Sustainable Integrated Multi‐Trophic Aquaculture: Key Considerations for Assessing Environmental and Economic Performance

ABSTRACT

Integrated multi‐trophic aquaculture (IMTA), defined as the co‐production of species at different trophic levels, is conceptually appealing. By utilising complementary functions of different species, it holds opportunities for lower environmental impact, higher productivity, and increased profitability in comparison with conventional monoculture. However, whether those advantages materialise in practice remains unclear. Here we review available life cycle assessment (LCA) and cost–benefit analysis (CBA) studies of IMTAs to further the current understanding of environmental and economic performance. We find that, overall, LCAs conclude that IMTAs investigated have not been able to deliver on environmental promises, while CBAs generally find that IMTAs have both better financial performance and lower environmental externalities than monoculture equivalents. The main reasons for these contrasting findings include the nature of the systems assessed so far—often theoretical or experimental set‐ups with non‐optimised designs—combined with methodological choices in assessments. The findings of the review thus suggest that it is still unclear to what extent IMTA can deliver on its promises in practice, and that IMTA is no panacea for aquaculture but requires careful design to be effective for its intended use. Integrating robust LCAs and CBAs early in the development phase can help identify viable IMTA set‐ups based on key drivers of environmental and economic performance and, in this way, minimise the risks of misaligned practices. A first step towards realising the potential of IMTA is to carry out robust assessments that avoid key mistakes in both LCAs and CBAs, to which end we provide hands‐on recommendations for future assessments.