Bomb Detectors Helped Discover a New Population of Blue Whales in the Indian Ocean


Jun 11, 2021


Image Credit: Franco Banfi

Scientists used the monitoring system in bomb detectors to discover a new population of pygmy blue whales, a subtype of the blue whales found in the Indian and the southern Pacific Ocean, according to a new study.

Published in Nature’s Scientific Reports, the study explains how a group of scientists found an entirely new population of blue whales relying on data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) — an international body that monitors international nuclear bomb testing — to detect the whales’ existence.

Each population of blue whales has a unique, signature song. Researchers identified the new population when the CTBTO-microphones picked up the song of this population. After analyzing the song’s structure, frequency, and tempo, scientists concluded that while the song was typical of pygmy blue whales — it didn’t resemble any song previously recorded in the region.

“I think it’s cool that the same system that keeps the world safe from nuclear bombs is available to researchers and allows a host of scientists, including us, to do marine science that would not be possible without such sophisticated [technology],” Tracey Rogers, a marine ecologist at the University of New South Wales (UNSW) in Australia, who co-authored the study, said in a statement.

Pygmy blue whales are the smallest recognized subspecies of blue whales. Nonetheless, since they are, after all, a subspecies of blue whales — the largest living animals — the pygmy blue whale is 24 meters’ long, almost the length of two buses together. However, that doesn’t make it easier to find the whales; they’re not only reclusive by nature, but also cover vast areas of oceans. “Blue whales in the Southern Hemisphere are difficult to study because they live offshore and don’t jump around — they’re not show-ponies like the humpback whales,” Rogers says.

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According to the International Union for Conservation of Nature’s Red List, the blue whale is presently endangered. The biggest threats to its life are vessel strikes, entanglement in fishing gears, and climate-related concerns. “They were brought to the edge of extinction by industrial whaling and they are recovering very slowly,” Emmanuelle Leroy, a postdoctoral fellow at UNSW, who led the study, told LiveScience.

At present, between 5,000 to 10,000 blue whales exist in the Southern Hemisphere; before whaling practices were common, their cumulative population size was about 350,000.

With the current discovery, the number of populations of pygmy blue whales in the Indian Ocean has gone up to five. The fourth population was discovered last December. “Finding a new population of pygmy blue whales in the Southern Hemisphere is exciting — it increases the global population that we did not realize was there before,” Rogers added.

However, the researchers were not been able to draw an exact estimate of the number of whales this group could have. Based on the number of calls that were picked up by the bomb detectors though, Rogers suspects “it’s a lot.”

At present, the researchers are hoping to add another layer of confirmation to their findings through visual sightings as well.

“We are still discovering missing populations of the largest animal that has ever lived… It’s a testament to the difficulty of studying life in the ocean,” Rogers noted.


Written By Devrupa Rakshit

Devrupa Rakshit is an Associate Editor at The Swaddle. She is a lawyer by education, a poet by accident, a painter by shaukh, and autistic by birth. You can find her on Instagram @devruparakshit.


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