Producing healthy sustainable fish

 By RP Siegel

With all of the information circulating about the health concerns associated with the consumption of red meat, a lot of people are turning their attention, and their skillets, towards fish. But even that choice has become fraught with concerns regarding overfishing, mercury in the oceans and pollution associated with farmed fish. Now there is a new option that appears to be free of those concerns and better for the planet as well…

These days, we get a lot of mixed messages about what foods are healthy and not healthy to eat. Whether it’s red wine, or certain fats, coffee, or many other foods, some experts tell us they are good for us, while others shake their heads. Fish was always considered healthy, until recently. Now we hear concerns about mercury levels in wild-caught fish and agricultural runoff contaminating farmed fish.

With billions more people joining our population, and concerns about climate impacts of raising beef and other livestock, where are all these people going to get their protein?

Fortunately, there is some good news on this front. A novel approach to raising fish in a clean, wholesome and sustainable way called a recirculating aquaculture system (RAS) is catching on in the US. As we shall see, RAS has numerous advantages over other systems that will likely lead to widespread adoption.

Recirculating aquaculture system (RAS)

The RAS system was pioneered by the Freshwater Institute, a program of the non-profit Conservation Fund, whose goal is to link conservation with prosperity. The Freshwater Institute is a research center, which developed this scalable system of raising fish, specifically salmon and trout, indoors in tanks with a high-tech water filtration system to maintain pristine conditions for the fish, isolated from the outside environment. This means that not only do the tanks remain pure, but so does the surrounding environment. Waste is filtered out, and collected so that it can be used to fertilize crops. The fact that it’s all done indoors means that it can be replicated anywhere, even in deserts on the tops of mountains far from the nearest ocean. Fresh local fish could soon be a part of anyone’s diet, anywhere.

The first commercial-scale facility is now gearing up for production in the town of Hixton, WI, outside of Eau Claire, two hours East of the Twin Cities. This facility will take the concept a step further, as it will synergistically combine recirculating aquaculture with indoor production of leafy greens, using nutrients derived from one, to feed the other.

The Superior Fresh facility consists of a 123,000-square foot hydroponic greenhouse, connected through an intricate “nutrient management system” of filters and pipes to a one acre fish house. The greenhouse will produce the equivalent of 16,000 heads of lettuce per day, while the fish house will produce 120,000 pounds of Atlantic Salmon plus 40,000 pounds of trout, annually. Altogether, that’s 2.2 million pounds of food per year. The entire process will be vertically integrated to a very high degree. There is a high emphasis on maintaining premium water quality for the fish, using technology developed at Freshwater, who helped design the facility.

Superior Fresh business

Steve Summerfelt, Director, Aquaculture Systems Research at The Conservation Fund’s Freshwater Institute had the following to say.

“RAS technologies make it possible for fish like salmon to be a local ‘farm-to-table’ option, because they allow the farm to be located just about anywhere. Superior Fresh is giving us a glimpse of the future of sustainable salmon and leafy-green production through the integration of RAS with aquaponics technologies at a commercially relevant scale.”

The greens are grown on floating foam rafts with their roots suspended in nutrient rich water fed into the greenhouse from the fish house. Seedlings are started in a germination room, that are transferred to a propagation room for to 10 days, before being placed in the rafts. The Venlo greenhouse has a completely controlled environment with gas hydronic heating and efficient LED lighting.

The entire facility is highly sustainable. The water flowing from the fish house undergoes fine filtration plus UV light exposure to kill off bacteria. The collected solids will be composted and then applied to a field connected to the facility on which alfalfa is being grown. Offal and other waste from processing the fish will also be land-applied in a similar manner. Likewise, any water overflow, after being purified, is to be fed into an irrigation pond

Chief Operating Officer Brandon Gottsacker is proud that the facility is located on a farm, rather than an industrial park. In fact, it is part of a larger land reclamation project called North Country Clear Waters, where invasive plant species have been removed and over 60 acres have been converted back to native wildflowers.

Says Gottsacker,

“You can see what’s happening to our streams, rivers and specifically the Gulf of Mexico. Our current agriculture is inefficient, unsustainable, and is contributing to major water issues throughout the globe. We look at global warming, and obviously, there are significant changes to our climate taking place. We are seeing severe consequences such as droughts out West, where 90 percent of our leafy greens are grown. Why are we shipping food all over the country, when we have the ability to grow it locally? We’re not gaining more land, so we need to keep coming up with solutions to growing more food on less land. We definitely feel like we’re on the cutting edge here.”

The fish have been blind taste-tested by a panel of chefs and found to be excellent. They are highly nutritious as well, with high levels of omega-3, and low levels of omega-6. Gottsacker is maintaining an all-natural feed formula that avoids GMO corn or soy meal. They currently qualify for an organic hydroponic designation (though the question of whether hydroponics can be considered organic is currently under review).

Looking at the overall sustainability of raising food this way, we can note several important facts. Growing plants in a greenhouse is thirty times more space efficient than growing in a field, while using twenty times less water. The only water lost in this process is that which is consumed by evapotranspiration. It’s also worth remembering that fish is a very efficient protein source, where one pound of feed produces nearly one pound of fish. That compares favorably with chicken which requires roughly 2.5 pounds of feed per pound, or larger animals like swine or beef, which have conversion ratios as high as six or even twelve to one.

The first tiny fish (fry) will be introduced into the facility in December. They will be transferred to new tanks as smolts and then again as adult salmon. The first salmon harvest is expected in the fall of 2018.

about the author
RP Siegel
Skilled writer. Technology, sustainability, engineering, energy, renewables, solar, wind, poverty, water, food. Studied both English Lit.and Engineering at university level. Inventor.