The Environmental Impact of Partial Substitution of Fish-Based Feed with Algae- and Insect-Based Feed in Salmon Farming

One of the key challenges for aquaculture is to reduce "fishing-for-feed". Alternative fish feeds need to be environmentally assessed to ensure they are sustainable. The present research consisted of an attributional LCA to (i) estimate the impact on salmon farming of a partially algal-insect-based diet vs a conventional fish meal/fish oil-based diet, (ii) identify the contribution of each process to the environmental impacts of the whole fish farming system, and (iii) identify potential improvements in the algal-insect value chain through sensitivity analysis of various algal-insect production pathways. The study shows that use of algal-insect-based feed resulted in a higher impact for most of the environmental impact categories due to fish feed production, particularly for soybean, insect, and algal meal. This points to the need to optimise production chains for new fish feed ingredients. Algal meal production using sugarcane sugar and optimised technology and insect meal using exhaust heat and renewable electricity would improve the environmental performance of salmon farming systems using insect- and algal-based fish feed. Methodological improvements with regard to system C and N cycle, biodiversity, and plastic use should be explored to inform policy making and support the implementation of sustainable future salmon farming innovations.