Can wild Atlantic and Pacific salmon be saved from extinction if floating, net-pen fish farms are replaced by contained fish farms on land? The answer has always been a hopeful yes, but until now, economic and technological barriers made closed-containment systems just a pipe dream. Now, land-based recirculating aquaculture systems (RAS) are proving they are not only economically viable, they are potential saviors of our ocean environments.
In a nutshell, here’s why floating open-net fish farms have failed: Although they have provided most of the Atlantic salmon sold to consumers in the past two decades, the farms have caused outbreaks of infectious salmon anemia (ISA) in the Bay of Fundy and Chile, been identified as potential contributors to recent declines of Fraser River sockeye runs due to pollution and parasitic sea lice, and lost the support of the consumer public because of the dangerous chemicals used to control disease and parasites and produce massive growth in farmed fish. [For a full accounting of these failures, and the magnitude of the threats they present to both Atlantic and Pacific salmon, read John Randolph’s abbreviated history of the Bay of Fundy wild Atlantic salmon decline, and the coincidental contemporary decline of Fraser River sockeye at flyfisherman.com/?p=17976. The Editor.]
Virtually all the pen-raised Atlantic salmon produced in North America are raised in Canada—and until recently all were raised in adult-stage net-pens located in saltwater estuaries.
A March, 2013 “Report of the Standing Committee on Fisheries and Oceans” to the Canadian Parliament outlines what many in Canada (and the U.S.) are viewing as a possible solution to net-pen problems.
The report is the second of its kind. The first, conducted in 1999-2003 and called “The Federal Role of Aquaculture in Canada,” contained just one recommendation pertaining to closed-containment aquaculture. But the new 2013 report says: “As a result of increased scrutiny on the environmental impacts of the aquaculture industry, closed-containment technologies have become a major focus of aquaculture research and development. The fact that this report focuses entirely on closed-containment aquaculture indicates how much the dialogue has changed over the last decade.”
Since the 2013 report was submitted, two on-land RAS operations in Canada have begun raising and selling Atlantic salmon and Arctic char. Both operations are owned by Sustainable Blue (sustainableblue.com) in Nova Scotia.
In the U.S, the Conservation Fund’s 20-year-old Freshwater Institute in Shepherdstown, West Virginia, partnering with the Atlantic Salmon Federation—and partially funded by the U.S. Department of Agriculture and private endowments—finished a two-year experimental project growing Atlantic salmon smolts in an indoor recirculating aquaculture system (RAS) that recycles water for the fish and captures 98 percent of the waste material.
It was the first American project of its kind to successfully produce Atlantic salmon in a closed-containment system—and send them to market (20 metric tons of 8- to 10-pound fish).
The RAS operations offer the following advantages: Little use of, and no discharge of, antibiotics and pesticides into the marine environment; no amplification of or spread of sea lice; the ability to contain and control bacteria and viruses and prevent them from entering the marine environment; no discharge of fish waste into the environment; no fish culling and entanglement of marine mammals and birds in nets; no escape of nonindigenous species, thus avoiding invasive, competitive inbreeding with native species of salmon such as has happened in the Bay of Fundy.
The production benefits over net-pen aquaculture include: faster (year-round) growth; less feed required (a pound of feed produces a pound of salmon, about the same food/fish ratio as ocean net-pen farmed salmon); no loss of product due to disease or parasites; the ability to collect and use feces as aquaponics recycle-system fertilizer; and the ability to locate farms near markets.
The production costs are projected to be close to, or below, the net-pen cost of production—about $1.80 per pound. But capital RAS start-up costs are much higher: $30 million for construction of an RAS versus $10 million for a net-pen operation. According to Canadian restaurateurs who have served them, the taste and meat quality of RAS salmon are as good as ocean aquaculture salmon.
The science-based RAS systems forestall all the documented environmental threats that sea-based, open-net-pen systems brought to the salmon estuaries and rivers of the Northern Hemisphere and Chile. And they do so at much lower environmental costs.
According to the Freshwater Institute’s Director of Aquaculture Systems Research Steven T. Summerfelt, Ph.D., and Director of Engineering Services Brian J. Vinci, Ph.D., the present and future of land-based closed-containment aquaculture is proven and inevitable. They say:
“U.S. farmers are first in cattle and poultry production in the world and second in hogs, with total terrestrial production of nearly 38 million tons per year, but the U.S. produces less than 1 percent of this biomass using fish farming.
“Simply put, fish-farm expansion in the U.S. has been constrained by limited water resources, site access, and regulatory limitations. Due to these constraints, to create significant new production we must develop technically advanced, environmentally compatible, and economically sustainable production systems and techniques for species with strong market demand, such as Atlantic salmon.
“The U.S. consumes approximately 300,000 tons of farm-raised Atlantic salmon annually, but farms less than about 20,000 tons.
“Arguably, all fish farms in the U.S. are CAFOs (concentrated animal feeding operations). However, only pond systems and land-based, closed-containment systems can still be widely sited and permitted in the U.S. due to our water and regulatory constraints. Land-based, closed-containment systems use water recirculation technologies that continuously filter and recycle as much as 99.8 percent of the water flowing through the system, and have only minimal direct hydraulic interaction with the environment. During the recycling process, land-based, closed-containment systems can control and capture 99 percent of fish waste solids and phosphorous, plus much of the nitrogen.
“Therefore, large-scale fish-farm operations employing these technologies can be located in areas adjacent to major U.S. markets or with minimal siting restrictions, limited water resources, strict discharge regulations, or cheap electricity.
“In addition, land-based, closed-containment systems allow for much greater control of the rearing environment than ponds, flow-through net-pen, or floating-tank systems. Water temperature and quality can be maintained at optimum levels; multiple barriers can be used to prevent fish escapement; protection from storms, wildlife, and vandals can be achieved; implementation of biosecurity strategies can improve fish welfare by minimizing disease and result in healthy fish, and negligible use of antibiotics or chemicals.
“Nutrients can be concentrated into much smaller volumes, resulting in a manageable effluent (one that can be disinfected) and significantly less waste discharge to the environment; and phosphorus, nitrogen, carbon, and nutrients can be recaptured for reuse as a soil amendment, to feed vegetables and herbs in large-scale aquaponics systems, or for methane production.”
How it Works
The Freshwater Institute system uses fresh water drawn (5 to 30 gallons per minute depending on the season) from a karst limestone spring creek and fed into a hatchery house containing a 40,000-gallon circulating growing tank, where thousands of healthy 8- to 10-pound Atlantic salmon swim, knifing into the cool (58 degrees F.) circulating current.
The population is mixed males and females. The males are harvested early—prior to maturation due to lower-than-premium (pale in color) fillet quality. Most commercial net-pen salmon operations use exclusively female salmon to eliminate problems with early-maturing males.
The adult salmon at the Freshwater Institute came from Cascade-strain fertilized (eyed) eggs purchased from American Gold Seafoods on the West Coast and shipped chilled overnight to the hatchery.
The two-year egg-to-adult growing cycle begins when the eggs are hatched into larvae in trays (one month hatching and incubation), and raised for six to seven months in a larval/juvenile rearing system, where they are photoperiod-manipulated to induce smoltification.
The smolts are then moved to a cleaner, freshwater “depuration” system for about a week, which allows their systems to cleanse of any bacteria that can cause a musty flavor in the fillets. Then they are raised for three to four months to post-smolt size.
The post-smolts are finally introduced to the large “grow-out tank,” where they grow swiftly, fed fish pellets three to four times a day, to near 3-kilogram size in six months and finally, in the last six months, to 4 or 5 kilogram weights. Then they are euthanized instantly—to prevent buildup of lactic acid in their flesh—by a cranium stunning piston. Summerfelt says his operation can grow the salmon four to nine months faster than net-pen operations due to its ability to control the “culture environment,” particularly the water temperature.
The harvested adult fish are shipped on ice swiftly to Albion Seafoods in British Columbia, where they are processed and marketed. The most expensive cost (both financially and environmentally) in the whole process is the fish pellets (made from ground-up menhaden and other saltwater baitfish.)
The fish excrement is separated at the bottom of the tank, which carries a small flow to a settling device. The nutrient-rich wastewater separated from the fish system is ready for use in growing various lettuces and other vegetables. (The Freshwater Institute plans to add an aquaponic veggie garden in the near future; the fish waste is currently shipped to a municipal waste plant.)
Summerfelt’s system is entirely closed, except for a small amount of treated wastewater, tested as clean under a National Pollution Discharge Permit. It is entirely disease free, and it has never lost a salmon (smolt or larva) to nearby streams.
As Senior Research Associate John Davidson III says, “The system engineering design was created here by Dr. Summerfelt and our engineering team through extensive technological research. It’s completely closed, and it can be recreated anywhere on land. All it needs is clean, cold water.”
The Summerfelt-designed RAS is an elegant example of biochemical/technological innovation, proof in operation that science-based, reliable onshore commercial aquaculture is here. It is now the confirmed present and future of safe aquacultural fish products in North America. And it is the technology that should save our wild salmon.
However, as Summerfelt points out, the future of RAS systems in the U.S. depends on large-scale (40- to 100-ton) salmon productions being built, and—most important—showing that they can be profitable.
Is it the future of fish farming? Well, it could be, but only if consumers prefer or even demand salmon from these new, closed-containment producers.
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