Introduction
IMTA is an innovative option for enhancing the sustainability of aqu aculture. By culturing a combination of low trophic and higher trophic species, the co-products of one crop are converted into fertilizer, food and energy for the lower trophic species. IMTA is shown to increase circularity and reduce waste from fed species and lower the nutrient load in the water (FAO, 2018). IMTA systems can reduce environmental impacts, diversify and increase production, lower investment risks, create jobs, increase consumers’ trust, as well as support sustainable aquaculture and the circular bioeconomy (Chopin, 2015).
Methodology
RAS Biofloc System Brazil, d uring super-intensive shrimp production without water renewal, there is an accumulation of nutrients. The integration of IMTA species consuming biofloc (tilapia and oysters) and dissolved nutrients (seaweeds and halophytes) has been investigated to diversify products and maintain water quality. Land-based Pump Ashore System South Africa cultivates abalone in raceways with the green alga, Ulva , grown in adjacent interconnected paddle raceways using abalone effluent. Ulva serves as a biofilter allowing for increased water re-circulation and is used as a supplementary abalone feed . Sea urchins (Tripneustes gratilla ) have also been trialled in this system. Open-W ater System Scotland optimises cultivation techniq ues of macroalgae and shellfish, kelps and native oysters. The development of new cultivation systems explores options to minimise cultivation wastes through improved system design and reducing, reusing, and recycling polymer-based cultivation materials. Open-Water System Ireland explores the feasibility of the cultivation of Atlantic salmon, cleanerfish, European lobster, native oysters, scallops, seaweeds and spiny sea urchins in one IMTA system . Production technologies are assessed and optimised to enhance profitability and to mitigate environmental impact. Prospective IMTA Argentina, feasibility studies were carried out to assess local species (fish, crustacean, mollusc and echinoderm) and to identify appropriate sites within the Beagle Channel to facilitate IMTA.
ASTRAL is examining the potential of these IMTA value chains throughout the growing seasons to establish criteria for optimal production conditions. M onitoring continues to establish baseline data for better yield and profitability, reduction of environmental impacts and the reduction of waste.
Chopin, T. 2015. Marine Aquaculture in Canada: Well-Established Monocultures of Finfish and Shellfish and an Emerging Integrated Multi-Trophic Aquaculture (IMTA) Approach Including Seaweeds, Other Invertebrates, and Microbial Communities. Fisheries 40, 28-31.
Acknowledgements
This work is part of the ASTRAL project, funded by the EU H2020 research and innovation programme under Grant Agreement No. 863034.