When I wrote about "Mission Blue," the new Netflix documentary about Sylvia Earle, I learned that the famed oceanographer and activist no longer eats fish of any kind. 

"We should think of fish primarily as wildlife," says Earle, "Not food."

Given the devastating impact of overfishing, Earle may have a point. As Jane Brody noted in the New York Times recently, even if we shift our focus to more resilient wild species, the demand for fish is growing so fast worldwide that we will still need to find alternatives to fishing for sourcing a large portion of our fish. With nutritionists advising us to eat more fish as a healthy alternative to meat, and with significant environmental concerns around land-based animal agriculture, is there any way for us to have our fishcake and eat it too? 

The answer, according to some experts, may lie in aquaculture. For those of us who have been paying attention to food sustainability issues, that concept may be surprising at first. After all, from spreading diseases to wild fish stocks to using vast quantities of lesser fish like anchovies as feedstocks for the farmed "crop," environmentalists have been warning about the environmental dangers of large-scale fish farming for decades.

An interesting article over at NPR, however, looks at how high-tech, indoor fish factories may help to meet growing demand and to avoid the pollution and disease issues of conventional fish farming, as well as the depletion and scarcity issues of eating wild stock.

Here's how Yoni Zohar of the Institute of Marine and Environmental Technology in Baltimore, who is growing rare marine species in vast indoor tanks at his laboratory, explained the proposition to NPR:

"The idea is to have the entire life cycle in completely clean and controlled conditions that are disease-free, so you don't introduce anything from the outside," Zohar says. As a result, these fish never need antibiotics, hormones or other chemicals to keep them healthy. And because they are kept in optimal conditions, they grow twice as quickly as fish in traditional net pens in the Mediterranean.
This last point touches on one of the biggest arguments for fish farming, not just as an alternative to wild fishing, but as an alternative to land-based meat production too. Because fish are cold-blooded, and live their entire lifecycle surrounded by water, they require vastly fewer calories to sustain themselves and grow than warm blooded mammals like cattle do. And fewer calories mean less feedstock. Of course what we use as feedstock is as important as how much we use. So if we're still hauling in wild fish to feed our farmed fish, the sustainability argument becomes a hard one to make. That's why Zohar and other fish farmers are experimenting with feedstocks that require fewer or no wild fish, synthesized primarily from grains, algae and an amino acid. 

Besides environmental sustainability, the other challenge for fish farmers is commercial viability. With labor costs in the United States high, competing with low-priced farmed imports from China and South America can be a challenge. But mechanization of processing may, says NPR, help level the playing field. If fuel and shipping costs were to go up in the future, and if countries like China start to get serious about imposing costs on polluters, locating fish farms closer to centers of consumption may start to make a lot of sense. 

Some operations, like Florida-based Green Sky Growers (shown in the video below), is taking this proposition to extremes, growing Tilapia on a rooftop greenhouse farm that recycles the nutrient-rich waste water from the fishtanks and uses it to irrigate and fertilize vegetable crops. The sustainability of this "aquaponic" operation is such, say Green Sky Growers, that they can grow 1 pound of tilapia on about 1.5 pounds of feed — and that's not including the added benefit of "free" fertilizer for the plants. 

The commercial viability of any of these sustainable fish farming operations will depend on several factors that are outside farmers' immediate control. These include fuel prices, the cost of labor, available technology, and the regulation (or lack of regulation) surrounding their wild fishing and conventional aquaculture-focused competitors. But consumers can do their part by seeking out only responsibly caught fish from sustainable fish stocks and sustainably farmed fish from dependable, preferably local aquaculture operations.

Check out the Marine Stewardship Council and Monterey Bay Aquarium's Seafood Watch for information about which fish you can responsibly eat, and learn how retailers like Whole Foods are seeking to promote sustainable aquaculture standards

And don't forget, of course, to support marine conservation as a major priority too.

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