Fish farming is one of the most intensive forms of animal agriculture. As many as 40,000 fish may be crammed into a cage, with each fish given the equivalent of half a bathtub of water in which to spend its life. The wild salmon migrates thousands of miles, but the caged fish goes nowhere. Instead of streaking through the ocean or leaping up rocky streams, farmed salmon spend 3 years circling lazily in pens, fattening up on pellets of salmon chow. For that rich pink hue fish are given a steady diet of synthetic pigment. Without it, the flesh of these salmon would be an unappetizing, pale gray.
Begun in Norway in the late 60ís, salmon farming has spread rapidly to cold-water inlets around the globe. Worried about the environmental toll, British Columbia imposed a ban in 1995 on any new farms. The industry responded by stuffing on average, twice as many fish into each farm. Today farms typically put 50,000 to 90,000 fish in a pen 100 feet by 100 feet. A single farm can grow 400,000 fish. Some raise a million or more. The moratorium on new farms was lifted in September 2002 under pressure from the industry. As a result, 10 to15 farms are expected to open each year over the next decade.
Many farms are using sturdier nets to stop fish from escaping and to keep intruding sea lions out. The sea lions are shot if they penetrate the perimeter. Intensive man-made shrimp farms have been equally staggering. In Ecuador for example, 500,000 acres have been given over to shrimp farms with 80 percent of the shrimp exported, more than half going to the United States. The costs of this growth include coastal pollution, displacement of local people from their land, and the clearing of large tracts of coastal mangrove forests.
The ecological destruction caused by fish farming, particularly of shrimp is so great that a report published in 2000 by New Internationalist compared the environmental destruction caused by fish farming to that caused by replacing tropical forests with cattle ranches. Independent studies conducted in Canada, Scotland and the United States found that farmed fish contained much higher levels of pollutants, including ten times more PCBs and cancer causing toxins than wild fish. Fish wastes and uneaten feed smother the sea floor beneath these farms, generating bacteria that consume oxygen vital to shellfish and other bottom-dwelling sea creatures.
Disease and parasites run rampant in densely packed fish farms. Deadly sea lice infestation are common. Pesticides are fed to the fish and toxic copper sulphate is used to kill algae that build up on the nets. Antibiotics have created resistant strains of disease that infect both wild and domesticated fish.
Of all the concerns, the biggest turns out to be a problem fish farms were supposed to alleviate the depletion of marine life from over fishing. The fish farms contribute to the problem because the captive salmon must be fed. It takes about 2.4 pounds of wild fish to produce one pound of farmed salmon, according to Rosamond L. Naylor, an agricultural economist at Stanfordís Center for Environmental Science and Policy. That means grinding up a lot of sardines, anchovies, mackerel, herring and other fish to produce the oil and meal compressed into pellets of salmon chow.
Fish Farming is not taking the strain off wild fisheries. On the contrary, it is a practice that unsustainable. About 1 million salmon which are favored by farmers because they grow fast and can be packed in tight quarters have escaped through holes in nets in the Pacific Northwest. Biologists fear these invaders will out-compete Pacific salmon and trout for food and territory, hastening the demise of the native fish. An Atlantic salmon takeover could knock natureís balance out of whack and turn a healthy diverse habitat into one dominated by a single invasive species. Preserving diversity is essential because multiple species of salmon have a better chance of surviving than just one.
The prospect of genetically modified salmon that can grow six times faster than normal fish has heightened anxiety. Critics fear that these "frankenfish" will escape and pose an even greater danger to native species than the Atlantic salmon. Also worrisome to vegetarians and non-vegetarians alike is the experimentation involving splicing fish genes with tomatoes and other plant-based foods.
Meanwhile, 22 million tons of wild fish were used by the livestock industry for pig and cow feed in 1997. That is a figure greater than the combined weight of the entire human population of the United States.
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