Demand for salmon is soaring and is driving expansion of aquaculture—fish farming. For years, environmentalists advised conscientious consumers to avoid farmed salmon, but that's starting to change, thanks to an evolving industry.

Rich in protein and heart-healthy omega-3 fatty acids and low in saturated fats, salmon is increasingly being marketed as a healthy food. Demand for salmon has risen more than 20 percent in the last decade. Consumption is three times what it was in 1980.

That voracious appetite is increasingly being supplied by aquaculture, which now provides 70 percent of the global salmon market (2.4 million metric tons). In 2013, the largest market for farmed salmon, the United States, consumed 353,000 tons of the fish.

About five years ago, global aquaculture production surpassed wild catches as the primary source of all seafood consumed. Two years ago, global aquaculture production passed global beef production.

Over the past decade, many environmentalists advised consumers not to buy farmed salmon. The carnivorous fish are fed animal-derived proteins, typically supplied as "fish meal" or fish oil made from other species, especially anchovies. Because it can take four or five pounds of fish meal to yield one pound of salmon flesh, the inefficiency caused concern among environmentalists.

Plus, farmed salmon are sometimes able to escape from the oceanside pens they are raised in, potentially spreading disease or undesirable genes to wild populations already under stress from overfishing, pollution, and habitat loss. Fish feed has also been shown to have been contaminated with PCBs and other toxins that can make their way into the food supply.

An Industry Evolves

But the salmon-farming industry has progressed in cleaning up its act, said Jason Clay, WWF's senior vice president for market transformation. Clay, who participated on a panel on farmed salmon at Seafood Expo North America in Boston on Tuesday, started discussions with leading salmon growers in 2002 called the "Salmon Aquaculture Dialogues." Those talks eventually led to the development of a set of sustainability standards called the Aquaculture Stewardship Council (ASC) in 2010.

"There was never really disagreement about what the impacts [of salmon farming] were; the issues that came up were, What is acceptable impact and what is possible to achieve?" he said. "It took eight years to get those standards written up."

The Aquaculture Stewardship Council is an independent nonprofit organization based in the Netherlands. Founded by WWF and the Dutch Sustainable Trade Initiative, it maintains a yardstick against which aquaculture growers can be measured in terms of their social and environmental impacts. So far, a small percentage of salmon grown on farms in Norway has been shown to meet the group's standards, but much more is on the way in various countries, says Clay.

In August 2013, 15 large salmon farm companies, representing 70 percent of the world farmed salmon market, joined together to form the Global Salmon Initiative (GSI). The companies pledged to source 100 percent of their salmon from farms that meet ASC standards by 2020.

Those standards include 152 different indicators, says Clay, including low tolerance for escaping fish, limits on antibiotics, a prohibition on genetic engineering, and sustainability and safety guidelines on food the fish can be fed.

View Images In January 2011, Scotland began exporting farmed salmon to Asia for the first time. PHOTOGRAPH BY JEFF J. MITCHELL, GETTY IMAGES

What's the Food Ratio?

At the World Ocean Summit in Half Moon Bay, California, in late February, Andrew Sharpless, the CEO of the advocacy group Oceana, said, "Aquaculture comes in three flavors: good, bad, and indifferent."

"If you are farming a filter feeder like a clam or oyster, you are doing something tremendously good for the planet: You are cleaning the ocean and filtering something people don't want to eat, algae," said Sharpless. If you are farming fish that feed on plants humans consume, such as tilapia or catfish, "your contribution is about equal to being a chicken farmer and putting it underwater. Could be worse, could be better," said Sharpless, referring to the fact that large-scale chicken farming requires massive amounts of grain.

"If you are farming fish that eat fish, you are reducing the amount of fish available for humans to eat. Farmed salmon are dreadful for feeding people and for protecting ocean health, though they might make good business sense," said Sharpless.

But Clay disagrees. He says those calculations are based on old data, when it took three or four pounds of wild-caught bait fish, ground up as fish meal, to produce one pound of sellable salmon. The target in the new ASC guidelines is a ratio of 1.4, or about half of what the industry was doing overall in 2000, says Clay.

Furthermore, Clay says the accounting is a little more complex. About half of a farmed salmon's mass is currently not used for food, but much of that can be repurposed as feed for another farmed species, such as shrimp or trout, he says. That should be taken into consideration when counting protein ratios.

"Getting to a ratio of one to one is the goal, but it's just not going to happen in a year," says Clay. "We're below two already, and we went from four to two in the last 15 or 20 years so we are on the right trajectory. We have to keep working on it instead of saying, 'It's not good enough and it's not going to be.'"

The key, says Clay, is to ensure that any wild-caught fish that is processed into meal is sustainably harvested, something that is addressed in the ASC standards.

For their part, the GSI argues that salmon farming is likely to play an important role in feeding the world. Avrim Lazar, a Canada-based consultant with the GSI and another speaker on the panel in Boston, says the middle class will increase in coming years. "They are all going to ask for animal protein, whether anyone likes it or not, so it's going to be produced. Our job is to do that with a minimal footprint," says Lazar.

Doris Soto, the senior aquaculture officer for the Food and Agriculture Organization (FAO) of the United Nations in Rome, says, "It's important to remember that there is no free meal; all industries have an environmental cost."

Lazar adds that the driving force behind the industry going greener has not been consumer pressure, since only a small number of people specifically ask for sustainable salmon. "There is huge market demand for any kind of salmon, and changes are driven less by immediate market pressure and more by a sense that if you want to operate in the oceans you need a social license," says Lazar, referring to the fact that the public has a stake in what happens in the ocean.

"Governments and communities have had the question of whether [salmon farming] is a legitimate use of the ocean."

Soto calls the ocean "common property." Fish farming is "not just like a farm on land, so you have responsibilities," she says.

Lazar says the relative newness of salmon aquaculture as a global business provides an "opportunity to get things right at the early phases." Although carp have been raised in Asia for many centuries, the current industry is relatively "very young," he says. Therefore, growers are trying to "lay down wiring and figure out how they should behave," he says.

Soto adds that best practices developed by GSI members are being shared with developing countries, particularly in places like Africa, where there is keen interest in starting aquaculture businesses.

View Images John MacLeod, the site manager at Scottish Sea Farms, holds up a salmon. PHOTOGRAPH BY JEFF J. MITCHELL, GETTY IMAGES

Alternate Farming Methods?

Clay says there has been a lot of experimentation when it comes to salmon aquaculture. Some test sites in Norway have tried raising salmon without feeding them any fish, using other proteins instead. "The price has not yet been acceptable in the marketplace," says Clay.

On Chile's Patagonian coast, DuPont is growing salmon in a different way through a new subsidiary called Verlasso. DuPont engineers in a lab in Iowa developed transgenic yeast that make omega-3s, a desirable compound that salmon don't make themselves but normally get from their food.

The yeast is then blended into feed pellets, taking up about 10 percent of the bulk. The rest is made from plant material and other nutrients, including some fish meal and oil. But because the company uses about a quarter as much fish oil as its competitors do, it has gotten the fish input ratio down to one to one, says Scott Nichols, the Delaware-based president of Verlasso.

"Raising salmon on [three to four parts of fish] is inherently unsustainable," says Nichols. "It doesn't meet the goal of having fish in the future, and it doesn't result in net production of fish."

Nichols says Verlasso raises salmon in pens at a density not to exceed 12 kilograms of fish per cubic meter of water. The industry norm is 25 kilograms per cubic meter, he says.

"So we address two issues: Our environmental load is lower because we don't increase the number of pens as we decrease density. Our fish have more room to swim, they're more active, so they have a different flavor and texture, one most people find very agreeable."

Nichols says his salmon have a fat content of around 11 percent, compared with 8 percent for wild salmon and 17 to 22 percent for "traditionally farmed salmon."

In recognition of Verlasso's progress on key environmental issues, the Monterey Bay Aquarium recently recognized the company's salmon as a "good alternative" in its influential Seafood Watch program, the first time ocean-raised salmon has been so designated. The fish are available at a number of restaurants and grocery stores in the U.S.

Genetically Engineered Fish?

Some boosters say the next step in salmon farming is genetically engineering the fish themselves. Massachusetts-based AquaBounty Technologies has spent several years developing a fish it calls AquAdvantage salmon. The company hopes to raise sterile Atlantic salmon females that can grow to market size in half the time of conventional salmon, thanks to a growth hormone–regulating gene from Chinook salmon and some genetic material from ocean pout.

AquaBounty first submitted data to the Food and Drug Administration for review in 1996 and has been raising generations of the experimental fish in closed pools in the Panamanian highlands. The FDA has yet to approve the fish, which was the first genetically engineered animal introduced into the food supply.

A decision on the fish is still pending. In September 2010, an FDA advisory panel said that the fish is "highly unlikely to cause any significant effects on the environment" and that it is "as safe as food from conventional Atlantic salmon," although the agency said more testing was needed. Still, the company has reportedly had financial difficulties.

No genetically modified salmon are currently permitted under the ASC guidelines. In a position statement, the Sierra Club said it opposes genetically engineered fish, arguing that the fish pose "an even greater hazard to natural stocks and are even more difficult to properly evaluate and to monitor than [genetically engineered] crops."

Even fish in inland ponds can be swept away by floods or transported by birds, says the Sierra Club.

In the meantime, there are signs that farmed salmon is getting leaner and greener, Clay says.