Growth performance of Korean rockfish, dark-banded rockfish and rock bream in sea cage at Ulleung-do during winter season

Abstract

A 100-day feeding trial was conducted to investigate the growth performance of Korean rockfish (Sebastes schlegelii, initial mean weight of 36.2 g), dark-banded rockfish (Sebastes inermis, 78.3 g) and rock bream (Oplegnathusfasciatus, 72.0 g) in sea cage to evaluate the possibility of culture with each fish species at Ulleung-do during the period of January to April, 2016. Triplicate groups of each fish were hand-fed to visual satiety with commercial diet (42.2% protein) in two times (09:00 and 16:00) a day. Feeding trials were conducted in 9 rectangular net cages (2 × 3 × 3 m, mesh size 10 mm) with culture density of 400, 250 and 300 fish per each cage for theS. schlegelii, S. inermis and O. fasciatus, respectively.During the experimental period, water temperature, salinity and DO concentration ranged from 7.0 to 17.2℃, 33.2 to 34.2psu and 8.10 to 9.21 mg/L, respectively. At the end of experiment, the mean survival rate of S. schlegelii (93.9%) was significantly (P<0.05) higher than those of S. inermis(82.1%) and O. fasciatus (46.0%).The high mortality of O. fasciatuswas caused by as sudden water temperature decrease with inflow of cold water mass. The mean feed efficiency of S. schlegelii (81.5%) was significantly (P<0.05) higher than those of S. inermis (67.9%) and O. fasciatus (68.5%). The mean feed intake of S. schlegelii (0.35%/day) was significantly (P<0.05) higher than those of S. inermis (0.17%/day) and Og) in sea cage to evaluate the possibility of culture with each fish species at Ulleung-do during the period of January to April, 2016. Triplicate groups of each fish were hand-fed to visual satiety with commercial diet (42.2% protein) in two times (09:00 and 16:00) a day. Feeding trials were conducted in 9 rectangular net cages (2 × 3 × 3 m, mesh size 10 mm) with culture density of 400, 250 and 300 fish per each cage for theS. schlegelii, S. inermis and O. fasciatus, respectively.During the experimental period, water temperature, salinity and DO concentration ranged from 7.0 to 17.2℃, 33.2 to 34.2psu and 8.10 to 9.21 mg/L, respectively. At the end of experiment, the mean survival rate of S. schlegelii (93.9%) was significantly (P<0.05) higher than those of S. inermis(82.1%) and O. fasciatus (46.0%).The high mortality of O. fasciatuswas caused by as sudden water temperature decrease with inflow of cold water mass. The mean feed efficiency of S. schlegelii (81.5%) was significantly (P<0.05) higher than those of S. inermis (67.9%) and O. fasciatus (68.5%). The mean feed intake of S. schlegelii (0.35%/day) was significantly (P<0.05) higher than those of S. inermis (0.17%/day) and O