Aspiring for environmentally conscious aquafeed: comparative LCA of aquafeed manufacturing using different protein sources

Aquaculture, the cultivation of aquatic organisms for the human consumption, is one of the fastest growing animal production activities worldwide. The sustainable sourcing of aquafeeds for fish nutrition is considered one of the main priorities to reduce the environmental impact of this industry. In our study, we used consequential life cycle assessment (LCA) to model the environmental impact of trout feed manufacturing using different scenarios of fishmeal, soybean meal and rapeseed meal based protein sources for aquafeed formulations. In a cradle to factory-gate assessment of fishmeal-based standard trout feed, the impact categories acidification potential (AP), global warming potential (GWP), eutrophication potential (EP) and land competition (LC) were 8.7 kg SO2 equiv., 1797 kg of CO2 equiv., 2.0 kg of PO4 equiv. and 1065 m²a per tonne of aquafeed, respectively. Results indicate that fishmeal-based aquafeed has considerably higher impact on the environment as compared to plant protein based aquafeeds across all the impact categories, where impacts of a soybean meal based aquafeed for AP, EP, GWP and LC were 6.49 kg SO2 equiv., 1.72 kg of PO4 equiv., 1019.65 kg of CO2 equiv. and 806.79 m²a per tonne, respectively; and a rapeseed meal based aquafeed resulted 6.56 kg SO2 equiv., 1.72 kg of PO4 equiv., 1037.13 kg of CO2 equiv. and 806.96 m²a per tonne for AP, EP, GWP and LC, respectively. These impact results were sensitive to changes in different marginal energy uses. Moreover, comparison of the different methodological approaches between attributional and consequential approaches of LCA resulted in considerably large differences; consequently, system expansion using consequential LCA is identified as the most appropriate method to evaluate the impacts of aquafeed.