New technique might boost salmon farming sustainability in Canada

The Integrated Multi-Trophic Aquaculture (IMTA), is a new technique that can help improve the sustainability of salmon farming Canada.

According to The Ecologist, IMTA is built to recreate a balanced ecosystem within a fish farm.

Part of the problem with fish farming is that a large number of fish in a cage produce a large amount of waste, which floats through the bottom of the enclosure down to the seabed, where it can become a problem with pollution.

In an IMTA system, by-products of the fed species (excrement and uneaten food) are recycled to become inputs for at least two other species. Shellfish are grown to take in particulate organic matter, and seaweed species will use inorganic wastes, such as nitrogen.

Researchers are also experimenting with a fourth component to absorb larger organic matter, using various species of sea urchins or sea cucumbers.

At the moment, the IMTA concept is still in its infancy but an economist on the research team has determined that over a ten-year period encompassing five cycles of salmon, a farmer will make more money with IMTA than with a conventional monoculture model.

All of the components of an IMTA system are chosen for commercial value, as well as being native or indigenous to the Bay of Fundy region: mussels and kelp are the most common. Last year, the first crop of IMTA blue mussels was sold to markets in Maine, Quebec and California, with positive feedback.

In an effort to make the economics of the approach even more favourable, some are now looking to market the 'services' provided by the different trophic layers in the IMTA system.