PUERTO MONTT, Chile -- Newcomers to Patagonia can't even make it out of the airport here without encountering a stunning view of sparkling Lake Llanquihue, with the snow-peaked cone of Osorno volcano rising in the background.

It's a huge photograph hanging in the terminal, actually, and the buoys pictured floating in the glassy water give away its intent: It's an ad for commercial salmon farming, which has become the economic backbone of Patagonia's lakes region.

The salmon industry barely existed here 20 years ago, but the same crystal waters and unspoiled vistas that help power the region's booming tourist industry caught the attention of seafood producers. Now, when diners in the United States cut into a salmon fillet, odds are that the fish matured in one of the net pens constructed in this region's waters.

Spurred partly by a U.S. appetite for salmon that has quadrupled in the past decade, the massive growth of the local salmon industry now has some fearing that its best marketing tool -- that fabled Patagonian purity -- isn't quite what it used to be.

"The irony is that the same thing that caused the salmon producers to come here in the first place -- the pristine quality of the lakes -- is now being lost because of the production of salmon," said Jorge León-Muñoz, who co-wrote a World Wildlife Fund report detailing some of the industry's effects on the environment.

Using a clear plastic tube to bore into lakebeds, scientists can plainly view the problem. Round pellets -- the fish-based food that is fed to the salmon -- have fallen to the lakebeds unconsumed and ended up buried in the dirt. Those pellets, combined with the salmon's feces, add nutrients to the water that spur plankton growth and deplete oxygen, which can make the water unlivable for many native fish.

"You see species of algae and types of bacteria that weren't there before," said Guiliana Furci, a salmon specialist with Terram, a Santiago-based environmental research institute. "There's a huge organic input in the lakes."

According to official statistics, evidence of oxygen deficiency was found at 20 percent of salmon farms operating on Chile's lakes between 2003 and 2005.

Full Story: http://www.washingtonpost.com/wp-dyn/content/article/2007/12/01/AR2007120100763.html