Ecology And Environment

Do the Benefits of Salmon Farming Outweigh any Detrimental Effects



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It's hard to beat the taste of a moist, delicious salmon steak or fillet. Baked, grilled, or barbequed, salmon is absolutely scrumptious! In addition, salmon in its natural state is high in protein and full of omega-3 fatty acids, making it healthy for human hearts and brains. Unfortunately, though, just as people across America discovered the health benefits of eating this succulent fish, wild salmon stocks in the Pacific Northwest and Alaska crashed due to dam construction and over-fishing. In order to keep up with booming demand, salmon began to be raised in enclosed oceanic farms, the "feedlots of the sea." Today, almost 70% of the salmon in restaurants and supermarkets comes from these farms. Increasing evidence suggests, however, that farmed salmon may not be beneficial after all, for humans or for the environment.

EFFECTS ON HUMANS

A 2002 government study in the U.K. found that farmed salmon is the most contaminated type of food sold in grocery stores, containing more toxins than meat, vegetables, and all other kinds of seafood. In fact, every sample the researchers tested contained a cocktail of at least three highly toxic chemicals. Common contaminants in farmed salmon include mercury, PCBs, and PBDEs. Mercury poisoning can result in cognitive delay for children; PCBs, banned since the 1970s but still present in the environment, have been linked with skin and eye lesions, liver cancer, and suppressed immune response; and PBDES, which are still used as fire retardants in fabric and electronics, can cause neurological impairment and liver damage, as well as disrupting the body's hormonal systems. Salmon also bio-accumulate pesticide run-off from farms. Farmed salmon, which spend their entire lives in coastal waters, have 10 times as much of these nasty chemicals in their flesh as do wild salmon. Many governments now recommend that people limit themselves to one serving per month of farmed salmon, and that women of child-bearing age avoid it altogether.

What about that lovely pink color? Salmon in the wild achieve their look through a diet rich in shrimp and krill, but a farmed salmon's meat is a sickly gray color unless the farmer adds pink dye to the feed. The dyes used are canthaxanthin and astaxanthin. Unfortunately for fish-eaters, canthaxanthin can damage the retinas in human eyes.

In addition, farmed salmon lived crowded together in pens, which makes them susceptible to disease. Fish farmers add massive loads of antibiotics to salmon feed, a practice that leaves antibiotic residues in the meat, and can help resistant strains of bacteria evolve. It's not an appetizing thought; drug-resistant bacteria from your farmed salmon dinner could be growing in your refrigerator or on your counters and cutting boards. If you must eat farmed salmon, handle the fish very carefully and use bleach on your preparation surfaces afterward.

EFFECTS ON THE ENVIRONMENT

The environmental cost of farming salmon begins with their feed. Normally, humans don't raise predators for food: it's just not efficient to feed tons of meat to bears, dogs, or lions, and then eat the carnivores. But salmon are also predators, high on the ocean food chain. In order to produce just one gram of salmon meat, fish farmers have to feed the salmon 5 grams of smaller fish, such as North Pacific herring. Increasing demand for farmed salmon means that wild salmon, as well as predators like sea birds, seals, and whales, are finding their hunting grounds stripped of herring by factory trawlers. Those herring are then ground into fish meal and fed to farmed salmon, while the wild creatures starve.

Once the farmed fish eat all those herring, of course there will be waste coming out the other end. A salmon farm with 200,000 fish produces as much fecal matter as 62,000 people-but the fish don't have a sewage treatment plant. Their waste, full of antibiotics and other chemical additives, drifts down to the sea floor, where it smothers crabs, shellfish, and anything else unlucky enough to live below.

Escapees are another potentially catastrophic problem. Salmon are large, powerful fish, capable of jumping up waterfalls in order to reach their spawning grounds. It's hard to keep them contained. Each year, about 2 million Atlantic farmed salmon escape their holding pens in the Northwest and British Columbia, then mix and interbreed with wild Pacific salmon in the sea. Not only do they harm their wild cousins by competing for food and spreading diseases: they also do genetic damage. A 2003 study found that the hybrid young fish are practically non-viable; 70% of them died during their first few weeks of life.

In addition, Pacific salmon are highly sensitive to introduced Atlantic sea lice. In fact, just being parasitized by a single sea louse is enough to kill a small Pacific chum or pink salmon fry. Adult salmon also can be disabled or killed by lice infestations. The sea lice problem is exploding around Pacific Ocean bays and inlets that house Atlantic salmon farming facilities; a survey of one typical farm in British Columbia found that the 1/8 mile wide salmon pens were surrounded by a cloud of swarming sea lice more than 19 miles in diameter! Wild Pacific salmon have to pass through that cloud as they migrate out to sea and then back to their natal rivers again to spawn, and inevitably, they pick up some of the devastating parasites on the way.

Farmed salmon is in plentiful supply, and thus cheaper than wild fish at the cash register. However, once you tally up the potential harm to your family's health, plus the environmental devastation caused by salmon farming, farmed salmon begins to look like a very poor bargain indeed.



Sources:
"Farmed salmon harbour pollutants," Nature (Jan. 9, 2004).
http://www.nature.com/news/2004/040105/full/news040105-10.html

"Grocers sued over artificial color in farmed salmon," Larry Lange, Seattle Post-Intelligencer (Apr. 24, 2003). http://seattlepi.nwsource.com/local/118986_salmon24.html

"No Farm, No Foul," Umbra Fisk, Grist.org (Apr. 23, 2002).
http://www.grist.org/advice/ask/2002/04/23/umbra-farmedfish/index.html

"Mortality Rate for Juvenile Pink Oncorhychus gorbuscha and Chum O. keta Salmon Infested with Sea Lice Lepeophtherius salmonis in the Broughton Archipelago," Alexandra Morton and Rick Routledge , Alaska Fishery Research Bulletin Vol. 11 No. 2. (Winter 2005). http://www.adfg.state.ak.us/pubs/afrb/vol11_n2/mortv11n2.pdf

"Lice Age: Farmed Salmon infect Wild Stock with Sea Lice, Study Finds," Grist.org (Mar. 31, 2005). http://www.grist.org/news/daily/2005/03/30/3/index.html

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