Scientists Discover Population of Incredibly Rare Whales With the Help of Nuclear Bomb Detectors

While blue whales are the biggest marine animals in existence, they're notoriously elusive. But scientists at the University of New South Wales (UNSW) in Australia believe that that they have discovered a brand new population in the central Indian Ocean.

The new population is comprised of an unknown number of pygmy blue whales. Pygmy blue whales, as their name would suggest, are the smallest subspecies of blue whales. In this context, however, "small" is a relative term. Their beefier relatives might dwarf them by dozens of inches and pounds, but pygmy blue whales can still reach 24 meters (about 79 feet). That's nearly the length of two standard buses, according to the UNSW Newsroom.

"We don't know how many whales are in this group, but we suspect it's a lot by the enormous number of calls we hear," Tracey Rogers, a professor at UNSW and a senior author of the study, told the newsroom.

Rogers and colleagues published their analysis in the scholarly journal Scientific Reports on April 22. If visual observations confirm their conclusions, the new population of pygmy blue whales would be the fifth to be identified in the region, according to the newsroom.

Blue whales breach off the California coast.
A rare blue whale breaches off the California coast. A new population of a smaller subspecies, the pygmy blue whale, has been discovered in the central Indian Ocean. David McNew/Getty Images

Rogers and colleagues were reviewing data collected by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), a collective that was formed in 1996 to monitor nuclear bomb testing when their suspicions were aroused. One of the most utile weapons in the CTBTO arsenal is the hydrophone, a sophisticated piece of technology that essentially functions as an underwater microphone. Hydrophones record the soundwaves created by nuclear bomb tests, but they also pick up many other noises, including those made by marine animals.

During their review, Rogers and colleagues heard a whale song that differed from the ones sung by the three populations of blue whales and the four populations of Omura's whales known to inhabit the area. Far from being interchangeable, whale songs are unique in such sonic characteristics as tempo, structure and frequency, according to the newsroom.

"We still don't know whether they're born with their songs or whether they've learnt it," Rogers said. "But it's fascinating that within the Indian Ocean you have animals intersecting with one another all the time but whales from different regions still retain their distinctive songs. Their songs are like a fingerprint that allows us to track them as they move over thousands of kilometers."

Marine biologists estimate that less than 0.15 percent of blue whales in the Southern Hemisphere survived the whaling age. Their numbers, Rogers said, are still recovering.