ON THE HEELS OF INDUSTRIAL AGRICULTURE’S “Green Revolution,” international development advocates began promoting fish farming as an alternative food source. The “Blue Revolution,” they argued, would solve the global hunger crisis without deleterious impacts. But as the aquaculture industry has developed, so too have its side effects: water pollution, declining wild fish populations, habitat degradation, and inefficient use of resources. In fact, many industrial fish and shrimp farms resemble floating CAFOs.
Imagine a hog farm floating out at sea. Hundreds of thousands of animals crammed together on the open ocean, heaps of waste riddled with feces and antibiotics drifting off with the current. With certain types of aquaculture, this imaginary scene is not far from reality. What many eaters may not realize as they dine on grilled farmed salmon or pen-raised, pan-seared tuna is that modern aquaculture’s ecological impacts are potentially tantamount to the destruction caused by land-based factory farms.
Critics claim that industrially farmed fish are a decadent luxury that comes with grave ecological costs to our oceans. Rather than supplementing—and maybe even eventually replacing—wild fisheries as the seafood of choice, some segments of the aquaculture industry may actually be polluting the oceans, disabling fishing communities, and abetting the collapse of the world’s fisheries.
Meanwhile, the $78 billion aquaculture industry1 insists that it is becoming more ecologically friendly and that there is every reason to continue enjoying tasty farmed salmon along with the growing array of species it is learning to farm.
Getting to the truth of the matter is of immense importance to the future of ocean fisheries. That’s because 50 percent of the seafood we eat—more than 60 million tons per year—comes from aquaculture,2 and we are becoming ever more dependent on farmed fish as we heedlessly continue overfishing. Without a major course correction, all major fish stocks could be commercially depleted to less than 90 percent of their historical levels by midcentury.
Of the collateral problems created by industrial-scale aquaculture, waste disposal is perhaps the most revolting. Like CAFOs on land, fish farms concentrate immense amounts of feces in relatively small areas. Fish excrement and excess feed result in the release of nitrogen, phosphorus, and chemical residues into the open ocean.3 A recent report by the Worldwatch Institute, a globally focused research organization based in Washington, DC, equates the fecal matter from a 200,000-fish operation to the sewage from a city of 20,000 to 60,000 people.4 The eutrophication caused by such massive waste streams can cause shellfish contamination, toxic algal blooms, and loss of biodiversity.
What’s more, cramped living conditions make fish vulnerable to disease. To compensate, fish farmers apply antibiotics, delicing compounds, and other medicines.5 A 2005 UN FAO report estimated that approximately 150 pounds of antibiotics are applied per acre of farmed salmon harvested in the United States.6 When pens are placed in the open ocean, these chemicals drift into the greater environment and can be ingested by other organisms.7 Health experts worry that the persistent use of low-level antibiotics is prompting the growth of antibiotic-resistant bacteria that may pose later health threats to humans.8
Several studies have also shown farmed fish to be laced with toxic polychlorinated biphenyls (PCBs),9 which bioaccumulate and move up the food chain as larger fish eat smaller ones. Laboratory tests commissioned by the Environmental Working Group in 2003 found that the average farmed salmon has 16 times the PCBs found in wild salmon, 4 times the levels found in beef, and 3.4 times the levels found in other seafood.10 These PCB studies may make fish consumers think twice about buying farmed salmon.
Farmed fish—with their increased prevalence of disease—also pose a risk to wild populations. In 1995, the southern oceans were hit by a massive herpes virus epidemic that originated near tuna ranches south of Australia. The virus spread at a rate of 30 kilometers a day, affecting at least 10 percent of the sardine population11 and sparking a mass starvation of gannets, penguins, and other seabirds. Although the epidemic has not been traced definitively to tuna farms, some marine scientists point to the industry as the cause.12 In the United States, a neurological disorder called whirling disease is reported to have spread from farmed to wild trout in more than twenty northeastern and western states13 since it was first detected in the 1950s.14 In 2008, multiple outbreaks of infectious salmon anemia (ISA) hit Chilean salmon farms. According to Juan Carlos Cárdenas, director of the Chilean nongovernmental organization Ecoceanos, the virus can spread at a rate of 1 percent of a caged population per day and was able to extend 1,200 miles in southern Chile in a single year.15
When ISA first appeared in 2008, many offshore aquaculture companies moved their production farms farther south in Chile, into waters still unaffected by the disease. Instead of lessening the problem, however, the industry actually extended ISA’s reach into the southern waters. Industry source Intrafish projected that Chile’s 2009 salmon output could decline by as much as 87 percent—a drop from 279,000 metric tons in 2008 to between 37,000 and 67,000 metric tons.16 Despite efforts to address the crisis, Chilean salmon stocks have been devastated, and the world’s food supply will be affected. Before the outbreak, Chile was second only to Norway in farmed salmon production and was the largest exporter to the United States. As a result of the Chilean crisis, an 18 percent shortfall in the global harvest of farmed Atlantic salmon is predicted for 2009, and perhaps 2010 as well.17
Disease is not the only thing escaping fish farms. The fish themselves often break loose. Roughly 2 million salmon escape into the North Atlantic each year,18 practically making wild salmon a minority in the open ocean. In Norway alone, between 250,000 and 650,000 salmon escape each year, and a full third of the salmon spawning in coastal rivers are of escaped origin.19 The escapes have been a major concern for wild salmon, whose genetics are downgraded when they interbreed with genetically inferior farmed salmon. For a population already facing numerous barriers—such as overfishing and destruction of spawning habitat—the last thing wild salmon need is an infusion of genes that will make them more docile and less able to survive on their journeys from birth to reproduction. By allowing fish to escape, open-cage aquaculture is working against the long-term health of ocean ecosystems, which depend on a diversity of robust wild genetic populations.
It’s not just wild fish that are thrown out of balance by aquaculture operations. Many factory fish farms can also pose risks to land-based ecosystems. Some aquaculture systems lean heavily on freshwater resources. Intensive carp and tilapia production uses over 20 gallons of freshwater per pound of meat.20 Shrimp farms use even more freshwater.21 Like the feedlots in Kansas or the hog buildings in North Carolina, these thirsty fish farms are draining local aquifers and consequently jeopardizing the ecosystems and human settlements that rely on freshwater. The U.S. Geological Survey estimates that aquaculture draws 3,700 million gallons of freshwater each day from American soils and surface waters.22 Consequences of this water-chugging industry can be seen in the United States and around the world.
In the Ranot region of Thailand, an influx of shrimp ponds in the late 1980s reportedly caused the average groundwater level to fall by more than 12 feet over three years.23 When aquaculture businesses and locals compete for natural resources, the locals—both humans and ecosystems—often lose. In addition to indirect competition for water, ecosystems and animals in fish farming regions have also been hit by more direct harm.
Throughout Asia and South America, the farmed shrimp industry has been responsible for the clearing of coastal ecosystems—mangrove forests in particular—to make space for aquaculture.24 This deforestation leaves locals who depend on the mangrove forests for harvesting wild crabs and shellfish without food, and can also trigger erosion and coral reef damage.
Death, wounding, and harassment of local fauna has also been a problem at some aquaculture facilities—caused either by intentional attack or by inadvertent problems such as net entanglement or depletion of wild fish resources that nourish many marine animals.25 Even if marine mammals, birds, and fish aren’t directly engaged by aquaculture personnel, it is becoming increasingly likely that their fates will be influenced by this growing industry. As the industry expands, so too does its appetite for fish meal to feed the caged fish. And with the market for fish meal booming, we see the general depletion of the smaller fish species that are vital for the ocean’s ecosystems. These are the previously abundant fish that support commercially valuable wild fish, marine mammals, and seabirds.
In her book Diet for a Small Planet, Frances Moore Lappé argued almost 40 years ago that grain-fed cattle were essentially “reverse protein factories” because they required many more pounds of plant protein to produce a pound of flesh. A similar dynamic exists in the global aquaculture industry, especially as it strains to satisfy our voracious appetite for top-of-the-food-chain carnivorous fish such as salmon, tuna, and shrimp.
“Aquaculture’s current heavy reliance on wild fish for feed carries substantial ecological risks,” says Roz Naylor, a leading scholar on the subject at Stanford University’s Center for Environmental Science and Policy. “And unless alternatives become commercially viable at a large scale, some key pelagic fisheries could be pushed over the edge of sustainability, thus reducing food sources for many other species in the marine food chain.”26
The aquaculture industry took off as wild fishing captures stagnated. Since 1970, it has grown by almost 9 percent per year to satisfy a global demand that has nearly doubled in that time, thus making it the fastest-growing food group.27
But there is a catch to this stunning human achievement. It takes a lot of other inputs, mainly other, “lesser” fish—also known as “reduction” or “forage” fish—to create the kind of fish we prefer to eat directly. These smaller pelagic fish are processed into fish meal and oil and then mixed with other ingredients to create pellets that are fed to penned-in fish. While the average ratio of wild fish input to farmed fish output has finally dropped to below 1 for the overall industry, many farmed fish still require far more than their weight in wild fish. For instance, it takes roughly 5 pounds of the smaller pelagic fish (open-seas species like anchovies, mackerel, and herring) to create 1 pound of Atlantic salmon.28
Industry and publicly funded research has significantly enhanced this efficiency—while reducing the percentage of fish and oil content in aquafeeds. “I would say cost, the sustainability of resources . . . and human health concerns have been driving researchers to find replacements for fish meal and fish oil . . . and we are doing this to the greatest extent possible,” says David Higgs, a Canadian government fish nutritionist who works closely with British Columbia’s $450 million salmon industry.29 (Reducing the fish content reduces the bioaccumulation of PCBs, which helps the industry’s public image.) But these improvements have been offset by the industry’s explosive growth. The salmon industry, the largest aquaculture sector, has made modest reductions in the amount of wild fish required to produce one unit of salmon in recent years, but total industry production has grown by a substantially greater percent.
There are more worrisome trends, such as the rapid expansion of other species now being farmed that have even higher fish feed requirements. Ranched tuna, for instance, dine on live pelagic fish, but it takes about 20 pounds of such inputs to get 1 pound of tuna ready for a sushi bar near you.30 (Tuna are ranched—corralled from the wild and then fed in anchored pens—because despite prodigious efforts, especially by Japan, no one has been able to raise them from eggs.)
“The problem is we’ve gone straight to the top; we are essentially, as some argue, farming tigers when we raise tuna or striped bass or cod,” argues Brian Halweil, a senior researcher at the Worldwatch Institute. “We need to start from the ground up and encourage farming of shellfish, which are the basic building blocks of a healthy coastal ecosystem, and from there move upwards to fish that eat algae, and then to fish that eat other fish. But putting all our attention on things like tuna and cod, while it may be incredibly profitable, is also very destructive from an ecological point of view.”31
Although environmentalists and industry dispute whether current harvesting is done at sustainable levels, there is no doubt that the global fish stock is a finite resource, and there is no end in sight for the growing demand. A staggering 37 percent of all marine fish catch is now ground into feed, up from 7.7 percent in 1948, according to 2006 research from the University of British Columbia Fisheries Centre.32 Much of that goes to China, where 70 percent of the world’s fish farming takes place.33
It may be a surprise that much of the global production of fish meal and fish oil goes to the livestock industry, mostly pigs and poultry. Aquaculture, however, has recently become the top consumer of fish meal and fish oil, its use rising dramatically from 10 percent in 1988 to over 60 percent in 2009.34 This share continues to rise, especially because, as fish meal prices have risen, the livestock industry has been quicker to substitute vegetable proteins than has the aquaculture industry. If current trends continue unabated, demand for fish oil will outstrip supply within a decade, and the same could happen for fish meal by 2050, says Naylor. These trends are reflected in rising fish meal prices as the wild fish used to produce fish meal become ever more scarce.
Wild fish stocks are further depleted by the aquaculture industry’s practice of tapping wild fisheries as seed for farmed populations. In parts of Asia, fish farmers bring young wild fish inland to stock lakes. Similarly, industrial shrimp operations use wild larvae to build their cultivated supplies.35 The use of wild seed stock—in concert with fish meal as feed—raises serious doubts about the viability of aquaculture as a solution to overharvesting of wild fish.
If international development agencies originally envisioned fish farming as an antidote to world hunger, they were mistaken to think that this antidote would come without costs. Ironically, the industry has done great damage to some small-scale fishermen and aboriginal peoples, encroaching on their traditional areas and competing for wild fish stocks. In the village of Ao Goong in southern Thailand, when shrimp ponds moved in alongside the local community, the villagers’ lives changed dramatically. Waste materials from the shrimp ponds—dumped both on land and in the ocean—killed the wild shrimp the villagers had subsisted on, poisoned their coconut trees, and tainted their well water.36 The traditional local economy and way of life were ruined by the arrival of irresponsibly managed commercial aquaculture.
In Bangladesh, the district of Khulna has also seen the destruction caused by shrimp farmers. Despite the institution of a shrimp-free zone, shrimp traders colluded with government officials to reject the zoning and destroy existing agricultural fields to make way for shrimp ponds. The conflict has taken a physical toll on the residents as well. Women have been sexually abused by shrimp farm employees, and over a hundred villagers have died in the struggle against aquaculture’s takeover of land.37 Similar stories can be told in other fishing communities around the world.
More broadly, fish farms are creating a scarcity of affordable seafood for the world’s poor. The reliance on wild fish to fuel the aquaculture industry presents food security dilemmas for developing countries. World Wildlife Fund—Germany has been investigating whether the recent surge in illegal emigration from West Africa to Europe is related to the deterioration of local fishing conditions. And in Peru, which hosts the world’s largest anchovy industry, many locals are living in poverty and showing signs of fish protein deficiencies. Peru exports over 2 million tons of fish each year,38 mostly anchovies for fish meal to fuel aquaculture in China and elsewhere.39 As an increasing share of these small fishes is fed into aquaculture, the foundation for healthy wild fisheries erodes away and there is less available for those who might benefit from wild fish as a key direct source of protein.
Instead of offering an alternative to wild fish—and allowing wild fisheries to rebound from decades of overfishing—aquaculture is often undermining the very foundation of marine ecosystems. Some marine scientists are now concerned that the Antarctic krill population is at risk. Krill, a fundamental building block for many large marine species, including whales and penguins, has already been in decline owing to global warming. But now krill harvesting companies are scooping up massive amounts of the invertebrate animals to be used as fish farm feed and health supplements. According to the Antarctic Krill Conservation Project, the factory trawler Saga Sea— operated by Norwegian multinational corporation Aker ASA—is able to continuously vacuum millions of krill.40 Other firms are eyeing similar technology. Although the harvesting companies estimate that 400–500 million tons of krill remain, the British Antarctic Survey puts the number at only 110 million tons.41 The legal catch limit is 4 million tons,42 and new suction harvesting techniques will allow the industry to more easily meet this target. “Whales, penguins, seals, albatrosses and petrels—all those creatures we think are absolute icons of Antarctica—depend on krill,” said Richard Page, a marine reserves expert with Greenpeace International. “It’s part of the global commons, and one of the most pristine environments on Earth.”43
In contrast to today’s farmed salmon and tuna, the fish species at the core of the millennia-long tradition of fish farming in Asia and parts of Africa—catfish, carp, and milkfish—actually require less weight in fish inputs than the weight ultimately harvested because they are herbivorous or even omnivorous. To traditional fish farmers, the idea of feeding several times more pounds of fish meal to get one pound back would seem sheer folly. “Ultimately that is really where the solution is—to cut back on these carnivorous species and turn our attention to these plant-eating ones,” says U. Rashid Sumaila, a renowned expert at the University of British Columbia. “Whether we are willing to do that is another thing, but that’s the fundamental solution.”44
The earliest known fish farming dates back to China, where raised carp have fed people for millennia. Small inland carp ponds often existed alongside farms; waste from adjoining pig or duck pens would feed the carp, and several times a year the rich bottom soil from the ponds would be reapplied to neighboring fields as fertilizer. This system continued until the Tang Dynasty, when a linguistic fluke precipitated the evolution of traditional aquaculture. Legend has it that a close similarity between the emperor’s name and the word for carp prompted many farmers to trade carp for other fish species, not wanting to risk associating the emperor with a farmed fish. Thus the Chinese polyculture system—raising many types of fish together—was born.45
Even today, China’s traditional pond systems continue to be some of the most productive freshwater fisheries in the world. Part of their secret is the near elimination of the concept of waste: one species’ waste becomes another species’ food. Many of today’s industrial aquaculture systems allow unused nutrients to attract bacteria, insects, and birds—depleting nutrients available for the fish. In these operations, untapped wastes create ecological nightmares.
In contrast, in the traditional Chinese closed-loop pond system, each fish species fits into a particular niche, resulting in a balanced community. Silver carp and tilapia feed on phytoplankton; bighead carp graze on zooplankton; grass carp, Wuchang fish, and common carp eat green fodder; common carp, black carp, and mud carp forage in sediments at the bottom of the pond. From China to India to Thailand, this balanced approach to fish farming continues to feed many rural dwellers without the unintended consequences of modern aquaculture.46
The traditional pond model has inspired some twenty-first-century fish farmers to aim for more technologically complex versions of its nutrient cycling. Entrepreneurs and academics have been looking at various ways to cycle nutrients: sending fish waste to nearby agriculture fields; using fish as wastewater treatment; or growing vegetables hydroponically on top of fish ponds. Forward-looking aquaculture models are also pursuing new strategies to treat, recycle, and recirculate freshwater for inland aquaculture. But when governments fail to put a price on water use or to adequately regulate it, profit-oriented aquaculture companies have little incentive to save water, stop the escape of waste and fish into the wild, or provide adequate buffers between their fish and other water sources.
Recognizing the need for industry to move toward these more sustainable practices, the World Wildlife Fund (WWF) has spurred efforts to craft voluntary industry standards aimed at minimizing or eliminating the main environmental risks. WWF has been facilitating a multistakeholder dialogue process including producers, buyers, and various nongovernmental organizations since 2004. “This is a major priority for us,” says Jose Villalon, who heads WWF’s recently expanded aquaculture team. Standards will yield certifications; the first two—covering tilapia and pangasius (catfish)—have progressed through a public comment period. The draft standards provide specific targets for site location, water quality, antibiotic use, feed efficiency, and fair labor practices for the farmed tilapia industry. Standards for other species are proving more contentious, with shrimp and salmon not expected until 2010 at the earliest.
In the meantime, the meaning of sustainability is a movable metric shaped largely by restaurants, where 70 percent of seafood consumed in the United States is eaten.47 “As chefs, we need to celebrate diversity in the oceans so that we are not relying too heavily on any one species,” avows Peter Hoffman, owner of Manhattan’s Savoy Restaurant and a board member of the 1,000-strong Chefs Collaborative, an organization committed to “educating chefs about the sustainability of the seafood they purchase and serve.” That’s partly a creative challenge, making tilapia, for instance, taste as interesting as seared ahi. As we move to herbivorous fish like catfish, tilapia, and carp, and to bivalves like oysters, mussels, and scallops, we eliminate the reverse protein problem.
Going down the food chain means no real diminution in health benefits but can reap significant ecological pluses. This calculus may already be helping to regenerate the dimmed luster of the modest shellfish, including the oyster, which is the subject of reseeding campaigns from Long Island Sound to Washington State’s Puget Sound, where it has been most successful. Not only are oysters, along with other mollusks, good for you—oysters are freakishly high in zinc, needed to create testosterone—they feed themselves.
And by being able to thrive even in slightly polluted water, oysters also provide an invaluable ecological service; a single adult oyster can filter 50 gallons of water a day. When Jamestown founder John Smith first sailed into the pristine Chesapeake Bay four hundred years ago, he had to navigate around oyster reefs 20 feet high and miles long that were effectively filtering the entire estuary—the country’s largest—every few days, according to Rowan Jacobsen, the author of A Geography of Oysters: The Connoisseur’s Guide to Oyster Eating in North America. “If we can get oysters to historic levels, they can make a huge difference,” Jacobsen says. But his dream of a return to the oyster’s golden age in the late nineteenth century—when 100 million pounds of oysters were harvested from the Chesapeake every year, in contrast to today’s 250,000-pound haul—is a long way off. To most diners, salmon and shrimp are still the seafood treats of choice.