Environmental Impacts of Salmonidae Farming: A Systematic Review and Meta Analysis of Life Cycle Assessment Studies

Abstract

Salmonidae farming is a cornerstone of global aquaculture, but growing concerns about its environmental impacts highlight the urgent need for improved understanding and mitigation strategies. To address this, a systematic review of 31 life cycle assessment studies was conducted, with 15 providing sufficient data for in-depth meta-analysis. The global warming potential (GWP) results indicate that Salmonidae farming generates a median of 2570 kg CO₂-eq per tonne of live weight, with an interquartile range of 2032–3802 kg, of which approximately 65% is attributed to feed production. Eutrophication potential (EP) was measured at 42.6 g PO₄³⁻-eq/t (range: 23–66), with 24% linked to feed, while acidification potential (AP) was 15.85 g SO₂-eq/t (range: 10–28), with 68% from feed. Energy demand (ED) was found to be 54,365 MJ/t (range: 32,576–113,000), with 48.6% attributed to feed inputs. The feed conversion ratio significantly influenced GWP, EP, and AP outcomes. Meta-analysis revealed that flow-through systems have a lower GWP (effect size = −0.24) compared to recirculating aquaculture systems (RAS), which showed a notably higher GWP (4.31). While RAS systems significantly reduce EP (−5.11), net-pen systems contribute moderately to EP (0.38). However, differences in GWP and EP between production systems were not statistically significant. Notably, most reviewed LCA studies lacked detailed feed composition data and did not fully quantify nitrogen emissions, limiting the accurate assessment of marine eutrophication impacts. Future research should prioritize improving LCA data quality, optimizing feed efficiency, and developing sustainable farming practices to further reduce its environmental footprint.