In a recent breakthrough, oceanographers and marine biologists have identified mysterious sounds recorded in the Pacific Ocean as the vocalizations of Bryde's whales, with the aid of a new AI application developed by Google. These sounds, known as "biotwangs," were first detected in 2014 during acoustic surveys in the Mariana Archipelago. The unusual, metallic calls puzzled scientists for years, as they were assumed to be the work of an unidentified species of baleen whale.
As detailed in a study published in Frontiers in Marine Science, the research team from NOAA’s Pacific Islands Fisheries Science Center and Oregon State University used both visual and acoustic surveys to confirm that the biotwangs were indeed produced by Bryde’s whales. Bryde’s whales are elusive creatures, residing primarily in tropical and warm temperate waters. Their population structure and movements, especially in the western North Pacific, remain poorly understood.
By combining visual observations with acoustic data, the researchers were able to directly link the biotwang sounds to sightings of Bryde's whales. Over two survey periods in 2018 and 2021, acoustic devices were deployed in the waters around the Mariana Islands, where Bryde's whales were observed. These devices, known as sonobuoys, recorded biotwangs during nine of the whale sightings, conclusively identifying them as the source of the mysterious sound.
Sound Audio File Here: "Western Pacific Biotwang." Credit: Oregon State University, Sharon Nieukirk
In addition to manual acoustic monitoring, the researchers employed machine learning techniques to analyze vast datasets of passive acoustic recordings collected across the central and western North Pacific. This combination of deep learning and manual annotation enabled them to detect biotwangs in historical acoustic recordings from multiple locations, including the Mariana Archipelago, Wake Island, and the Northwestern Hawaiian Islands.
The seasonal patterns of the biotwang calls also provided valuable insights into the whales' migration behaviors. Biotwangs were more frequently recorded between August and November, suggesting a migratory pattern between low and mid-latitudes. Additionally, a smaller peak in biotwang activity was observed between February and April, further indicating that these whales follow a complex migration route, possibly influenced by oceanographic conditions and prey availability.
This groundbreaking research not only solves a two-decade-old mystery but also demonstrates how AI can revolutionize the study of marine life. The ability to automatically detect and track whale populations through their vocalizations opens new possibilities for understanding the distribution, behavior, and conservation needs of these majestic creatures. As climate change continues to affect ocean ecosystems, the use of AI-driven technologies could prove crucial in monitoring and preserving endangered marine species like Bryde's whales.
More information: Ann N. Allen et al, Bryde's whales produce Biotwang calls, which occur seasonally in long-term acoustic recordings from the central and western North Pacific, Frontiers in Marine Science (2024). DOI: 10.3389/fmars.2024.1394695
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