Recirculating aquaculture mode has high sustainability and environmental accommodation capacity via better energy-saving and water-saving effects in Cynoglossus semilaevis production

Recirculating aquaculture mode is a promising direction for future aquaculture development due to its energy, water, and land-saving advantages, high efficiency, and lack of seasonal restrictions. This study evaluated and compared the economic efficiency and environmental sustainability of Cynoglossus semilaevis production in flow-through and recirculating aquaculture modes using the economic methodology and the emergy analysis method. The results showed that: 1) The fixed investment cost for the recirculating aquaculture system was 2.188 times as that of the flow-through aquaculture system. 2) The recirculating water aquaculture mode saved 54.55 % of electricity, 93 % of coal, and 95 % of water compared with the flow-through aquaculture mode. 3) The recirculating aquaculture mode performed better in all breeding parameters than the flow-through aquaculture mode. In addition, the yield, tax revenue, and profit of the recirculating aquaculture system were 1.71 times, 1.71 times, and 2.98 times that of the flow-through aquaculture mode, respectively, and the break-even point was 4.35 %, indicating that the former has better risk resistance ability compared to the latter. 4) For the recirculating aquaculture mode the renewable energy value consumption was only 3.272 % that of the flow-through aquaculture mode, the non-renewable energy value input was 1.59 times that of the flow-through aquaculture mode, and the output energy value was 1.71 times that of the flow-through aquaculture mode. 5) The EIR value of the recirculating aquaculture mode was 48.89 times that of the flow-through aquaculture mode, and the EYR value was 1.069 times that of the flow-through aquaculture mode, which indicated that the recirculating aquaculture mode was less dependent on the environment and had higher production efficiency. 6) The flow-through aquaculture mode used 34.77 % of the environmental energy value input for aquaculture production. However, the uncontrolled use of groundwater and geothermal resources had caused great damage to the environmental ecosystem. To sum up, the recirculating aquaculture mode had higher sustainability and environmental accommodation capacity and could significantly reduce the pressure of aquaculture industry on the environment.