Performance of a Lab-Scale Closed Seawater Recirculating System for Korean Rockfish Sebastes schlegeli Culture

Abstract

Performance of a laboratory scale closed seawater recirculating aquaculture system was evaluated. Twenty-kg of korean rockfish (130 fish) with an average body weight of 153.8g was stocked. Over a 107-day culture period, fish reached final density of <TEX>$51.7kg/m^3$</TEX> (initial density, <TEX>$33.3kg/m^3$</TEX>) on the basis of the culture tank volume. On a daily basis, added water amounted to 3.4% of the total water volume in the system. Total ammonia nitrogen (TAN) concentrations were below 1mg/l and nitrite nitrogen <TEX>$(NO_2-N)$</TEX> concentrations were within the range of 1-3mg/l on most sampling days. TAN was removed from bead and sand filters and it was removed or produced in the sedimentation basin. Basically, <TEX>$NO_2-N$</TEX> was removed in the bead and sand filters, while it was either removed or produced in the sedimentation basin. Nitrate nitrogen <TEX>$(NO_3-N)$</TEX> was produced in the bead filters and removed from the sand filter and sedimentation basin. The foam fractionator performed well in the recirculating system. The maximal daily removal values for total suspended solids (755) and protein were 10.9g and 1.4g, respectively. Whole water quality parameters were within the levels commonly recommended for fish culture on most of the sampling days. However, further studies are needed to evaluate the commercial feasibility of this system because of the smallscale system used in present experiment. At least, the present study still provides some basic information for further studies of this kind of system.