Pacific white shrimp (PWS) are the most popular species of farmed shrimp due primarily to fast growth and disease resistance. Clearwater recirculating aquaculture systems (RAS) are a viable way to grow marine shrimp in land-locked areas such as Kentucky. Increasing stocking density can enhance the productivity of a system, thereby boosting economic competitiveness. Horizontal substrate can help to increase sustainable stocking densities and may provide foraging opportunities as well as improved water quality. This project examined the implications of three intensive stocking densities in a clearwater RAS on the production of PWS. The experimental system consisted of nine, 1.2 m2, round fiberglass tanks with a shared sump and advanced filtration systems. Tanks were fitted with 5-layers of 0.8 cm mesh-size netting supported by a PVC frame, providing a total surface area of 41.8 m2 per tank.
PWS (2.9 g average weight) were stocked at three treatment densities: low-density (LD) = 1.50, medium density (MD) = 2.25 and high-density (HD) = 3.00 kg/m2 in three replicate tanks each. Shrimp were fed continuously utilizing 24-hr belt feeders based on an assumed FCR and growth rate, this was adjusted periodically based on gut fullness and leftover feed.
Results indicated that increasing stocking density generally led to decreased average weight while increasing overall biomass, which are common effects of density. However, the overall biomass (kg/m2) generated in this project is substantially higher than what has been reported previously. This finding demonstrates that clearwater RAS with horizontal substrate can support intensive shrimp production levels. Further studies should determine if the costs of technology and energy in such systems can be offset by the amount and quality of shrimp produced.