The enigmatic sound recorded deep in the ocean, known as "biotwang," has finally been traced back to a fascinating source: the Bryde's whale (Balaenoptera brydei). First documented in 2014 in the western Pacific, this sound travels long distances across the open ocean.
Research led by Ann Allen from the Pacific Islands Fisheries Science Center, part of NOAA, reveals that the Bryde's whale inhabits warm tropical and temperate waters worldwide, yet their population structure and movements remain poorly understood.
Findings indicate a pelagic population of Bryde's whales in the North West Pacific, showing seasonal and interannual variations likely influenced by changing oceanographic conditions.
Initially recorded in the Mariana Islands during an autonomous sound study by Oregon State University, biotwangs were linked to the presence of Bryde's whales during a NOAA study in 2018, where researchers observed ten whales and noted biotwangs associated with nine of them.
Despite the challenges of studying the ocean, NOAA has been monitoring marine mammal sounds for over two decades, utilizing passive acoustic recorders to detect populations in remote areas.
With the help of artificial intelligence developed in collaboration with Google, researchers can now analyze vast amounts of data in hours rather than years, identifying a consistent seasonal presence of biotwangs in the Mariana Islands and Wake Island.
This suggests that the biotwang may be a specific call of a Bryde's whale population in the North West Pacific. The seasonal occurrence aligns with the whales' migration patterns, peaking between February and April, and again from August to November.
The distinct calls of this population could represent a dialect not used by any other recorded Bryde's whale populations. Understanding the source of these sounds provides researchers with a new tool to track and comprehend the distribution and migration patterns of Bryde's whales globally.
Scientists hope this information will aid in finding ways to protect these magnificent creatures that inhabit the world's mysterious oceans.