Rainbow trout farming in Recirculating Aquaculture System (RAS): An innovative and environmental friendly system

Abstract

The objective of this project was to test the feasibility of a recirculated aquaculture system in the bioclimatic conditions of the PEIMA. During the 3 year experiment, only 7.2 m3 of make-up water per kilogram of fish produced has been used instead of the 100 required for an open output circuit. The design of the system components allowed this sharp reduction without degrading water quality (N-NH4+: 0.66 ± 0.13 mg.L-1 ; N-NO2-: 0.12 mg.L-1 ± 0.03). The main indicators of animal performances were significantly improved (10 to 15% more weight gain and feed consumption ratio decreased by nearly 10%) and no impact on survival rate was observed. Reproduction was not affected by the rearing system (eggs survival rate: 67.03 ± 0.57% vs 62.65 ± 3.36%) and parasitism could be controlled. Flesh quality such as flavor has not been altered. Fillet and physicochemical quality of fillet (colour, texture, fat content) are only slightly affected by the rearing system. Despite its environmentally friendly characteristics its contribution to the European production is still small compared to cages, flow-through systems or ponds. The judicious combination of technical improvements in the recirculation loop and water treatment could improve the efficiency of the system in order to help the aquaculture industry to be less dependent on natural resources, while continuing to provide quality products to the consumer.