Humpback whale calls reveal mysterious gunshot sound

A team of researchers from the University of Exeter in UK and Stellenbosch University in South Africa has recorded sounds made by humpback whales at the Vema Seamount in the Atlantic Ocean, a few hundreds of miles west of the South African coast. The recordings revealed a variety of calls, including an “impulsive sound” – dubbed “gunshot” by the scientists – that has never been recorded before.

The researchers used moored hydrophones deployed during the Southern Hemisphere spring of 2019 to record the whales’ calls. These calls were detected during a period of 11 days, and were categorized into continuous “song” and shorter “non-song” calls.

Among the over 600 non-song calls recorded, the most common one was a low “whup,” which is known to be used between mothers and calves to help them locate each other. Occasionally though, whales also “whup” while feeding. Other sounds included “grumble” calls – which are also emitted by whales while feeding – as well as a more mysterious “gunshot” call, whose significance is still unknown.

“We still don’t fully understand what the “gunshot” call means, and it is fantastic to record it in humpback whales for the first time,” said study co-author Dr. Kirsten Thompson, a population biologist at the University of Exeter. “It really shows how much we still have to learn about these incredible animals.”

According to Dr. Thompson, the “whup” and “grumble” calls confirm that the whales passing through the Vema Seamount during their long migration to the polar regions are feeding. “Seamounts can provide rich habitat for all sorts of migratory species and we urgently need widespread protection of the global oceans to ensure these habitats can persist.”

Although the area around the Vema Seamount was heavily overfished after its discovery in 1959, it is now closed for fishing and recognized as a vulnerable marine ecosystem in need of protection due to its unique biodiversity. However, no legally binding international agreement exists to protect the network of seamounts in the high seas.

“50 years ago, governments came together to turn around the fate of humpback whales. Now they have a chance to secure the progress already made and protect the high-seas habitats that whales rely on. While such large areas of our oceans remain unprotected, these ecosystems are highly vulnerable. A coherent and connected network of Marine Protected Areas (MPAs) across our oceans is urgently needed to ensure seamounts like Vema are protected,” concluded Dr. Thompson.

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By Andrei Ionescu, Earth.com Staff Writer