'Bizarre' Mariana Trench sound likely linked to whales, but no less mysterious
The Western Pacific Biotwang is probably the work of dwarf minkes, but what they're saying is not at all clear.
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It comes from one of the planet’s most forbidden places and it has a fantastic name, but a mysterious sound’s origin might not live up to some of the wilder speculation.
Since 2014, the “Western Pacific Biotwang” has been repeatedly picked up during exploration of the Mariana Trench and scientists have been puzzled by its bizarre mix of pitches, alternately sounding biological and computer-generated.
However, researchers at Oregon State University have settled on a decidedly biological guess by tracing the likely source to whales – but that doesn’t mean the mystery is solved.
“It’s very distinct, with all these crazy parts” said Sharon Nieukirk, a senior faculty research assistant of marine bioacoustics at OSU. “The low-frequency moaning part is typical of baleen whales, and it’s that kind of twangy sound that makes it unique.”
The team determined the sound closely resembled the so-called “Star Wars” vocalizations made by dwarf minke whales near Australia’s Great Barrier Reef, but what the animals are communicating via the unusual new call is still unknown.
Dwarf minkes are the smallest species of baleen whale and are quite elusive, making their homes in areas prone to rough seas and surfacing only for “an inconspicuous blow.”
However, the whales are very vocal and their frequent calls to one another allow them to be easily monitored for acoustic studies.
“If it’s a mating call, why are we getting it year round? That’s a mystery,” wondered Nieukirk. “We need to determine how often the call occurs in summer versus winter, and how widely this call is really distributed.”
Accomplishing that is easier said than done, however. Researchers tend to keep such searches to narrow frequency ranges, a tactic that helps filter out unrelated ocean sounds but also runs the risk of missing portions of the Biotwang, which has a very wide range.
Of course, all this is assuming that it’s actually the dwarf minkes that are singing the twang. As of now, the OSU team is only saying that is their best guess.
“Our hope is to mount an expedition to go out, find the animals and find out exactly what’s making the sound,” Nieukirk said.
“It really is an amazing, weird sound, and good science will explain it.”