Blue Whales Have Gone Silent. Why That Has Scientists Worried About Earth’s Biggest Animals… And the Ocean

Blue whales — the largest animals on Earth — aren’t singing as much anymore, and that’s got scientists concerned.

A study published in PLOS analyzing six years’ worth of acoustic data collected from the ocean’s floor found that blue whale vocalizations have been decreasing as the animal’s food sources have disappeared.

The monitor — a hydrophone sitting on the sea floor off the coast of California — collected sounds from the various creatures in the ocean, including multiple whale species.

By coincidence, the recordings began during a marine heatwave that is unprecedented in modern times. According to the study, the heatwave reduced the amount of krill available for blue whales to consume. As the krill disappeared, so too did the blue whale songs.

Over the course of the acoustic collection, blue whale songs deceased by approximately 40 percent.