Zohar’s laboratory starts with water from the same supply that feeds household taps. By adding a precise mix of salts and trace elements, the lab creates its own seawater, which it then monitors and regulates by computer as the seawater cycles through the network of pipes and filters and swimming pool–sized fish tanks that make up this miniature, indoor ocean. Everything about the artificial saltwater—from its temperature, salinity, and pH to its CO2 and oxygen concentrations—can be adjusted, on a tank-by-tank basis, to suit the species of fish and to mimic the changing conditions the fish would experience as they moved through both time and distance in the wild. “The entire system is biosecure,” boasts Zohar. “We don’t take a drop of water out of the harbor and we don’t drain a drop of water into the harbor.” In fact, the lab recycles the same several thousand gallons over and over. Of course, in areas with water shortages, commandeering several thousand gallons of water to set up tanks may not be an option, so this may limit the applicability of this technology.

For Zohar, recirculating aquaculture represents a lifetime of research—each detail a carefully crafted response to the problems associated with existing aquaculture technology. Fish grown in Zohar’s tanks require less food per pound than the same fish grown in a net-pen. The reason for this is simple: Because there are waves, and because salinity can’t be optimized, net-pen fish expend more energy on movement and regulating their internal salt concentrations (osmoregulation) than they otherwise might. On top of that, food in the pens is not completely consumed; a portion of it sinks to the bottom of the pen, where it can’t be recovered or reused. In the RAS setting, by contrast, aquaculturists can control food intake much better; and because salinity is always optimal, fish don’t have to invest as much energy in osmoregulation. As a result, they convert their food into flesh at a much higher ratio.

To further reduce their dependence on smaller marine fish for food, the researchers are experimenting with a variety of alternative feeds. The main contender so far seems to be algae; in a room adjacent to the fish tanks, long plastic tubes—the size, shape, and color of colossal lime green freezepops—hang from thin metal racks. Each one is filled with algae that will eventually be converted into food pellets (along with several other ingredients) and given to the fish. “All of the optimal ingredients in marine fish—the omega-3s, etc.—all come from the base of the food chain,” says Zohar. “So why not feed them algae?”

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To manage the accumulated liquid and solid waste in the RAS systems, Zohar’s team employs carefully calibrated microbial communities that function much like they do in the ocean. One community converts ammonia into nontoxic forms. Other bacteria convert some 96% of the solid waste into fuel-grade methane. “So on top of all the other benefits, the system produces energy, about 10 liters of biogas every day,” Zohar explained on a recent tour of the facility. That’s not enough to power the entire system, he says, but it certainly offsets some of the energy costs. INFOGRAPHIC 31.6

As good as it all sounds, RAS facilities will have to meet a number of challenges before they can possibly hope to replace net-pens. For one thing, net-pens are much cheaper to set up and operate. The technology is simpler—and proven to work—and for fishers used to dealing with water and boats and navigation, growing fish in coastal or offshore net-pens is less of a leap than growing them in warehouses. “Systems like the one Yonathan has developed are definitely more environmentally friendly,” says Juarez. “But in our world, everything comes down to economics. If it’s going to take off, they have to prove it’s profitable.”

In a warehouse on the edge of Baltimore, tucked away from the harbor, Zohar and some business partners are trying to do just that. They’ve rented a 17,000-square-meter (180,000-square-foot) space (that’s seven times larger than the inner harbor lab) where they plan to scaleup operations—from tanks the size of small above-ground pools, to tanks the size of large in-ground pools, and from 2 metric tons of fish per year to 400 metric tons of fish per year. “That’s almost a million fish a year,” says Zohar’s business partner, David Wolf.

While the start-up costs are much higher than they would be for a net-pen facility, RAS comes with its own set of advantages, too. For example, as Zohar and Wolf are quick to point out, the type of fish grown can be chosen based on economic opportunity rather than location. “So you can grow Mediterranean fish in Maryland or Minnesota,” says Wolf. “We could literally raise these fish next to a distribution house in Kansas, and because of that proximity, our fish will be fresher, and probably cheaper, too.”

Right now, roughly 85% of fish consumed in the United States are imported, often from great distances. Not only does that make the fish less fresh and more expensive, it also means the environmental footprint for Mediterranean fish consumed in American restaurants—which includes fossil fuel for transportation and freezing, along with the resultant air pollution—is significant. By reducing the distance between the fishery and the consumer, RAS technology could make that footprint much smaller.

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In an ideal world, aquaculture would provide the vast majority of fish we humans eat, while wild populations—along with the ecosystems they inhabit—were left to recover with only sustainable harvesting of healthy stocks. If RAS facilities prove commercially viable, coastal aquaculture ponds and net-pen farms in developing countries could be scaled back; the mangrove swamps and coastal ecosystems they displaced could be restored; and, just maybe, fish could be produced, both profitably and sustainably, for local markets rather than shipped thousands of miles around the globe.

RAS operations are cropping up around the world, but the start-up costs of an RAS facility make it unlikely to be feasible in poorer regions. Nor will large-scale RAS facilities be a viable option in water-starved regions, where several thousand gallons of freshwater can be difficult to come by. Meanwhile, the loss of net-pen farms, while good for the environment, translates into a loss of income for areas that rely heavily on fish exports. As with many other environmental problems, we must consider the triple bottom line (see Chapter 1) and take steps to address the social and economic issues as well as the environmental ones.

Finally, even if RAS operations can be made cost-effective, and the fish feed problem can be solved, and the fishers retrained, there will still be one more hurdle to clear before fish become as domesticated as chicken. Consumers must accept farmed fish, must come to think of them as no different than, or even better than, those harvested from the ocean. This may be an easier sell in developing countries, where some 2 billion people rely on fish protein for their very survival. But in the United States, where fish protein is still something of a luxury, and where the first RAS facilities are stammering to life, Zohar knows that it will all come down to taste. That’s why, when the first harvest of Mediterranean sea bass was ready, he organized a cook-off at McCormick & Schmick’s Seafood Restaurant. Chefs from five Baltimore restaurants prepared two plates—one using wild-caught fish and one using the fish Zohar had grown in his laboratory fish farm—of five different dishes. The result? “You couldn’t tell them apart,” says Baltimore chef Damon Hersh, who participated in the contest. “They tasted exactly the same.”

Select References:

Dyck, A. J., &Sumaila, U. R. (2010). Economic impact of ocean fish populations in the global fishery. Journal of Bioeconomics, 12(3): 227–243.

FAO Fisheries and Aquaculture Department. (2014). The State of World Fisheries and Aquaculture. Rome: Food and Agriculture Organization of the United Nations.

Krkošek, M., et al. (2007). Declining wild salmon populations in relation to parasites from farm salmon. Science, 318(5857): 1772–1775.

Mason, F. (2002). The Newfoundland cod stock collapse: A review and analysis of social factors. Electronic Green Journal, 1(17). http://escholarship.org/uc/item/19p7z78s

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