### The Enigma of the “Biotwang”: How Machine Learning Aided in Uncovering a Unique Whale Call
In 2014, researchers sifting through acoustic data from the Mariana Archipelago encountered an enigmatic sound that baffled them. It was a whale call, yet it differed from any previously recorded. This vocalization contained both low and high-frequency elements, and its mechanical tone suggested it was more akin to something artificial—perhaps a naval vessel—than a living creature. The call was so remarkable that it was dubbed the “biotwang.”
For several years, the source of the biotwang eluded explanation. However, with the help of advancements in machine learning and acoustic analysis, scientists have now pinpointed its origin. A recent publication in the journal *Frontiers in Marine Science* indicates that the biotwang comes from a species of baleen whales called Bryde’s (pronounced “broodus”) whales. This finding not only clarifies a long-standing enigma but also paves the way for enhanced tracking and examination of these enigmatic animals.
#### The Function of Passive Acoustic Monitoring
Marine biologists have traditionally depended on passive acoustic monitoring (PAM) to gather enduring data on the ocean’s soundscape. This method involves deploying underwater microphones, known as hydrophones, to record underwater sounds, including whale calls. PAM is particularly valuable for observing marine mammals like whales, which can be hard to spot visually because of their extensive migratory pathways and the deep, remote habitats they inhabit.
Calls from whales are species-specific and can even vary among distinct populations within a species. By scrutinizing these vocalizations, researchers can extract critical information about whale behaviors, population dynamics, and migratory trends. Bryde’s whales, specifically, are recognized for their regionally tailored calls. In the eastern North Pacific, their calls usually remain under 100 Hz, with harmonic frequencies reaching as high as 400 Hz. Yet, considerably less is understood about the vocalizations of Bryde’s whales in the western and central North Pacific, where only a few instances had been noted prior to the identification of the biotwang.
#### The Unveiling of the Biotwang
The biotwang was initially discovered in 2014 during an acoustic survey of the Mariana Archipelago, a secluded area in the western Pacific Ocean. The call was notable for its extraordinary structure. It comprised a complex, multi-phase sound lasting approximately 3.5 seconds. The call began at a low frequency around 30 Hz and concluded with a high-pitched, metallic sound that peaked at 8,000 Hz. This broad frequency spectrum, along with the call’s unique mechanical character, distinguished it from any other known whale vocalizations.
“It’s a truly strange call,” commented Ann Allen, a scientist at NOAA Fisheries and co-author of the research. “Anyone unfamiliar with whale sounds would assume it originated from some type of artificial source, like a naval vessel.” The researchers who first detected the biotwang were well-versed in whale sounds and suspected it belonged to a baleen whale. Nevertheless, since the survey was carried out autonomously without visual verification, they could not ascertain the source of the call.
#### Machine Learning Steps In
To unravel the mystery of the biotwang, a different group of scientists employed machine learning techniques. They constructed a model capable of analyzing extensive datasets of whale vocalizations across various species. By contrasting the biotwang with established whale calls, the model facilitated the identification of potential sources. The researchers then integrated this acoustic scrutiny with visual observations of whale behavior, ultimately confirming the source of the biotwang as Bryde’s whales.
This advancement carries significant implications. Firstly, it offers new methods for monitoring Bryde’s whale populations, especially in areas where their calls are not well documented. Secondly, it underscores the promise of machine learning in the exploration of marine life, particularly in scenarios where traditional observational techniques are difficult or unfeasible.
#### The Significance of Comprehending Whale Vocalizations
Whale vocalizations are not merely arbitrary sounds; they perform essential biological functions. Whales utilize calls for communication with peers, navigating their surroundings, and locating mates. Grasping these vocalizations can shed light on whale behavior, social dynamics, and even their reactions to environmental alterations, such as changes in ocean temperatures or the impacts of noise pollution from human activities.
Studying Bryde’s whales is especially challenging due to their common presence in remote, tropical, and subtropical marine regions. They are also notably mobile, traversing vast distances. By identifying and cataloging their vocal patterns, researchers can enhance the monitoring of their movements and population health. This initiative is crucial in terms of conservation, as numerous whale species contend with threats like ship collisions, entanglement in fishing gear, and habitat loss.
#### The Horizon of Whale Research
The identification of the biotwang as a call from Bryde’s whales exemplifies how technological advancements can aid
