25th July 2018
A potential milestone in fish farming was reached in America recently as the first land-based Atlantic salmon (Salmo salar) went on sale to the general public. Wisconsin company Superior Fresh are, to date, the only facility in America growing salmon in a land-based system.
There is increasing pressure globally on traditional sea-based salmon pen or cage farms to seek alternative methods of supplying fresh fish given the huge environmental impacts the farms cause to wild salmon and sea trout stocks, among others. Sea lice is the major issue affecting wild stocks nearby such farms, causing mortalities through abnormal numbers of parasites. Sea-based farms also pose serious risk to the genetic health of wild populations of salmon through escapees, which find their way out of farms and into the wild where they interbreed with native stocks. Farmed fish are typically inferior in terms of survival, migration ability and overall fitness compared to their wild counterparts.
However, Superior Fresh may be about to lead the way in closed recirculating aquaculture systems (RAS). Fish farms on land, whilst not without impacts, are highly preferable to those based in sea bays and fjords as farmed fish cannot simply escape and impacts to nearby ecosystems are all but eliminated. Production in a closed system is also possible year-round, unlike sea-based facilities.
Superior Fresh uses a recirculating aquaculture system (RAS) which re-uses 99.9% of its water because leafy greens grown in a three-acre hydroponic greenhouse take up excess nutrients. The water is fed from the RAS to a hydroponic system where by-products are broken down by nitrifying bacteria into nitrites then nitrates. After the nitrates are utilised by the plants the clean water is recirculated back to the aquaculture system with virtually zero waste. This makes is highly sustainable.
Clarifying the quality of the land-based salmon product, Manager of scientific research at the company Steve Summerfelt added, “They never see pesticides, herbicides, or antibiotics. These fish are literally priming the pump for the expected growth in US land-raised Atlantic salmon production in the next several years.” He also added, “We have zero discharge from the production and processing systems. In addition, every ton of fish feed produces almost one ton of Atlantic salmon plus close to 10 tons of certified USDA organic salad greens.”
Given all the issues associated with traditional modern fish farming, surely this is the future of salmon production?