Scientists have discovered a whole new pygmy population Blue whale In the Indian Ocean, despite its huge size, it has been able to avoid detection for decades.
Researchers have discovered secret cetaceans by analyzing acoustic data collected by an underwater nuclear bomb detection array. This reveals a unique song that scientists have never heard of.
A new population of pygmy blue whales (Balaenoptera musculus brevicauda) —A smaller subspecies of the blue whale, up to 79 feet (24 meters) long — is now called the Chagos Archipelago after a group of Indian Ocean islands near the group’s hideout.
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Tracey Rogers, senior author and marine ecologist at the University of New South Wales (UNSW) in Australia, told Live Science: “It’s evidence of the difficulty of studying life at sea.”
“Blue whales are generally hard to find,” lead author Emmanuel Leroy and UNSW postdoctoral fellow told Live Science. “They are endangered by industrial whaling and recovery is very slow,” he said.
Currently, the Southern Hemisphere is home to about 5,000 to 10,000 blue whales, but the pre-whaling population is about 350,000. Biodiversity CenterThe remaining few are often lonely and spread over large geographic areas, making them easy to miss, Leroy said.
“The best way to study them is through passive acoustic monitoring,” Leroy said. “But this means that you need to record hydrophones in different parts of the ocean.”
Especially in the Indian Ocean, the installation of scientific acoustic arrays is limited. So the team turned to the Underwater Nuclear Test Ban Device, which belongs to the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). This is an international group that uses a global underwater acoustic relay network to detect illegal nuclear tests in the ocean. This gives researchers access to long-term data sets of noise throughout the Indian Ocean.
“CTBTO data is an important international asset,” Rogers said. “The same system that keeps the world safe from nuclear bombs is available to researchers, allowing many scientists, including us, to perform marine science that would not be possible without such a sophisticated underwater acoustic array. I think it’s great to do. “
After analyzing the data, researchers discovered a particular blue whale song that they had never heard before.
“The blue whale song is very simple in that it is a repeat of the same pattern,” Leroy said. “But the blue whale subspecies and populations have different song types.”
In general, blue whale songs are long, infrequent, and can be less than human ability. Hearing (Less than 20 Hz) — High intensity, repeated at regular intervals. However, different groups of whales have calls with different durations, structures, and numbers of individual sections.
Chagos songs belonging to the new pygmy group have three sections, the first section being the most complex, followed by two basic parts.
“This new whale song has been a dominant part of the Central Equatorial Indian Ocean soundscape for the past 18 years,” Rogers said. Due to the dissemination of songs, researchers are convinced that songs belong to a whole new group, not just a few lonely individuals. However, the exact size of this new population remains a mystery.
“Unfortunately, we don’t know the population of the pygmy blue whale,” Leroy said. “acoustic [surveys] We are unable to provide this information yet. “
“It’s exciting to find a new population of pygmy blue whales in the Southern Hemisphere,” Rogers said. “It increases the world’s population, which we were unaware of being there before.”
Visual identification is still needed to clearly confirm the existence of the Chagos Archipelago population, but researchers are convinced that this is only a matter of time.
In December 2020, Another study Using an acoustic survey co-authored by Rogers and Leroy, we discovered another new population of blue whales near Oman.
“This gives us an idea of the population of five pygmy blue whales in the Indian Ocean,” Rogers said, making the area a hotspot for subspecies.
These discoveries would have been “impossible” without acoustic research, Rogers said.
This study was published online in the journal on April 22nd. Science report..
Originally published in Live Science.
Nuclear bomb detector discovers a secret population of blue whales hiding in the Indian Ocean
Source link Nuclear bomb detector discovers a secret population of blue whales hiding in the Indian Ocean