Cross-national comparison and temporal dynamics of greenhouse gas emissions in Atlantic salmon and rainbow trout aquaculture (2003-2023)

National dynamics diverged substantially: Norway showed a sustained reduction in emission intensity driven by efficiency gains; Chile displayed interannual variability associated with marine environmental conditions; the United Kingdom and Canada maintained relatively stable emission profiles; and China achieved progressive intensity reductions through optimization of production systems and technological upgrading. Spatially analysis further revealed significant clustering of salmonid-related GHG emissions, with hotspots concentrated along Norway’s western coast, southern Chile (Los Lagos Region and Aysén Region), north-west Scotland, British Columbia, and the north-western plateau regions of China, underscoring the close coupling between farming intensity and regional ecological carrying capacity.

Collectively, these findings elucidated the evolving spatiotemporal structure of greenhouse gas emissions in global salmonid aquaculture and demonstrated a partial decoupling of emission growth from production expansion. This work will provide a robust quantitative basis for advancing low-carbon development pathways and designing regionspecific mitigation strategies for cold-water salmonid aquaculture.