Stephanie Kwisnek, a spokeswoman for the F.D.A., said that she did not know the percentage inspected. But she said the F.D.A. tested 40 samples of the 114,320 net tons of salmon imported from Chile in 2007. None of them tested positive for malachite green, oxolinic acid, flumequine, Ivermectin, fluoroquinolones or drug residues, she said.

The F.D.A. is planning an inspection trip to assess Chile’s overall controls on its farmed salmon, she added.

Mr. Petersen, the managing director of Marine Harvest in Chile, said the company planned to return to the Lakes region in a few years, once the area had become free of contamination. In the longer term, he said, Marine Harvest will leave Chile’s fresh-water lakes and produce more older salmon in closed systems where it can maintain “biological control.”

Meanwhile, neighboring fishermen who have been affected by the fish-farming industry can only hope for better days. Mr. Guttierrez, 33, said that just six years ago he and his fishing partner would haul in 1,100 pounds of robalo on a typical day. On a recent day he pointed to that morning’s catch of only 88 pounds in a cooler in the bed of a pickup truck.

He lamented the changes he had observed in the fish: they are rosier than before, and their skin is flabbier. He said he suspected that the wild fish were eating the same food pellets that the salmon were being fed, which he said were falling to the sea floor.

“If the water continues to be contaminated, we will simply have to go to another area to find our fish,” he said. “But it is getting harder and harder.”