The Trouble with Aquaculture

Whether fish is farmed or caught free, the process of getting delicious seafood onto the plates of consumers is rife with problems. Open sea fishing has severely depleted wild fish stocks, and as a result, roughly half of the seafood sold in the United States is farm raised, rather than caught in the open waters, according to NPR. But like most commercial agriculture, the aquaculture (fish farming) industry struggles with problems of inefficiency and environmental impact. The practice of confining thousands of fish to relatively small pens makes it necessary to use pesticides and antibiotics to prevent the spread of disease. Since aquaculture facilities are usually located in the ocean, discharges of fish waste, cage materials, and pesticide chemicals can damage surrounding ecosystems and threaten wild fish populations. Escapement is also a problem, as escaped fish from these facilities compete with native populations for food.

Furthermore, fish need to be fed, and the question of how to feed farm-raised fish presents yet another challenge, particularly when it comes to carnivorous species such as salmon and tuna. As Food & Water watch points out, farmed fish are often fed with wild species such as krill, with the effect of further threatening wild fish populations by depleting vital elements of our oceans' ecosystems. It's a system that's woefully inefficient: to raise one pound of farmed tuna, for example, 15 pounds of wild fish are converted to feed, according to chef Dan Barber -- wild fish, some argue, that could be used to feed humans instead.

In a 2010 TED Talk, Barber described his attempts to find a source of fish that were both delicious and ecologically sustainable. It seemed that even the best intentioned farms relied on questionable practices. Barber relates the story of one company that boasted a 2.5 to one feed conversion ratio -- i.e. 2.5 pounds of wild fish to every pound of farmed fished. Not ideal, but certainly better than the aforementioned 15 to one ratio. What disturbed Barber, however, was the discovery that a full 30 percent of the fish feed was composed of chicken products, prompting Barber to ask, “[W]hat's sustainable about feeding chicken to fish?”

“It takes fifteen pounds of wild fish to get you one pound of farm tuna. Not very sustainable. It doesn’t taste very good either.”
— Barber. (2010, February 12). Dan Barber: How I fell in love with a fish

The challenges of finding environmentally sound ways to meet consumer demand for seafood place chefs like Barber and ecologically-conscious consumers in a difficult bind; it would almost seem as though the only solution is to abstain from seafood altogether until natural stocks have been replenished to sustainable fishing levels, a process that could span generations. But given the popularity of seafood and the recent USDA recommendation that Americans make seafood their meal's main protein at least twice a week, such an initiative seems unlikely to occur any time soon.

Ecological Engineering

Barber's quest to find a sustainable source of fresh, delicious seafood eventually introduced him to Veta la Palma. Located in the Spanish municipality of Puebla del Rio along the Guadalquivir River, Veta la Palma is less a farm than it is a teeming ecosystem, using both artificial and natural means to foster conditions under which a diverse array of species, both native and farmed, thrive. Sea bass, sea bream, shrimp, sole, mullet, and eels are among the varieties raised in Veta la Palma's 8,000 plus acres of interconnected ponds, which are maintained at varying degrees of salinity.

Artificial means such as hydraulics play an important role in maintaining optimal conditions at Veta la Palma, but the farm's biggest asset is arguably the natural marshland in which it's located. After decades in which the land's previous operators attempted to drain the surrounding wetlands, the proprietors of Veta la Palma used the previously dug canals to flood the area. The farm's website frequently refers to its artificially flooded ponds and wetlands, but one could just as easily make the argument that these features have simply been restored to their natural state.

Methods used at Veta la Palma work to promote the health of the marshland's native ecosystems, which includes populations of plankton, algae, crustaceans, and other aquatic invertebrae. It's these organisms, rather than processed meal or chicken pellets, that sustain the fish raised on Veta la Palma, eliminating the need for outside feed sources. These organisms also serve as natural filtration systems by absorbing both nutrients from fish waste and contaminants from the local water source. The result is a farm that raises a variety of delicious, organically fed fish without polluting surrounding habitats; on the contrary, water circulated through Veta la Palma is returned to the Guadalquivir River cleaner than when it entered.

The contained nature of the ponds at Veta la Palma allow the farm to take advantage of the surrounding ecosystems while maintaining a level of control that would be impossible to achieve in the open ocean. Its a scenario that's heavily dependent on location and therefore difficult to replicate. But the premise of engineering entire ecosystems to support aquaculture offers some promising possibilities.

Since the 1980s, natural advantages such as high tides and sheltered coastlines have made Canada's Bay of Fundy an increasingly popular site for aquaculture, particularly among Atlantic salmon farmers. But the farms, now an integral part of the local economy, have met resistance from environmentalists and fishermen alike, who contend that waste and escapes from the bay's farms, like their open-ocean counterparts, damage the native ecosystem and threaten wild populations of fish and shellfish.

In June, NPR's Richard Harris reported on a new type of salmon farm in the bay, a partnership between Cooke Aquaculture and researcher Thierry Chopin. The facility uses a method called integrated multi-trophic aquaculture (IMTA) in an attempt to increase the farm's long-term sustainability. Unlike traditional salmon farms, this farm cultivates species of seaweed and shellfish alongside its salmon. Not only do these organisms help offset the waste produced by salmon, they are also commodities unto themselves. Kelp grown in the bay is used both in food and in cosmetics; the commercial applications of the farm's mussels are fairly self-explanatory.

Chopin estimates his approach will reduce pollution produced by the farm by anywhere from 10 to 50 percent. In his conversation with Harris, Chopin discusses plans to introduce organisms such as sea urchins, sea cucumbers, and sea worms to help offset waste even further. Chopin also says he is experimenting with seaweed-based fish food in the hopes of addressing the feed ratio problem.

Inland Operations and Aquaponics

Efforts to make aquaculture less polluting and more sustainable have taken some fish farms inland. By raising fish in land-locked, man-made enclosures as opposed to deep sea pens, fish farmers can avoid many of the problems associated with open ocean aquaculture, such as escapement and the spread of disease to native fish populations. Moreover, the isolated conditions in which inland fish are raised drastically reduce the need for antibiotics and other chemicals that would otherwise be necessary to control parasites and disease. Fewer chemicals means less pollution and fewer consumer health concerns.

Still, critics of inland fish farms have pointed to high energy consumption, excessive water usage, and continued concerns about waste treatment and disposal as arguments against such facilities. Most traditional fisheries, meanwhile, are unlikely to head ashore any time soon due to the comparatively high costs of operating inland farms. Whereas in traditional deep-sea fish farms water, circulation, and waste removal are provided for free courtesy of the ocean, inland farmers have to shoulder those burdens themselves.

A few farms, however, have made significant strides in addressing both the economic and environmental concerns associated with inland fish farming. In March, the Vancouver Sun reported on the harvest of the first ever inland-raised sockeye salmon to be produced for commercial consumption. The facility, located in Langley of British Columbia and operated by Willowfield Enterprises, is able to reduce both costs and environmental impact by taking the self-contained nature of inland fish farms and combining it with nearby natural resources. Water circulation is achieved by drawing water from a nearby spring and allowing it to flow through several ponds, beginning with the artificial salmon tanks and continuing on through several native trout ponds whose plant life acts as a natural filter. Any solid waste remaining once the water has passed through the trout ponds is removed and used as a fertilizer by a local farmer. The water -- which has been tested and certified as non-polluting, according to Willofield Enterprises president Don Read -- is then returned to a nearby creek.

Like Veta la Palma, the Willowfield Enterprises facility in Langley takes advantage of the native ecosystems that surround it. But for inland aquaculture facilities that don't have access to such optimal conditions, aquaponic farming methods offer a new approach to maximizing efficiency and productivity while minimizing environmental impact.

Aquaponic farming takes the already efficient methods used in hydroponics, a growing technique wherein produce is grown directly in water rather than soil, and adds fish to the equation. Fish and plants form a symbiotic relationship wherein nitrogen-rich fish waste serves as fertilizer for the plants, which  in turn filter water in which the fish live, creating a closed loop system that drastically reduces the need for water changes or outside fertilizers. Here, the advantages of raising fish in a controlled environment apply to produce as well; because these operations typically take place indoors, crops can be raised organically and without being limited by the changing seasons.

For now, aquaponic growing systems are typically marketed for domestic rather than commercial use, but a few farms around the country are endeavoring to prove that aquaponic farming can be a profitable commercial venture as well. One of the most impressive examples of aquaponic farming can be found at The Plant, a former meatpacking plant turned urban farm and sustainable business complex in Chicago. The Plant's aquaponic farm currently occupies about 700 of the building's 93,500 square feet, though the organization ultimately plans to devote a full one third of the building to aquaponic farming. And because The Plant's ultimate vision is to create a business complex that's completely self-sustaining, farming operations go beyond the inherent efficiency of aquaponics; the feed question, for example, will be addressed by feeding fish spent barley generated by a neighboring brewery. Power to the farm's lighting and circulation system -- and, indeed, the entire building -- will be supplied by The Plant's anaerobic digester.

The Plant, of course, is the exception rather than the rule. Most aquaponic operations, commercial or otherwise, still require some energy consumption to keep the lights on and keep water circulating. Vertical farming methods, loosely defined as making use of available space by farming floor to ceiling, can reduce costs and energy consumption somewhat by using gravity to aid water circulation.

Moreover, there are limitations to what can be grown and raised using aquaponics. For example, in order to support healthy produce, aquaculture operations on aquaponic farms are limited to fresh water fish. Tilapia, the fish of choice at The Plant, do well in crowded conditions and tolerate temperature fluctuations, though The Plant notes that it has plans to add prawns to the equation in the near future. As vegetarians and bottom-feeders, the feed ratio for these species is a non-issue; sustainable cultivation of carnivorous fish such as salmon or tuna is a much more difficult undertaking.

Consumer Action

It goes without saying that the innovations found on farms like Veta la Palma, Cooke Aquaculture's Bay of Fundy facility, Willowfield Enterprise's Langley facility, and The Plant make up a minority of the seafood market share; the vast majority of seafood consumed in the United States is still fished or farmed under less than ideal circumstances. Given the rarity of sustainably farmed fish, it's no surprise that even the most conscientious consumers can have difficulty making healthy, eco-friendly seafood purchases. Particularly enterprising individuals with the space, time, and capital can experiment with aquaponics in their homes, but for the rest of us the options are more limited.

Local farmers' markets that include meat, dairy, and seafood vendors provide an excellent opportunity for consumers to learn about a farm's practices directly from the source. For trips to the supermarket, David Zinczenko and Matt Goulding, authors of the Eat This, Not That series, offer some great tips on how make smart seafood choices in their article Fish You Should Never Eat.

Additional Sources:

Bay of Fundy Ecosystem Partnership: Farming Fundy's Fishes

NPR: Can Salmon Farming Be Sustainable? Maybe, If You Head Inland

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In Search of Sustainable Seafood: Emerging Solutions to Fish Farming Woes by UrbanSculpt Staff Writer Leslie McIntyre is licensed under a Creative Commons Attribution 3.0 Unported License.
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