Comparative environmental impact assessment of aquafeed production: Sustainability implications of forage fish meal and oil free diets

The environmental sustainability of aquaculture food production systems is of critical concern due to its rapid expansion as the fastest growing major food production sector in the world. Among the parameters that contribute to the overall environmental impacts of aquaculture marine-based protein production, aquafeed is identified as an impact hotspot. There is consequently a need to seek more environmentally sustainable aquafeeds to mitigate the adverse environmental impacts associated with aquaculture food production. The environmental and economic sustainability of aquafeeds can be improved using two main approaches: (a) optimizing finite resources use (e.g. fish meal and fish oil), and (b) mitigating waste generation and emissions. A variety of ingredients have been previously proposed, investigated, and utilized to accomplish these strategies, while maintaining acceptable food production efficiencies. However, comprehensive evaluation of the environmental sustainability of aquafeeds with respect to variable ingredients, both in terms of resource use and waste emission has not been conducted. In this work, a holistic life cycle impact assessment of twelve practically formulated and utilized aquafeeds has been performed to provide a comparative evaluation of different aquafeed's environmental impacts, considering resource use (biotic resource use, water intake, and fossil fuel depletion) and emission-based impact categories (ozone depletion, global warming, photochemical smog, acidification, eutrophication, carcinogenics, non-carcinogenics, respiratory effects, and ecotoxicity). Results indicate that the investigated fish meal free diets do not, on the whole, result in a significant decrease in environmental impacts with respect to the use of biotic resources. However, if the substituted ingredients would not propose elevated impacts (e.g. blood meal), these diets can potentially lower the overall environmental impacts of aquafeed production mainly with respect to relevant emission-based indicators (e.g. global warming, eutrophication, ecotoxicity). Findings demonstrate that the investigated fish oil free diets can potentially lower the use of biotic resources. However, to prevent burden shifting, strategies to provide nutrient-rich oils with minimal energy requirement need to be undertaken.