Environmental performance of rainbow trout (Oncorhynchus mykiss) production in Galicia-Spain: A Life Cycle Assessment approach.

Aquaculture is an increasingly important supplier of food worldwide. However, due to its high dependence on agricultural and fishing resources, its growth is constantly constrained by environmental impacts beyond aquaculture production systems. Within the European Union, Spain accounts for approximately 25 % of total aquaculture production, which implies that environmental impacts in rivers and marine ecosystems must be monitored to understand the role of aquaculture systems. While studies on the environmental performance of mussels or turbot production have been reported in the literature, Spanish rainbow trout (Oncorhynchus mykiss) has not received much attention despite its relative importance. In this sense, a Life Cycle Assessment (LCA) study of rainbow trout produced in a medium-sized plant in Galicia (NW Spain) was carried out in the present study. The study considered the production of round weight trout, as well as some commonly produced processed products, including filleting. The life cycle modelling included a high level of primary data in the foreground system. In addition to the widely considered environmental impact categories for this activity (e.g., global warming potential, terrestrial acidification and freshwater eutrophication), the recent proposed antibiotic resistance (ABR) enrichment impact category was included to explore the potential impact of antibiotic release in freshwater microbiota. The results highlighted the high contribution of aquafeed to most impact categories, due to upstream agricultural and fishing processes, whereas farm operation was responsible for the larger part of the impact in freshwater eutrophication, mainly due to direct emissions of nutrients from fish feeding. Amoxicillin release to recipient water bodies was the main driver to the ABR enrichment category. In contrast, the processing phase (i.e., gutting, freezing and packaging) showed low environmental burdens. In order to improve the environmental performance of the rainbow trout production system, decreasing the feed conversion ratio (FCR), shifting to renewable energy, using low environmental burden ingredients in aquafeed, and alternatives to control diseases without antibiotics could be considered.