Integrated Multi-Trophic Aquaculture: a role in delivering the European Green Deal Frank Kane and Pauline O’Donohoe, Marine Institute What is the future of Irish Aquaculture? In general, there is a growing demand for more circularity in processes and more sustainable practices across all industries. Economic decoupling is a vital component of the European Green Deal, aiming to achieve economic growth while preserving a healthy environment. The aquaculture industry will be included in this shift to minimise or eliminate impacts, reduce waste, and increase circularity. The European Green Deal provides an opportunity for the Irish aquaculture sector to position itself as part of sustainable food production. Again, Ireland led the way with organic production and can again show how integrated multi-trophic aquaculture (IMTA). IMTA offers a potential avenue to enable aquaculture’s transition to a circular model while increasing productivity and supplying quality, sustainable seafood. The concept is a simple idea, where multiple aquaculture species are farmed on the same site or close to each other in an integrated and complementary way. The key element is the interactions on the farm or the bay between the different trophic levels (different
Lehanagh Pool Research Site, Marine Institute
levels in the food chain). The wastes produced by the fed species (e.g. fish) is utilised as a feed, fertiliser and energy source for the lower trophic filter-feeding and extractive species (e.g. shellfish and seaweeds).
waste (faecal matter, uneaten food) and dissolved matter (metabolic waste (nitrogen)), acting as a nutrient source for other species. The particulate waste serves as a food source for
This has the benefit of lowering the environmental load in the water and allowing a more circular and sustainable approach to farming. The concept of nutrient recycling reflects practices in agriculture, where manure is spread to fertilise fields and facilitate grass growth. The classic view of an IMTA set-up is based on a fed element (fin-fish) coupled with extractive species (shellfish and seaweed). The waste from the fed fish is in the form of particulate
Aquaculture & Seafood Ireland
Lobster on hand Lehanagh Pool
filter feeders and deposit feeders, while the dissolved waste serves as nutrients for seaweed production. This arrangement is doubly beneficial, as it increases growth in the extractive species and reduces the amount of waste material entering the environment, thus minimising any potential impact. The concept can be considered holistically; the nutrient balance within a biological area or bay facilitates the planning of IMTA systems to ‘balance’ aquaculture in a broader ecosystem. For example, freshwater IMTA systems utilise hydroponics to grow valuable plant species in nutrient-rich wastewater and reducing potential discharge impacts. 23
