Growth and Production Characteristics of Palmetto Bass (Morone saxatilis female x Morone chrysops male) Reared at Three Densities in a Pilot-scale Recirculating Aquaculture System
Production characteristics of palmetto bass (Morone saxatilis female x Morone chrysops male) reared at three stocking densities (36 fish/m3, 72 fish/m3, and 144 fish/m3) in a pilot-scale RAS were evaluated. A final mean +SE fish weight of 412.1 + 7.8 g at the high density was significantly lower than that of fish at the medium density weighing 542.1 + 11.8 g (P < 0.05). Fish weight (676.1 + 17.0 g) at the lowest density was significantly higher than at the high and medium densities (P < 0.05). The average daily weight gain at the low density (2.8 g/d) was 22% and 47% higher than fish reared at the medium and high densities, respectively. Total biomass gains of 733.8, 483.3, and 297.9 kg were obtained at the high, medium, and low densities. Feed conversion and survival rates were similar among densities averaging 1.4 and 97.1%, respectively. Higher mean daily and cumulative feed totals at the highest density contributed to significantly higher ammonia and nitrite concentrations and lower pH levels at harvest. All other measured water quality parameters were similar among densities and remained within known acceptable limits for fish growth. The results indicated that palmetto bass reared in closed systems reached market size in 224 days at the low and medium densities. However, the relative biomass production may not justify such strategies when compared to the yield obtained at the highest rearing density.