October 5, 2022 - Written by: Nancy Pollard
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 Farming Most Foul

As seductive as the idea of open net pen-farming of salmon is, particularly its enticingly cheap start up costs, several serious issues exist that will never be correctly addressed even with money, scientific advances and engineering. Chilean salmon farm from Portal University of Texas websiteThe companies and countries that are using the ocean as their feedlot (feeding a huge number of  fish with pellets made from smaller fish, chemicals, dyes and ‘alternative protein’) extrude a huge amount of feces, dead fish and unconsumed feed on the ocean floor underneath the pens. This creates a creeping environment of harmful algae, which kills off other forms of marine life and reduces the amount of oxygen in the pen area necessary for the fish to survive. 

Additionally, the buildup of marine debris on the nets and mooring appendages is never fully cleaned out, even in the best of circumstances. A new term has evolved – biofouling. It’s a bit more complicated to take care of than, let’s say cleaning out a stable. While biofouling needs to be removed almost weekly to prevent the buildup that contributed to the disaster in the Puget Sound by Cooke Seafood, it currently requires chemicals that are also deleterious to marine and ultimately  human life. As with Teflon, these chemicals will ultimately have to be outlawed for use in the oceans for obvious reasons.

A final issue is two-pronged: the spreading of pathogens from farmed stocks to endangered fish populations and the interbreeding of escaped alien farmed fish with native wildfish populations. Farmed salmon suffer enormously from sea lice, which cling to them from infancy to harvesting. They get doused with a delicing solution and in addition areSalmon wars book cover inoculated with a variety of antibiotics to stave off disease. An interesting side note is that farmed fish have a smaller gene pool structure than wild fish. Their interbreeding, according to Collins and Frantz, the authors of Salmon Wars, creates problems:

Studies have found that hybrid offspring are less able to survive in the wild and that interbreeding constitutes genetic pollution that reduces the evolutionary fitness of the already declining wild population.

Almost any independently researched article that I have read almost screams out that open net pen fish farming should be banned. They produce, in my mind, an artificially low-priced salmon – based on either leased ocean acreage at very cheap prices or, in the case of Chile, the ocean acreage is free. Their companies are not held accountable for removing biofouling debris (the fines we have seen do not cover the recovery costs from the damage done to the maritime area) or pay any sort of  tax on the amount of toxic waste their pens excrete onto the ocean floor.  Clearly, another cleaner technology must be developed and funded to supply the planet with fish. And these open net pen fish farms need to be banned. So far, Argentina is the only country to do so.

Help On The Way?

And yes there is – it is called Recirculatory Aquaculture System or RAS. Its inventors, technicians, engineers and investors hope that this new and evolving technology will upend the current open pen farming system. Briefly, water is recycled and reused through a series of filtration processes both mechanical and biological which remove “suspended matter and metabolites.” RAS is designed for land-based, high density aquaculture, in which the fish swim in tanks in buildings against a strong but regulated current. Water temperature and quality, as well as pathogen control are tightly monitored. In most cases, fresh water for the younger salmon is used and then later sea water tanks are used until the salmon or trout are market ready. Still, two thorny issues remain: how best to return the filtered waste water back to its source and how to feed the fish without using wild small fish stocks, which are important for local economies. 

Start-up costs are high, so that regions in which this technology is evolving have to provide financial incentives, and the companies themselves have to get private investment as well. While several of the RAS fisheries still have waste-water issues, the one currently developed in Wisconsin under the name of Superior Fresh may offer the optimum solution. The water used for raising market-ready fish is then used to hydroponically grow greens. The feed is now made from fish trimmings, oils and poultry trimmings. The authors of Salmon Wars describe it best.

Superior fresh hydroponic greens using RAS Groundwater is pumped into the fish tanks, creating a current for them to swim against. As the water leaves the fish tanks and before it gets to the greenhouse, it undergoes a two-step filtration system. A mechanical filtration device extracts the solid waste, generally feces and feed particles. A biofilter uses beneficial bacteria to break down and remove toxic chemicals like ammonia, resulting in nutrient-rich water that is then recirculated to the greenhouse. The plants absorb the nutrients and clean the water in the process. The clean water is circulated back to the fish house to begin the cycle again.  Any water spilled throughout the process is captured in containment trays, moved to storage ponds, and used on the farm to irrigate alfalfa fields and perennial grasses, which are cut for hay. The organic matter extracted during the mechanical filtration phase is transferred to wetlands where it composts with the other native plants. In other RAS systems, solid waste and water are contaminated by salt water and must be trucked off to landfills or disposed of in other ways. Superior’s systems recycle 99.9 percent of the water and doesn’t even waste the waste, creating a symbiotic ecosystem of fish, crops, and land.

One of the co-founders of Superior Fresh told the authors that for five pounds of  sustainable fish feed, the company gets five pounds of marketable salmon and twenty-five pounds of “organic” greens. (hydroponic vegetables now get the US  Organic certification, a term  that is bitterly contested by organic farming organizations). And this farmed salmon tastes better than the open pen farmed version, according to a tasting panel in New York City and the authors themselves.

Some Consumer Suggestions

Some readers have asked for suggestions as to what to follow for their own seafood purchases. Having looked at severalSeafood Watch Poster from Monerey Bay Aquarium website websites and after reading this book, you can do no better than to follow the Seafood Watch guidelines of the famed Monterey Bay Aquarium. And by following these instructions you can add it to your home screen on your device, 

As far as national grocery store chains go, Whole Foods seafood program is probably the best. It’s not perfect, as Greenpeace will tell you, but at least they are trying to be  sustainable seafood team players.  Our local seafood store MAS  Seafood, is very up-front about where they buy and why, and there is always a nice selection of  wild caught seafood as well. I am somewhat wary of seafood guides from organizations that have a corporation as their funding partner, such as  Sysco or Unilever. Wherever you purchase, be the demanding consumer and ask questions. Sometimes, there is no other choice between wild and the open net- pen farmed fish, but your voice is needed at the fish counter.



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