The Antarctic Endeavour glides across the water’s silky surface as dozens of fin whales spray rainbows from their blowholes into a fairy tale icescape of massive glaciers.

But as a patrol of environmentalists approaches the Chilean super trawler in an inflatable boat, the cruder realities of modern industrial fishing come into view.

From one of the ship’s drain holes, a steaming pink sludge cascades into the frigid waters of the Southern Ocean. It’s the foul-smelling runoff from processing the 80-meter (260-foot) factory ship’s valuable catch: Antarctic krill, a paper-clip-sized crustacean central to the region’s food web and, scientists say, an important buffer to global warming.

“What’s coming out of the side are the remnants of the ecosystem,” says Alistair Allan, an activist for Australia’s Bob Brown Foundation, as he looks on from the inflatable boat. “If this was off the coast of Alaska, it would be a national park. But since it’s down here at the bottom of the world, where no one is watching, you have ships almost running into whales feeding on the same things they’re fishing.”

While krill fishing is banned in U.S. waters due to concerns it could impact whales, seals and other animals that feed on the shrimp-like creatures, it’s been taking place for decades in Antarctica, where krill are most abundant. It started in the 1960s, when the Soviet Union launched an industrial fleet of trawlers in search of an untapped protein source that could be canned like sardines.