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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Marine Megafauna
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1394695

Bryde's whales produce Biotwang calls, which occur seasonally in long-term acoustic recordings from the central and western North Pacific

Provisionally accepted
Ann N. Allen Ann N. Allen 1*Matt Harvey Matt Harvey 2Lauren Harrell Lauren Harrell 3Megan Wood Megan Wood 4Angela R. Szesciorka Angela R. Szesciorka 5Jennifer L. McCullough Jennifer L. McCullough 1Erin M. Oleson Erin M. Oleson 1
  • 1 Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States
  • 2 Google (United States), Mountain View, California, United States
  • 3 Google, Inc., Boulder, CO, United States
  • 4 Saltwater Inc, Under Contract to NOAA Pacific Islands Fisheries Science Center, Honolulu, HI, United States
  • 5 Hatfield Marine Science Center, Oregon State University, Newport, Oregon, United States

The final, formatted version of the article will be published soon.

    In 2014, a novel call was discovered in autonomous acoustic recordings from the Mariana Archipelago and designated a “Biotwang”. It was assumed to be produced by a baleen whale, but without visual verification it was impossible to assign a species. Using a combination of visual and acoustic survey data collected in the Mariana Archipelago, we determined that Biotwangs are produced by Bryde’s whales. Bryde’s whales occur worldwide in tropical and warm temperate waters, but their population structure and movements are not well understood. Genetic and morphological data recognize two populations in the western North Pacific (WNP), separate from those elsewhere in the Pacific. We used a combination of manual and machine learning annotation methods to detect Biotwangs in our extensive historical passive acoustic monitoring datasets collected across the central and western North Pacific. We identified a consistent seasonal presence of Biotwangs in the Mariana Archipelago and to the east at Wake Island, with occasional occurrence as far away as the Northwestern Hawaiian Islands and near the equator (Howland Island). The seasonal occurrence of Biotwangs is consistent with Bryde’s whales migrating between low and mid-latitudes, with a small peak in calling between February and April and a larger peak between August and November as the whales travel past the recording sites. Our results provide evidence for a pelagic WNP population of Bryde’s whales with broad distribution, but with seasonal and inter-annual variation in occurrence that imply a complex range most likely linked to changing oceanographic conditions in this region.

    Keywords: Bryde's Whale, Passive acoustic monitoring, Deep machine learning, Seasonal occurrence, western North Pacific, Mariana archipelago, long-term monitoring

    Received: 01 Mar 2024; Accepted: 05 Aug 2024.

    Copyright: © 2024 Allen, Harvey, Harrell, Wood, Szesciorka, McCullough and Oleson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Ann N. Allen, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, HI 96818, Hawaii, United States

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