Farming the deep blue sea
Will offshore aquaculture feed the world or spell environmental trouble? NOAA tests the waters.
In the late 1980s, Neil Sims had a fisheries biologist’s dream job—working on the turquoise waters of the Cook Islands in the South Pacific. But things soured when the season opened for giant clams and pearl oysters. “Despite our best-laid management plans, people rushed out to plunder and pillage,” the native Australian says. One day, Sims spotted an old man in a boat loaded with sacks of oysters.
“Papa,” Sims said, looking them over, “you know you’re not supposed to have these. They’re all undersized and I’m going to have to take them.” Sims says the old man started crying. “Why do you stop this?” he pleaded. “There’s still some left. There’s still some left!”
The old man’s plea summed up for Sims the basic problem with fisheries. People just take too much. Over the last century, humans have become so adept at pulling fish from the oceans—a big ship can catch a ton an hour—that they risk driving many species to extinction.
Today, Sims runs a fish farm in Hawaii called Kona Blue, located in deep waters a half mile offshore. The farm raises a species of Hawaiian yellowtail, and Sims says the company strives for ecological sustainability. He thinks farming the oceans, instead of chasing down wild fish, is the only sustainable way to meet the world’s rising demand for seafood.
Others have their doubts. Citing pollution and disease troubles, they call fish farms “the feedlots of the sea”. Either way, the U.S. is poised to join a growing number of countries in a grand experiment, farming earth’s last great frontier—the open ocean.
On April 24, Rep. Nick Rahall (D-WV) introduced a bill in Congress that would dramatically expand ocean farming. For now, farms like Kona Blue are only permitted in state waters in the U.S., within 3 miles of shore. The National Offshore Aquaculture Act would allow the government to lease patches of now-protected ocean to private companies to operate fish farms. The bill, backed by the National Oceanic and Atmospheric Administration (NOAA), would expand the area for farming to include the U.S. Exclusive Economic Zone, between 3 and 200 miles from shore. The U.S. now imports 80% of its seafood from other countries, NOAA points out, and those countries are propping up their own fisheries through aquaculture, or fish farming—mostly in big tanks or in ocean pens along the shore.
Around the world, stronger cages and high demand are allowing farms to push farther and farther from land, braving currents and storms to grow the kind of big, mostly carnivorous fish that command top dollar. Red snapper, halibut, cod, and yellowtail are among the fish now farmed in U.S. research and demonstration projects. Many more species are farmed around the world, including bluefin tuna that are caught when young and fattened up in floating ranches.
Critics such as environmental groups and some ocean researchers and public-health advocates fear that the new offshore industry will repeat the mistakes of some nearshore farms. How can farms be sustainable, they ask, when wild fish are caught to make food for the farmed fish? And other problems have been pointed out, including pollution and disease outbreaks that ravage overcrowded fish in floating nets.
Feeding the multitude
There’s a fundamental problem keeping the idea of ocean farms afloat. Demand for fish is soaring worldwide, both in well-off countries like the U.S., where sushi and healthy fish fats are in vogue, and in poorer countries like Tanzania, where even cast-off heads and tails provide food. Worldwide, about 1 billion people rely on fish as their main source of animal protein. And the world will need to come up with an additional 40 million tons of seafood per year by 2030, NOAA estimates. But wild catches have leveled off and are widely considered unsustainable.
To many people, farming looks like the only solution. And the aquaculture industry is growing fast to meet the demand. Globally, farmed fish production more than doubled from 1987 to 1997. The industry is growing at 9% per year—about the same rate as China’s booming economy.
But experts argue about whether fish farms can really fill the gap. Rosamond Naylor, a Stanford University economist who studies intensive food production, argues that the math doesn’t add up. For each pound of farmed fish that’s grown, she writes, 2–5 pounds of other fish must be caught and used as feed. Other researchers come up with different numbers, but most agree that farming carnivorous fish currently consumes more fish protein than it produces.
The problem is the feed. Most farmed ocean fish are carnivores, and their chow is made from a blend of grains and small fish like anchovies and sardines, ground up into pellets. These smaller fish are important links in the marine food chain, and Naylor and others are concerned that farming will add pressure to an already stressed ecosystem.
Dan Benetti disagrees. He directs the aquaculture program at the University of Miami and has spent the past 20 years developing aquaculture practices. He’s also a strong supporter of NOAA’s offshore plan as described in the legislation. “A lot of people are saying we need to feed small fish directly to people,” Benetti says, but he disagrees with that. People only eat about 45% of most fish, he says. The rest—the head, tail, and bones—is usually thrown away. “If we take 100% of that fish and transform it to a pellet with cheap fillers like soy and feed it to fish, the yield is higher.” Currently, most fish meal goes to feed land animals like cattle and hogs, he adds, which are even less efficient than fish in terms of production.
As for the claim by some scientists that it takes as much as 6.6 pounds of wild fish to produce 1 pound of farmed fish, “our work showed that the average from industry was between 1.6 and 3.5,” Benetti says. “So it’s much more efficient than what’s reported.” Plus, he points out that aquaculture companies are developing new feeds based increasingly on vegetable proteins. Other supporters emphasize that fish farming is probably more efficient than fishing, because farmed fish are protected from predators, and therefore few are lost. Farming also avoids the problem of bycatch, fish caught unintentionally that are often thrown dead or dying back into the ocean.
For now, however, it’s not clear that marine farming is replacing the hunt for wild fish. Between a quarter and a third of the world’s harvested fish are converted to animal feed each year, millions of tons of which go to feed farmed fish.
There’s always a catch
Other high-profile problems in coastal farms have made people wary of expansion. As fish farms grow bigger and bigger, pollution and contaminants can become a problem, escapees pose potential threats to wild populations, and disease outbreaks ravage fish crowded fin-to-fin in floating nets.
One outbreak recently hit salmon farms in Chile with the force of a plague. Swimming parasites called sea lice, a kind of copepod, have been a problem in coastal farms for years. The lice attach to fish in droves, living in the mucus on their skin and creating lesions that can get infected or disturb salt–water balance.
During the past few months, one such outbreak spiraled out of control. Temperatures climbed and salinity rose in the absence of rain during the South American summer (December through February), says Sandra Bravo, a researcher at the Universidad Austral de Chile who studies sea lice. This created perfect conditions for sea lice to multiply.
After years of constant use, the pesticide stopped working. As the sea lice got worse, farmers used more, and they topped it off with antibiotics to control infection of the fish’s wounds. Over generations, the lice had become resistant to Slice, “which caused the multiplication of this parasite without control,” Bravo says. After a long and losing arms race against the lice, farmers resorted to abandoning some farms and transporting their remaining fish by boat or helicopter to louse-free waters.
In 1998, Schering-Plough introduced a pesticide to control sea lice, emamectin benzoate, with the brand name Slice. For more than 7 years, it was the only sea-lice treatment approved by the Chilean government, Bravo says. Having only one treatment option was the root of the problem.
Sea lice mainly attack salmon and trout, but other diseases and parasites can affect any species kept in tight quarters, Benetti says. And the feared spread of disease from farmed to wild fish has been hotly contested. Last year, research showed that migrating salmon pick up lice as they pass farms. Some in the industry adamantly deny a problem.
“For the last 25 years, we have seen documented evidence of problems at salmon farms, and we see no evidence of fixes for the problems of escapes and sea lice,” says Andrea Kavanagh of the advocacy group Pure Salmon Campaign, a project of the National Environmental Trust. The group advocates replacing net cages with enclosed tanks with more controlled conditions, a practice used now at land-based farms but one that is not currently part of the NOAA plan.
Fish farms face another basic problem: fish can swim. “It’s not like we’re dealing with domesticated chickens. If chickens get out of a Perdue factory, they don’t last long,” says Rebecca Goldburg of Environmental Defense. Fish that wriggle out of nets can get established and change the local gene pool, she says.
In April, the Norwegian Directorate of Fisheries released data (here in English) showing that more than 1 million fish escaped from the country’s commercial farms in 2006. Now the country, which has been a leader in the aquaculture industry, is considering policy changes to reduce the number of escapees.
Plus, the salmon industry is already working on genetically modified (GM) fish that grow bigger and faster. Even though none are on the market yet, environmental groups are worried. Under NOAA’s plan, GM fish wouldn’t be allowed, unless “a scientific risk analysis shows that the risk of harm is negligible or can be effectively mitigated.” Goldburg asks how farmers will know the harm is negligible without running an oceanic experiment that could backfire.
Pollution is an issue, too. First, there’s the accumulation of contaminants in farmed fish. Feed containing small wild-caught fish also contains the pollutants in those fish, and they accumulate up the food chain. Because farmed fish eat only their pellets instead of the wider variety of food that wild fish encounter, they could be getting a larger dose.
Farmed salmon, grown mostly in coastal waters, have drawn the most fire. Research has shown higher levels of contaminants such as PCBs in farmed salmon compared with wild salmon, although scientists disagree about whether these results are representative of all farmed fish.
Another pollution problem is the waste produced when thousands of fish eat and excrete together in a small patch of the sea. A study by Goldburg and Naylor calculated that developing a $5 billion offshore aquaculture industry, which NOAA has set as a goal, would dump into the ocean the nitrogen equivalent of untreated sewage from more than 17 million people every year, or about the amount of nitrogen in annual waste from North Carolina’s hog industry. At 100,000–150,000 metric tons of nitrogen per year, a $5 billion U.S. offshore industry would release about a tenth of the nitrogen that the Mississippi River pours into the Gulf of Mexico annually, but would distribute it across a much larger area.
Proponents say the solution lies beneath the waves. Farther from shore, strong currents could sweep wastes away. And some projects have shown that careful feeding and monitoring can prevent wastes from building up below and around cages. An example is Hawaii’s demonstration project that became the commercial farm Cates International—monitoring data show that nutrients drop off to background levels within 300 feet of the cages. Kona Blue also has demonstrated good water quality around its operation. Environmentalists worry, though, that some farms won’t act responsibly and that large farms will cluster together.
Benetti goes a step further, turning the pollution argument on its head. In coastal areas, he say, farms do pollute, adding to nutrient levels that are already too high in some areas. But in the open ocean, where background nutrients are low, he says farms “can be seen not as point sources of pollution but as point sources of fertilization.” He adds, “Fertilization could enhance the production of small pelagic fish, which could be caught and used to sustain the larger fish, making the whole process neutral or environmentally sustainable.”
Benetti’s idea is echoed by Clifford Goudey, an engineer at the Massachusetts Institute of Technology who designs aquaculture systems. “I was diving down to cages at Snapperfarm, [a commercial farm] in Puerto Rico, and there was a little ecosystem around the cages,” he says. “You get an increase in abundance of sea life around the cages, and by most people’s standards that’s an improvement. It’s not a desert like people imagine.”
Red, white, and blue water farming
The U.S. may not be short on food supplies, but it has a growing appetite for the sea’s bounty. Americans eat nearly 7 million tons of seafood per year now, and sales of domestic farm-raised seafood grew nearly 12% over the past 7 years. Not only is the U.S. relying on imports for most of that seafood, but it’s also missing out economically, NOAA says, to the tune of an $8 billion annual trade deficit. So the agency wants to tap into an aquaculture market that’s dominated by China, which turns out 70% of the world’s farmed seafood.
NOAA first proposed to farm U.S. oceans in 2005, with a bill that sank in Congress after environmental groups attacked its weak marine protection. That sent the agency back to the drawing board. It set up a blue-ribbon task force, sponsored by Woods Hole Oceanographic Institution and the Pew Oceans Commission, to recommend how to develop offshore aquaculture without damaging the environment.
“Of nine members, I was the lone representative of an environmental organization” on the task force, says Environmental Defense’s Goldburg. She says the new bill incorporated some of the group’s recommendations, like requiring the administration to establish environmental requirements, but it is “still inadequate” in her estimation.
The latest version of the bill still draws fire in part because of its vague language about environmental requirements. According to the bill’s language, NOAA must only “address” (not minimize) environmental impacts, for example. Another sticking point is that environmental groups don’t trust the U.S. Department of Commerce (which oversees NOAA) to do a good job of setting up a system to regulate fish farms. Those regulations would be put in place after the bill passes.
The new bill is swimming upstream in Congress, against a tide of wartime funding battles and an impending presidential election. Even the bill’s sponsor says that he doesn’t necessarily support it. “We must be very careful that offshore aquaculture does not further jeopardize the health of our oceans in any way,” Rahall added when he introduced the bill.
But if the bill fails again this time around, no one, particularly NOAA officials, thinks that offshore aquaculture is going away. The agency is already pouring $20 million a year into research and demonstration projects like a farm in the Gulf of Mexico, and the legislation ranks high among the agency’s priorities. “I think this is something the U.S. can do, should do, and is way behind on,” says NOAA Fisheries Service director Bill Hogarth.
