It all began when researchers discovered an odd sound in 2014 near the Mariana Trench, deep within the Pacific Ocean. The metallic, moaning tone of the sound baffled scientists. The enigmatic noise, called a “biotwang,” was once believed to come from a ship or naval action. But eventually, after years of research, scientists connected the sounds to the mysterious Balaenoptera brydei, or Bryde’s whale.
Large baleen whales known as Bryde’s whales filter-feed on fish and krill, but because they are always moving, it is challenging to see them. Now years later, by examining the biotwang noises in long underwater recordings, researcher Ann Allen of the National Oceanic and Atmospheric Administration (NOAA) saw the possibility of tracking these whales via passive acoustic monitoring. She collaborated with Google researchers to use artificial intelligence (AI) to sift through more than 180,000 hours of hydrophone data from the network of hydrophones in the Pacific Ocean maintained by NOAA.
Significant advancements were made by Google’s AI model, which was trained to recognise whale vocalisations by examining spectrograms, or visual representations of sound. Eight different whale species, including the Bryde’s whale, had their calls correctly identified by it. Researchers have gained fresh insights about Bryde’s whale behaviour because of the AI’s ability to identify the biotwang sound, especially in the western Pacific, where a particular group appears to generate these sounds most frequently.
The study also suggested that these whales may be tracking the transition zone chlorophyll front, which is a region rich in plankton and other food sources and where warm and cool waters converge. Changes brought about by more intense El Niño and La Niña occurrences may compel whales to migrate farther in search of food as climate change picks up speed, which could have an impact on their general health.
As climate change alters marine life’s habitats, this discovery highlights the value of technology in tracking down rare species and provides a fresh approach to monitoring them.