Farmed salmon continues to one of the most problematic entrees on America's dining room tables. While popular and inexpensive, it also has one of the worst reputations for environmental impacts of any seafood.
Yet a handful of forward-thinking salmon farmers are innovating new ways to raise this fish – to lessen the impact on our ocean environments, coastlines and natural fish populations. This is one of a series of innovative practices that have the potential to radically change how salmon is farmed, if they are widely adopted by the farmed salmon industry.
One of these innovations is Integrated Multi-Trophic Aquaculture (IMTA) , a very old idea that is being used to reduce the considerable pollution generated by salmon farms. The basic idea behind IMTA is this: growing lots of plants and animals together uses resources more efficiently by mimicking nature – where nothing goes to waste.
First some background: Since salmon farming happens in the open ocean, waste from uneaten feed and excrement from the salmon cages is directly released into the ocean. These wastes can cause algal blooms, alter the types of animals that live under the cages and reduce the water quality – all of which undermine a healthy ocean ecosystem.
Waste happens even with the best feeding practices, but one farm found a way to use the principle of IMTA to turn these wastes into extra income, reduce its financial risks and reduce its impact on the environment.
Cooke Aquaculture in New Brunswick, Canada has partnered with the University of New Brunswick, St. John, to build an IMTA site at a farm to grow seaweeds, mussels and (coming soon) sea cucumbers alongside traditional salmon pens. This farm uses the waste from the salmon pens to feed these other species, so that the only feed added to the system is for the salmon.
Not only does this reduce the amount of waste entering the ocean, but it also provides additional crops for the salmon farm to sell. Estimates show that using an IMTA system can bring in 10% more profits than farming salmon alone. More importantly, if the salmon crop fails, the IMTA system can keep the farm from going bankrupt.
More money, less risk for the farmer, less impact on the fragile ocean ecosystem: Now that's a good idea that the rest of the farmed salmon industry should consider.
* Teresa Ish is an international expert on aquaculture sustainability standards and a consultant to EDF's Ocean Program. This the first in a series of eight blog posts about innovations in salmon farming. Teresa can be reached at firstname.lastname@example.org.