The mysterious sounds of the Pacific Ocean turned out to be whale songs

This unusual noise, known as "biotwang", turned out to be the sound signal of Bryde's whales. The study was published in the journal Frontiers in Marine Science.

The sounds were first recorded in 2014, and then their unique metallic tone immediately attracted the attention of scientists. The sound was named "biotwang" because of its unusual character. Since then, it has been recorded in different locations in the ocean, raising many questions. In 2016, scientists from Oregon State University suggested that the sound could be produced by a species of killer whale, but the exact identification remained a mystery.

A new study has confirmed that assumption: the mysterious sounds are indeed made by Bryde's whales. Researchers made the discovery while studying marine life around the Mariana Islands. They were able to record several sightings of these rarely seen whales and simultaneously record a "biotwang" using underwater microphones. These synchronised observations and recordings allowed the scientists to confidently link the sound to Bryde's whales.

To investigate further, the researchers teamed up with a team from Google that was developing artificial intelligence to recognise whale vocalisations. After much training, the AI-based app learned to recognise the sounds of eight whale species, including Bryde's whales, and even track their movements.

The results from the app showed that Bryde's whales not only live off the Mariana Islands, but also spend a lot of time in the transitional zone of the Pacific Ocean, an area where warm and cold waters meet, which favours the growth of plankton populations, the whales' main food source.