A one-of-a-kind killer whale population appears to be threatened by human appetites for Antarctic toothfish, better known to restaurant-goers as Chilean Sea Bass.

As fishing fleets patrol their waters, catching what was their primary source of food, the whales are vanishing. It’s not certain whether they’ve only moved on, or are dying out, or both. But something is happening, with potentially dark implications for Earth’s last pristine ecosystem.

“There’s been a dramatic disappearance of the whales,” said biologist David Ainley of ecological consulting firm H.T. Harvey and Associates, and co-author of a March Aquatic Mammals article on the whales’ disappearance. “We think they’re having a harder time trying to find food. Whether that leads to population decrease, hopefully we won’t find out. But we will find out, if it continues.”

Antarctic killer whales form two types of populations, known to researchers as ecotype-B and ecotype-C. While the former resemble killer whales found elsewhere, ecotype-C whales are much smaller, with different markings and a tendency to gather in especially large groups. Many researchers now consider them a distinct species.

Dubbed Ross Sea killer whales, ecotype-C whales are found only in the Ross Sea, an expanse of water off Antarctica’s southern coast, flanking the France-sized Ross Ice Shelf. Many scientists consider the region to be the last pristine ecosystem on Earth, the only remaining piece of pre-industrial nature.

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