In a purely economic sense, Chilean salmon farming in recent years has made astounding strides. Since the government began promoting development of the industry here in the mid-1980s, salmon has overtaken copper and wood products as Chile’s top export to the United States. Chile has captured more than half of the U.S. salmon market—and this year it is expected to surpass Norway as the world leader in farmed-salmon production.

All along, however, environmental questions have loomed. And over the past year they have cast a particularly menacing shadow. Last year, European health officials seized shipments of Chilean salmon on grounds the fish meat contained excessive concentrations of a banned fungicide, and Japanese health officials impounded Chilean salmon tainted with antibiotics.