What is it…
Integrated Multi-Trophic Aquaculture (IMTA) refers to the farming of different aquaculture species together in a way that allows one species’ wastes to be recycled as feed for another. Typically, IMTA systems combine an aquaculture species that requires external feeding (e.g. salmon and other finfish) with species capable of deriving nutrients from the wastes of the ‘fed’ species. By recycling nutrients that would otherwise be wasted, IMTA systems offer aquaculturists the potential of increased economic gains. IMTA systems could also lead to "greener" aquaculture practices through the reduction in waste products in the marine environment – as well as a decreased risk of algal blooms and cloudy water.
Where it’s practiced…
IMTA is still in the developmental stages. In a pilot project in the Bay of Fundy, New Brunswick, Canadian researchers are investigating the benefits of rearing Blue mussels and kelps near pre-established Atlantic salmon aquaculture sites. In this system, any feed not eaten by the salmon – together with other organic wastes – is then available as a nutrient source for the mussels. As part of their natural metabolic processes, both the salmon and the mussels release soluble ammonia and phosphorus – thereby also providing essential nutrients for the kelps. This nutrient abundance is having a positive impact on the growth of both species: the mussels reach market size 8-10 months earlier than normal – and the kelps grows 46% more. The mussels produced by the IMTA system would be ideal for the restaurant and retail trade – while markets for kelps include food, nutraceuticals, and other applications.
In British Columbia, the Pacific SEA-lab has developed a small, commercial scale IMTA facility that is currently investigating the potential of combining sablefish, scallops, oysters, cockles, sea cucumbers, and kelps in an intensive IMTA system design. This pilot IMTA initiative, also referred to as a Sustainable Ecological Aquaculture (SEA-System), is supported through an industry-academia partnership that is exploring the environmental and socio-economic benefits associated with this form of integrated aquaculture.
Chopin Lab: www.unbsj.ca/sase/biology/chopinlab/
Bay of Fundy pilot project: www.dfo-mpo.gc.ca/aquaculture/sheet_feuillet/polyculture_e.htm
Cooke Aquaculture: www.cookeaqua.com/index.php?id=31
Pacific SEA-lab: pacificsea-lab.com
Aquaculture Assoc. of Canada:www.aquacultureassociation.ca/bulletin/Bul104-3.pdf