Life cycle assessment of Finnish cultivated rainbow trout

Rainbow trout is economically the most important cultivated fish in Finland. In this study, new knowledge on the energy consumption, emissions and environmental impacts caused by the production of rainbow trout in Finland was generated. Methodologically the work was based on life cycle assessment (LCA) beginning from the extraction of raw materials and ending with the delivery of gutted fish to the retailers or for further processing. The environmental performances of production methods with different feeds, feed coefficients and technical emission reduction measures were assessed. The environmental impact assessment revealed that atmospheric emissions — originating mainly from the feed raw material production, feed manufacturing and transportation — make only a minor contribution to the total environmental impacts caused by the production of rainbow trout in Finland. Phosphorus and nitrogen emissions from fish farms to waters are the most significant emissions from the point of view of the total environmental impacts. By using new, environmentally friendly feeds with increased feed efficiency it is possible to decrease the nitrogen and phosphorus loads significantly. Technical measures to decrease nutrient emissions to the waters reduce the phosphorus load but have only a minor effect on nitrogen. Energy consumption and the use of renewable energy sources proved to be one of the key indicators for developing more sustainable aquacultural practices in Finland, although the major share of energy consumption associated with the production of rainbow trout takes place outside Finland.