Factors affecting IMTA (integrated multi-trophic aquaculture) implementation on Atlantic Salmon (Salmo salar) farms

Abstract

Aquaculture operations are currently the fastest-growing food production industry, increasing output over 20 times in the past few decades alone. Waste production on “fed” aquaculture farms, like Atlantic Salmon, is an issue for management and public perception. Integrated Multi-Trophic Aquaculture (IMTA) is the co-cultivation of species from different trophic levels on an aquaculture farm; from a theoretical perspective, the metabolic waste and uneaten feed from the top-level species like Atlantic Salmon is used by lower-level trophic species like shellfish and macroalgae, minimizing the potential impact of these wastes on the ecosystem. Despite the theoretical benefits, IMTA is currently not applied as a mitigation measure in Atlantic Salmon farms. The main goal of this research was to determine the current state-of-the-art of IMTA and its potential to be effectively implemented on Atlantic Salmon aquaculture farms in a commercially viable manner. This study explored and investigated current methods, applications, uses, and mitigation efficiency of IMTA to address challenges on salmon farms through an in-depth PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) method literature review. Additionally, industry experts were surveyed to understand industry perspectives on IMTA effectiveness and the potential for use. Though surveyed industry members identified mitigation as a moderately viable benefit, the current literature indicates challenges related to scaling up the culture of extractive species to reach a meaningful mitigation level. Economic issues regarding capital and maintenance costs constitute bottlenecks for implementation. The lack of governmental support and commitment to implementation and innovation were repeatedly referenced among the literature review papers and the industry survey. Despite speculations on its viability, the fact that IMTA is not commonly implemented at the commercial scale constitutes a barrier for industry adoption. The next steps for IMTA could be related to the development of demonstration sites at the commercial level to showcase actual viability from a financial and managerial, economic, and environmental standpoint.