Arabian Sea Humpback Whales Sing Simplified Versions of Whale Calls: Study

Arabian Sea humpback whales could be singing a more simplified version of their calls compared to humpback whales in other parts of the world, according to a new study.

Humpback whales in the Arabian Sea are geographically and genetically isolated from other whale populations. The subpopulation of these whales have been listed as endangered by the International Union for Conservation of Nature (IUCN). Unlike other humpback whales, Arabian Sea humpback whales do not migrate and they remain in tropical waters all year.

For decades, scientists have studied humpback whales' singing. But very little is known about how they function. All singing members in the same area of the ocean sing the same song, and when the song changes, all members switch to the new song. The males sing complex songs that can last up to 20 minutes.

Now, a team of researchers has found that the humpback subpopulation in the Arabian Sea is singing a simplified version of the whale calls compared to whales elsewhere.

For their study, the research team used hydrophones (underwater microphones) to record the whales' songs and compare it with the calls made by whales in other places. They found that the humpback whales in the Arabian Sea produced phrases, formed of sequences of notes, "which they then might be joining into regular and repeatable patterns," Robert Baldwin, scientist at the Environment Society of Oman's Whale and Dolphin Research Group, told BBC.

"This would be like song, except that everywhere else in the world, song is composed of themes, which are repeated phrases," he said.

It is not clear as to why these Arabian Sea humpback whales make simple calls, but Baldwin speculates it could be because of their isolation from other populations. Moreover, the population of this Arabian Sea humpback whales is very small (around 100 whales exist), which allows the whales to get exposed to less variations in their song.

Researchers are further planning to examine the recordings to understand the intention behind the whales' simplified calls.