Maxing out at around 200 tons, the blue whale is not only the largest animal on the planet, it is also the largest animal ever to exist. These creatures become so massive by eating a diet comprised almost entirely of krill, the translucent, thumb-sized organisms that thrive in the frigid waters of Antarctica.

Blue whales are baleen feeders: In place of teeth they have baleen plates, made from keratin, that serve as a sieve. Swimming toward huge concentrations of krill, they open their triple-hinged jaws to gulp in huge volumes of water and prey, then filter out the water. The only baleen whale that almost exclusively eats krill, blues can consume as much as 16 metric tons of the shrimp-like crustaceans in a day.

But this food supply appears to be faltering. In addition to supertrawlers, climate change, which is warming the oceans and melting polar ice, is causing large-scale changes in the Southern Ocean krill population, changing their distribution and behavior and in some places contributing to declines of as much as 80 percent. Parts of Antarctica are warming five times faster than the global average. Last fall the British Antarctic Survey warned that “dramatic and extreme changes in Antarctica are happening faster than expected,” and the continent could be approaching a tipping point.

“Our calculations suggest we might harvest krill to the point where we do real damage to recovering whale populations.”

Now another possible threat to krill populations is worrying researchers and conservationists, supertrawlers. The crustacean’s massive concentrations in the Antarctic have attracted supertrawlers from around the world that vacuum up to 1,000 tons of krill a day, then process the animals onboard into krill oil. Rich in omega-3 fatty acids, the oil is used in human nutritional supplements, as food for aquaculture, and in pet food.

Thanks to technology that allows large-scale harvesting, the business began to take off about 15 years ago and is now booming. Last October, Norway began lobbying the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which manages the krill fishery, to double the allowable take in the Southern Ocean. The krill industry is worth as much as $900 million annually.

Read the full article about supertrawlers reducing krill populations by Jim Robbins at Yale Environment 360.