Aquaculture innovations improve sustainability, diversify product lines and boost profitability
A seven-year research partnership in the Bay of Fundy is helping point the way towards the future of aquaculture. The research program, led by University of New Brunswick marine biology professor Thierry Chopin and Department of Fisheries and Oceans scientist Shawn Robinson, has earned a Synergy Award for Innovation for demonstrating that integrated multi-trophic aquaculture (IMTA) allows the aquaculture industry to reduce its environmental footprint while diversifying product lines and boosting profitability. (Click here to see the Video Presentation of the 2008 Synergy Awards).
“What we’re doing with IMTA is nothing less than recreating a simplified food chain within a balanced ecosystem,” Dr. Chopin says. “The problem has been that when you introduce too much of one species, you start to have shifts in equilibrium.” To solve that problem and more closely mimic a natural ecosystem, he and his colleagues added mussels and seaweeds to traditional salmon-only farming operations. Nutrients released from the salmon pens, which would normally be lost to the outside environment in a monoculture setting, are recaptured to become food and energy for the mussels and seaweeds. “While biomitigation is taking place, additional commercial crops are being cultivated,” says Dr. Robinson.
The approach has largely been developed through experiments at sites operated by industrial partner Cooke Aquaculture, with a second industrial partner, Acadian Seaplants, providing expertise on seaweed processing and marketing.
“In the Bay of Fundy, we had it all in place to do some innovative inter-disciplinary science, where we could mix biology, engineering, social science and economics. We pretty much have a live experiment in our hands,” says Dr. Chopin.
One of the project’s challenges involved choosing the right species based on their functions and roles in the ecosystem. Since introducing non-native species would only add another controversy, species selected have to be commonly found in the region. They also need to have a commercial value on their own, beyond what they bring as environmental service providers (mostly as nutrient “scrubbers”).
The most successful results so far have come from adding mussels and kelps to existing salmon farms, but Dr. Chopin and his team remain on the hunt for other organisms that will optimize the nutrient and energy recycling. “Mussels are good at filtering particles within a certain size bracket,” explains Dr. Robinson, “but we need other organisms for the bigger particles.” Potential additions to the mix include sea cucumbers, sea urchins and sea worms.
The well-established agricultural practice of crop rotation could also become part of the IMTA approach. “We have to completely rethink the design of aquaculture sites and their operation as we continue to refine this responsible aquaculture practice,” Dr. Chopin says.
The research team had to develop various technical innovations along the way, such as cultivation systems and rafts configured to grow different types of shellfish and seaweeds. They also had to determine the best location for each crop based on a variety of factors, including currents and tides. Mussel rafts, for example, are best located within about 20 metres of the salmon pens, while seaweeds, which feed on dissolved inorganic nutrients instead of particulate organic matter, can be around 100 metres away. “Modelling the biomitigation efficiency of IMTA systems is not that simple and much more research is needed,” says Dr. Chopin.
