Meatonomics (25 page)

Canada had formerly banned the hunting of another threatened species, the harp seal. While up to 9 percent of a typical harp seal's diet can consist of cod, the seal also helps the cod population by eating larger fish that prey on cod, like halibut, and accordingly is thought to have little overall effect on cod populations.
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Nevertheless, several members of the Canadian government publicly blamed the harp seal for the cod fishery's collapse. In 1995, under the direction of Newfoundlander Brian Tobin, Canada's minister of fisheries and oceans, the country lifted the seal hunting ban. Canada now hosts the largest marine mammal hunt in the world, with an annual quota of 330,000 harp seals.

Three billion people around the globe regularly eat what the French call, in something of a naïve misnomer, “fruits of the sea.” As output from the planet's wild fisheries drops like a barometer before a storm, aquaculture—or fish farming—is increasingly taking up the slack. That makes it the planet's fastest growing food production system, and today, half the fish Americans eat is raised in tanks, cages, and other confinement systems.
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Many believe aquaculture is a sustainable, cost-effective way to feed the planet, especially as the production
of meat and dairy is increasingly seen as unsustainable at the levels the world demands. Is fish farming the way of the future?

Recall the Polyface Farm model for land animals. The technique of ecological rotation for farming livestock is one of the most sustainable ways (even if not
completely
sustainable) to feed animals, manage waste, and avoid degrading the land. In a similar vein, innovative fish farming methods surround the target species with a mini-ecosystem to promote natural waste management. Salmon, for example, might be raised next to shellfish, which filter solid waste, and seaweed, which processes nitrogen. One such efficient system is called Integrated Multi-Trophic Aquaculture (IMTA), and it's in use today at several aquatic farms in Canada's Bay of Fundy. IMTA isn't perfect, but it does help address one of the biggest concerns in fish farming—the effects of fish waste on surrounding ecosystems.

But waste is only one of several issues in aquaculture sustainability. In fact, the most eco-friendly way to raise fish is to grow them in land-based tanks or ponds where waste is completely contained, disease is minimal, and escapes are impossible. However, unlike open-water systems, land-based systems require costly processes to remove waste and to maintain water's salinity, temperature, and oxygen content.

Fish-farming scientists at the University of Maryland have sought to address the ecological limitations of fish farming. Led by Yonathan Zohar, chair of the university's Department of Marine Biotechnology, the group has developed a fully self-contained, land-based aquaculture system. The Maryland system uses bacteria to filter nitrogen from the water and microbes to convert waste to methane for use as a biofuel. It's about as eco-friendly as fish farming can be. However, it's not ready for production—and may never be. Not surprisingly, this system is limited by its high operating costs and the huge amounts of energy needed to run it.

Aquaculture methods like IMTA and the Maryland system are promising. But just as Polyface Farm is well-intentioned but ultimately unsustainable, these and other innovative fish farming methods also fall short. For starters, land-based systems, even those that don't take the costly extra step of recycling water and waste, are
expensive. In a cage or pen system, by contrast, because the permeable container sits in open water, operators spend nothing to dispose of waste or to provide a constant supply of clean, oxygenated water. This fundamental difference allows cage and pen systems to operate much more cheaply than land-based systems. It also explains why cage aquaculture is the predominant method of fish farming throughout the world.
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IMTA, for its part, may be an effective way to protect ecosystems from fish waste. However, IMTA doesn't address a number of other ecological concerns associated with open-water fish farming discussed below. And even if they did, IMTA and similar systems are in use at only a handful of fish farms. The reality is that fish farm operators, like any business owners, look to the bottom line—and we know that price tags are closely watched in the world of meatonomics. That's why inexpensive cage-based systems are the standard. And as experience shows with largely futile efforts to reform land-based animal production methods, in an industry characterized by regulatory capture and heavy influence over lawmaking, it's likely to stay that way. Hence, in evaluating fish farming, while the experiments of innovators on the fringe are interesting, the relevant point of inquiry is the system as it exists today and is likely to persist in the future. And here's where the water gets a bit murky. Considering the many documented environmental impacts of aquaculture as practiced today in North America and around the world, the claim that it's sustainable emerges as something of a fish story.

Fish farms are the factory farms of the sea. And just like CAFOs, aquaculture relies on hyper-confinement to raise the largest number of animals in the smallest possible area. With two-thirds of the planet covered in water, it might not be necessary to stock fish as densely as battery hens. But necessary or not, that's how it's done. Foot-long trout, for example, are raised in densities as tight as twenty-seven to a bathtub-sized space.
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And just as such tight densities cause problems in factory farms, they cause a variety of issues in fish farms.

Fish are susceptible to parasites. While these vermin can only achieve infestation at high density levels, a typical fish farm provides the Goldilocks-like stocking levels they need.
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Atlantic salmon, the most common cage-reared fish, are particularly prone to sea lice. A parasitic crustacean measuring an inch or longer and resembling a miniature horseshoe crab, these dogged little creatures eat the blood, mucus, and tissue of living salmon. Because sea lice can only survive in saltwater, they typically drop off in the wild as their hosts migrate into fresh water. In saltwater fish farms, however, lice remain attached until removed by chemicals or, in some cases, gobbled by lice-eating cleaner fish.

A female sea louse lays up to twenty-two thousand eggs during her seven-month lifespan.
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On tightly packed fish farms, newly hatched juvenile lice have little trouble finding a host to chew on. Picture, if you will, the huge numbers of concentrated salmon and egg-laying sea lice in a typical fish farm environment. With more than five hundred thousand salmon in an average farm, if just one in ten fish hosts just one female louse, and each louse lays just half her capacity, that's a localized plague of more than 500 million baby sea lice. Besides hurting farmed fish, these infestations also harm the surrounding ecosystem and its inhabitants. Like a swarm of tiny locusts, the hungry parasites explode into their surroundings and snack on any wild salmon in the vicinity.

Not surprisingly, sea lice from salmon farms are killing wild salmon populations.
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On Canada's Pacific coast, for example, sea lice infestations are responsible for mass kill-offs of pink salmon that have destroyed 80 percent of the fish in some local populations.
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But the damage doesn't end there, because eagles, bears, orcas, and other predators depend on salmon for their existence. Drops in wild salmon numbers cause these species to decline as well.
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Some farmers respond to lice by dosing the water with concentrated chemicals that kill the tiny creatures. Not surprisingly, adding toxins to the ocean harms the local ecosystem.
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One study, for example, found that cypermethrin (used to kill lice on salmon) kills a variety of nontarget marine invertebrates, travels up to half a mile, and persists in the water for hours.
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But even more threatening to local ecosystems than sea lice and the chemicals that kill them are the massive quantities of waste generated by most fish farms. Consider aquaculture's effect in Scotland. In 2000, Scotland's fish farm industry created as much waste-based nitrogen as did two-thirds of the country's human population of 5 million—plus almost double the phosphorus that the human population generated.
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Fish waste typically falls as sediment to the seabed in sufficient quantities to overwhelm and kill underlying marine life in the immediate vicinity and for some distance beyond. It also promotes algal growth, or the ironically named process of eutrophication (literally, “providing nourishment”), which reduces water's oxygen content and makes it less capable of supporting life. In 2008, the Israeli Ministry of Environmental Protection shut down two fish farms in the Red Sea that produced 2,000 tons of fish annually, because research showed that eutrophication from the fish farms was damaging the region's coral reefs.

Aquaculture also results in regular escapes by farmed fish into the world's oceans. In the North Atlantic region alone, up to 2 million runaway salmon escape into the wild each year.
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The result is that at least 20 percent of supposedly wild salmon caught in the North Atlantic are of farmed origin.
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Escaped fish breed with wild fish and compromise the gene pool, harming the wild population. Embryonic hybrid salmon, for example, are far less viable than their wild counterparts, and adult hybrid salmon routinely die earlier than their purebred relatives.
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Like hitting a fighter when he's already down, this gene-pool degradation causes further declines in wild fish stocks that have already been pounded by overfishing.

Another direct and unfortunate consequence of aquaculture is overfishing—the practice of capturing more fish than a fishery can regularly replace. Throughout the world, as fish farming explodes to meet surging demand, industrial fishing operations catch prey fish like anchovies, herring, and mackerel in increasing numbers to feed to captive fish. The top ten farmed fish consume an average of 2 pounds
of wild fish for each pound they weigh at slaughter. The ratio is even higher for strictly carnivorous fish like salmon and tuna, which eat up to 5 pounds of wild fish per pound raised.
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The aquaculture industry's voracious appetite means that prey may soon join predators in the lists of overexploited and threatened fish stocks. Seven of the world's top ten fisheries are prey fish, with today's total catch in this category exceeding that of 1950 by a factor of four.
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Most of the millions of tons of prey fish caught each year are consumed by aquaculture—the latest data show that farmed fish eat between 50 and 80 percent of all prey fish captured.
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(Nearly all of the rest, by the way, is fed to pigs and chickens in factory farms.)

But wild animals have to eat too, and thousands of species depend on these little marine creatures. As stocks of prey fish decline, predator populations deteriorate in lockstep. In 2009, the nonprofit group Oceana released a report titled “Hungry Oceans,” which highlighted the problem of dwindling predator populations. The report blames the depletion of prey fish stocks for declines in whales, dolphins, seals, sea lions, tuna, bass, salmon, albatross, penguins, and other species.
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“We have caught all the big fish and now we are going after their food,” said Margot Stiles, lead author of the Oceana report. The result, said Stiles, is “widespread malnutrition” in the oceans.
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The main force behind this crisis, according to the report, is aquaculture's need for feed.

One way to reduce the quantity of fish used as feed in aquaculture is to raise herbivorous fish like tilapia. Unlike salmon, tilapia can thrive on pellets of corn or other grains. However, tilapia raised on this unnatural diet provide low levels of the omega-3 fatty acids that many people consider one of the main benefits of eating fish. That's because omega-3s originate in aquatic plants and are found in fish that eat those plants, but are not present in land-cultivated feeds. As a result, 3 ounces of farmed salmon typically contain more than 2,000 milligrams of omega-3s, while the same portion of farmed tilapia contains only 135 milligrams.
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Moreover, research shows that farmed tilapia contains fatty acids at levels which increase the risk of heart disease. A 2008 paper published in the
Journal of the American Dietetic Association
found that omega-6 fatty acid levels in farmed
tilapia were “so high they can be considered detrimental.”
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Another problem with tilapia is the African fish's propensity to invade lakes and displace native species through aggressive feeding and breeding. In fact, escapes from a tilapia farming operation in Lake Nicaragua, the largest lake in Central America, are blamed for the disappearance of the lake's less aggressive species like rainbow bass.
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The upshot is even if tilapia might take some pressure off diminishing prey fish populations, the downside is considerable.

Yet perhaps the most surprising way that fish farms affect wild fisheries is through an economic phenomenon known as the Jevons paradox. William Jevons was a 19th-century economist who noted that as better technology made coal-burning equipment like steam engines more efficient, demand for coal counterintuitively rose instead of falling. That's because efficiency improvements lead to economic expansion and higher commodity sales, negating the effects of any efficiency per unit produced. Similarly, critics argue, as aquaculture makes fish production increasingly efficient, and fish becomes more widely available and less expensive, demand for fish increases across the board. This of course drives more fishing, which hurts wild populations.

Can higher production efficiency really spur greater demand for fish? Consider the change in worldwide salmon production and demand from 1987 to 1999. During this period, salmon hatcheries widely replaced natural salmon spawning areas lost to habitat destruction. As the result of lower prices and wider availability, world demand for salmon increased more than fourfold during this period.
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Although hatcheries were expected to ease the pressure on wild salmon populations, the increased demand they caused actually aggravated the pressure.
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Such supply-driven effects are common around the world, as increased availability and lower production costs—fueled by subsidies and industrial methods of fishing and fish farming—help lower prices and spur consumption.
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