Life cycle assessment of recirculating aquaculture systems: A case of Atlantic salmon farming in China

Recirculating aquaculture systems (RAS) are an alternative technology to tackle the major environmental challenges associated with conventional cage culture systems. In order to systematically assess the environmental performance of RAS farming, it is important to take the whole life cycle into account so as to avoid ad hoc and suboptimal environmental measures. So far, the application of life cycle assessment (LCA) in aquaculture, especially to indoor RAS, is still in progress. This study reports on an LCA of Atlantic salmon harvested at an indoor RAS farm in northern China. Results showed that 1 tonne live-weight salmon production required 7,509 kWh farm-level electricity and generated 16.7 tonnes of CO2 equivalent (eq), 106 kg of SO2 eq, 2.4 kg of P eq, and 108 kg of N eq (cradle-to-farm gate). In particular, farm-level electricity use and feed product were identified as primary contributors to eight of nine impact categories assessed (54-95% in total), except the potential marine eutrophication (MEU) impact (dominated by the grow-out effluents). Among feed ingredients (on a dry-weight basis), chicken meal (5%) and krill meal (8%) dominated six and three, respectively, of the nine impact categories. Suggested environmental improvement measures for this indoor RAS farm included optimization of stocking density, feeding management, grow-out effluent treatment, substitution of feed ingredients, and selection of electricity generation sources. In a generic context, this study can contribute to a better understanding of the life cycle environmental impacts of land-based salmon RAS operations, as well as science-based communication among stakeholders on more eco-friendly farmed salmon.