Integrated multi-trophic aquaculture

Integrated multi-trophic aquaculture (IMTA) is a type of aquaculture where the byproducts, including waste, from one aquatic species are used as inputs (fertilizers, food) for another. Farmers combine fed aquaculture (e.g., fish, shrimp) with inorganic extractive (e.g., seaweed) and organic extractive (e.g., shellfish) aquaculture to create balanced systems for environment remediation (biomitigation), economic stability (improved output, lower cost, product diversification and risk reduction) and social acceptability (better management practices).

Selecting appropriate species and sizing the various populations to provide necessary ecosystem functions allows the biological and chemical processes involved to achieve a stable balance, mutually benefiting the organisms and improving ecosystem health.

Ideally, the co-cultured species each yield valuable commercial "crops". IMTA can synergistically increase total output, even if some of the crops yield less than they would, short-term, in a monoculture.

IMTA is also highly beneficial for reducing the environmental footprint of aquaculture. The growth of farmed Atlantic salmon (Salmo salar), provides insight to the rapid growth of aquaculture demand. Output growth rates averaged 25.6% from 1980 to 2004, with the economic value of farmed salmon output exceeding 4 billion U.S. dollars in 2004. IMTA works by creating a closed-loop system where the by-products such as excess nutrients and organic waste from fish farming, are utilized by other species such as shellfish and seaweed. This process can decrease water pollution, minimize the need for chemical fertilizers, and improve overall ecosystem health. Furthermore, by integrating different trophic levels, IMTA can enhance biodiversity and promote more sustainable practices in marine food production.