There was an update in the Washington Post this weekend on the slow-motion environmental tragedy that is fish farming in Chile. Salmon isn’t native to Chile and neither are the fish farms—20 years ago, they hardly existed. But the American appetite for cheap salmon fillets has provided the capital for what’s now a massive Chilean industry. There’s a fair chance that any farmed salmon you see comes from Chile. (Charles Fishman, for his book on Wal-Mart, did some wonderful reporting last year on how exactly those fillets can be so cheap.)

The young salmon, or smolt, are raised in pens in Patagonia’s lakes before being moved to cages in the open ocean. That sounds easy enough. But the young salmon routinely escape their pens: As an invasive species, they’re disrupting the lakes’ ecosystem. The other problem is that the fish pellets dropped for the salmon sometimes fall uneaten to the bottom of the lakebeds. That raises the nutrient levels, which throws the ecosystem out of whack, accelerating algae and plankton growth and decreasing the oxygen available for fish. (Oxygen deficiency, or hypoxia, is the technical term for what’s happened in the Gulf of Mexico’s New Jersey–size dead zone, for which agricultural runoff, not fish food, is the cause.) The upshot is that, according to the World Wildlife Fund, “93 percent of native fish species in the lakes are classified as vulnerable or threatened, and 40 percent are considered endangered.”

Chile’s government has loose regulations for fish farming: An official at the National Environmental Trust says that “Norwegian seafood companies come to Chile and do things they’d never get away with at home.” The World Wildlife Fund has argued that smolt-raising operations should be conducted in “contained, land-based facilities” instead of lakes, and the Post says such systems are “already is use” in other countries, but in Chile, the paper can only cite a single company that’s moving toward them.

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