantly (P < 0.05) higher than those of fish fed 40% and 60%. As the decrease of ration size from 100% to 40% of satiation, the feed efficiency of fish significantly (P < 0.05) increased from 29.5% to 64.6%. Based on the results, we concluded that the optimum ration size restriction for optimized growth of juvenile Korean rockfish weighing from 80 to 270 g reared in sea cages in 60% of sati