Scientists have recently discovered a whole new population of giant blue whales in the Indian Ocean. These whales have managed to remain undetected for decades despite their huge size.
Researchers found these secretive mammals by examining data that was collected for an underwater nuclear bomb detection array. The team was taken aback after they heard a unique song that they had never heard before. In general, blue whale songs are long and have a low frequency – which is below what humans are capable of hearing. Each song is unique in itself.
About these species
The giant blue whales (Balaenoptera musculus brevicauda)- although they are a smaller version of a blue whale that reaches a maximum length of 79 feet. They have been named after a group of islands in the Indian Ocean which is near the group’s lair.
A senior author, Tracey Rogers, who is a marine ecologist at the University of New South Wales (UNSW) in Australia, told Live Science that they were still discovering the missing populations of one of the largest animals that has ever lived on Earth. They added that this case was a witness to the difficulty in studying life in the ocean.
According to lead author Emmanuelle Leroy, a postdoctoral fellow at UNSW, told Live Science that finding blue whales is generally very difficult and that they were thought to be almost extinct.
According to the Center for Biology Diversity, there are currently 5,000 to 10,000 blue whales that exist in the Southern Hemisphere, as compared with the pre-whaling population where there are still 350,000. The remaining who are left often choose to remain solitary and are spread across large geographic areas, making them easy to miss.
Leroy stated that the best way to study them was by using passive acoustic monitoring.
How were they discovered?
When it comes to the Indian Ocean, there are limited scientific acoustic arrays set up. So the team turned to underwater nuclear bomb detectors belonging to the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) — it is an international group that uses a global underwater auditory relay network to detect illegal nuclear bomb tests in the oceans. This in turn gave the researchers access to a long-term dataset of noises across the Indian Ocean. After analysing the data, the researchers narrowed down on a blue whale song that had not been heard before.