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Aquaculture: Can fish farmers learn from nature?

With the number of fish farms expanding throughout the U.S. and elsewhere, the health and environmental hazards associated with these farms are being examined more closely.According to a June 8, 2005, article in the “Christian Science Monitor,” the rapidly growing human population and an awareness of the health benefits of eating fish have spiked the fish market to 110 million metric tons annually. Traditional fishing methods cannot meet those demands because rivers and oceans throughout the world have been over-fished. The National Oceanic and Atmospheric Association’s manager, Michael Rubino, told the “Christian Science Monitor, “Any increase in supplies is coming from aquaculture.” By 2030, over half the fish consumed by humans will be raised on fish farms.How fish are farmed varies by species.Fish hatcheries produce fingerlings or eggs for the farms. According to AquaSol, an aquaculture-consulting firm, catfish and tilapia are then grown in ponds.Shrimp eggs are spread throughout flooded fields, ranging in size from 240 to 1,200 acres, allowing prawn production to occur in places far from the ocean, such as New Mexico.Salmon, cod and other large ocean species are farmed in metal cages or pens created from strong nets and located in saltwater inlets or close to the shore. Clams, mussels and oysters grow on wooden racks or on poles suspended in tidal inlets.Jim Rubingh from the Colorado Department of Agriculture said, “Most of the state’s aquaculture consists of raising trout for recreational purposes.” And over half the trout purchased in Colorado come from farms in Idaho. However, Rubingh said some farmers are raising tilapia in the San Luis Valley. Grocery stores are beginning to carry it, he said.Environmentalists, fishermen and aqua farmers themselves are questioning some aquaculture practices.Jane Goodall, an anthropologist known for her work with primates, examined the health and environmental problems associated with farm-raised fish in her book, “Harvest for Hope.” She said there is an environmental concern about aquaculture feed. Great quantities of small ocean-schooling fish are caught and ground into fish pellets. Goodall said this practice depletes small fish species while also removing the food source for larger fish.The nutritional value of wild salmon makes reproducing it in captivity a top priority. But, salmon farming techniques can harm both wild salmon and the environment, while producing fish without the same nutritional value or taste as wild salmon.Goodall writes, “In a place where hundreds of wild salmon had traditionally spent a few hours … over 1 million densely packed fish were placed in a pen that would be there for 18 months before … harvest.” She said fish farms in British Columbia dumped “the equivalent amount of sewage that would be generated by a city of a million people.”The economic and environmental implications of this practice are huge to fish farmers, according to AquaSol. Think of a pen as a large fish bowl. Crowded into pens, the fish become more susceptible to viruses. Antibiotics added to their feed combats illness, but over time, viruses adapt. More antibiotics are added, driving up the cost of the fish pellets. In Goodall’s book, she notes that more antibiotics are used today in aquaculture, per pound of livestock, than in any other form of farming.Large farmed-fish species, especially salmon, also are infected with sea lice that proliferate to levels unseen under natural conditions. Clouds of lice surrounding the pens have infected passing juvenile wild salmon and sea trout, eating their skin, eventually destroying most of these wild fish in Scotland, Norway and Ireland. Today, farmed salmon are treated with pesticides to kill the lice; unfortunately, the pesticides remain in the fish for human consumption.Kimberly Ordon, an attorney in Washington State who works to protect the water and territorial fishing rights of the Tulalip Tribes, explained the environmental problems she encountered with large-scale salmon farms. “The fish are crowded into large pens. Fish waste, fish food and dead decaying fish cause the nitrogen under the farms to greatly increase, depleting the water of oxygen and killing off most plants and wild fish in the area,” Ordon said.”The farmed fish has an oily taste, and its flesh is much softer than the wild variety,” she said.Alexandra Morton, a marine biologist, examined the flesh of over 800 domestic salmon and found a consistency likened to mashed potatoes. Her research, cited on the Pacific Fisheries Resource Conservation Council Web site, found the salmon were infected with Serratia, bacteria resistant to 11 of 18 antibiotics.Goodall also states in her book that farm salmon contains higher rates of unhealthy fats and lower amounts of omega-3 fatty acids than its wild cousin.In the early 1990s, the World Bank convinced governments to promote shrimp farms as a way to generate revenue for Third World countries. Today, annual shrimp sales have reached $60 billion. Much of the shrimp is imported to the U.S. and Japan from Indonesia and Thailand.Pesticides, antibiotics and fecal contamination are also associated with shrimp farming. But, according to Goodall’s “Harvest for Hope,” a bigger environmental disaster occurred when more than 40 percent of the world’s mangrove trees were cut down to make room for shrimp farms. Mangroves act as a protective barrier against waves.At the same time fish farms create environmental problems, aquaculture supplies a source of protein for the world, Goodall said in her book. However, fish farms should adopt proper aquaculture practices. In Scotland, Johnson’s Seafood farms cod organically without any antibiotics or pesticides by dramatically decreasing the number of fish kept in a pen.According to the University of Georgia Web Site, Butterfields, a catfish farm consisting of 93 ponds in Alabama, uses the same methods the Chinese first developed to raise fish. Butterfields created an environment as close to nature as possible by stocking ponds with a number of different species. Tilapia and carp eat algae, keeping the oxygen levels high. Bluegill, crappie and bass balance out the eco-system and are eaten by the catfish, eliminating the need for fish pellets. Because of pollution in many rivers and streams, catfish farmed without pesticides or antibiotics are far safer to consume than catfish from the Mississippi or other rivers, according to the Environmental Protection Agency.Thierry Chopin, a marine biologist from the University of New Brunswick, reported in the journal “Aquaculture” that raising multi-species may also be a better method for ocean aquaculture. His team raised salmon, mussels and seaweed off the coast of Canada, reducing nitrate levels around salmon pens by 60 percent because of the interaction between the species.According to the “Christian Monitor,” the Bush administration is backing a bill allowing fish farms up to 200 miles offshore in order to compete against foreign aquaculture. The plan, if approved, would open 3.4 million square miles of ocean to American aquaculture.The experts, however, say the success of aquaculture is not based on competing with a foreign market; it’s all about embracing health.

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