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Pygmy blue whales

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Pygmy blue whales

Tue, 08/06/2021 - 12:28
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A new population of pygmy blue whales has been discovered in the Indian Ocean, thanks to the recordings of underwater nuclear bomb detectors.

The pygmy blue whale is the smallest subspecies of the blue whale (shown here).
The pygmy blue whale is the smallest subspecies of the blue whale (shown here).

A new population of pygmy blue whales has been discovered in the Indian Ocean, thanks to underwater nuclear bomb detectors that recorded their whale songs.

The research team, led by the University of New South Wales (UNSW), had been studying data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) which monitors international nuclear bomb testing, when an unusually strong signal caught their attention.

It was a whale song, but one that the scientists knew little about. Studying its structure, frequency and tempo, they realised that the whale songs came from a group of pygmy blue whales that had not been previously recorded in the area before.

The team then scanned through all of the CTBTO data—18 years’ worth—looking for any wider patterns and confirmed that the songs were not a random occurrence.  

Lead author Emmanuelle Leroy, a UNSW postdoctoral fellow, said that the songs of blue whales were very structured and simple, but each subspecies and population had a different song type. “Their songs are like a fingerprint that allows us to track them as they moved over thousands of kilometers,” she said.

The Chagos whale song has three sections: the first was the most complex, and this was followed by two basic parts.

"This new whale song has been a dominant part of the soundscape in the Central Equatorial Indian Ocean for the past nearly 18 years," said senior author Tracey Rogers, a UNSW marine ecologist, in a Live Science article. 

"We found them not only in the central Indian Ocean, but as far north as the Sri Lankan coastline and as far east in the Indian Ocean as the Kimberley coast in northern Western Australia,” she added.

At this time, the Chagos population has yet to be confirmed with a visual sighting.

The findings of their study has been published in the Scientific Reports journal.

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