EVALUATION OF STOCKING DENSITY DURING SECOND YEAR GROWTH OF LARGEMOUTH BASS Micropterus salmoides RAISED INDOORS IN A RECIRCULATING AQUACULTURE SYSTEM  

Chelsea Watts*, Leigh Anne Bright, Shawn Coyle and James Tidwell
 
Kentucky State University
 Aquaculture Research Center
Frankfort, Kentucky, 40601
chelsea.watts@kysu.edu

Largemouth bass Micropterus salmoides (LMB) are a highly desirable food fish especially among Asian populations in large cities throughout North America. The primary production method for food-size LMB (> 500 g) has been outdoor ponds, and requiring two growing seasons (18 months). Indoor, controlled-environment production using recirculating aquaculture system (RAS) technologies could potentially reduce the growout period by maintaining ideal temperatures year-round.

Researchers conducted a 26 week study to evaluate optimal stocking densities for growout of second-year LMB to food-fish size in an indoor RAS. Largemouth bass fingerlings (112.0 ± 38.0 g) were randomly stocked into nine 900-L tanks to achieve densities of 30, 60 or 120 fish/m3 with three replicate tanks per density. The RAS consisted of a 3,000-L sump, ¼ hp pump, bead filter for solids removal, mixed-moving-bed biofilter for nitrification and a 400-watt UV light for sterilization. Fish were fed a commercially available floating diet (45% protein and 16% lipid) once daily to apparent satiation. At harvest all fish were counted, individually weighed, and measured.

Total biomass densities significantly increased (P ≤ 0.05) with stocking rate achieving 6.2, 13.2, and 22.9 kg/m3 for fish stocked at 20, 60 and 120 fish/m3, respectively. The stocking densities evaluated had no significant impact (P > 0.05) on survival, average harvest weight or feed conversion ratio which averaged 92.9 ± 5.8%, 294.5 ± 21.1 g and 1.8 ± 0.3, respectively. After approximately six months of culture LMB did not attain target weights of >500 g. Observed competition among fish likely resulted in large size variability and overall poor growth compared to second year growth in ponds. Additional research is needed to better assess the suitability of LMB for culture in RAS.