For 60 Years, an Eerie Quack Sounded Across the Seas. Scientists Just Found Its Source.
Since the 1960s, a strange, repetitious quacking noise called a “bio-duck,” which can frequently be heard in the Southern Ocean, has puzzled marine biologists and underwater acoustic experts.
A new study suggests that whatever animal is producing these sounds (possibly an Antarctic minke whale) is behaving like a back-and-forth conversation.
If true, this could provide a compelling piece of a data for further study of what is already a hard-to-research baleen whale.
The ocean is an endless source of mysteries—areas of deep ocean wait to be explored, species unknown to humanity meander its waters, and our understanding of its impact on the Earth’s geologic process is always a work-in-progress. However, one of the more strange mysteries of the deep is a “quack.”
First described by submariners in the 1960s, the strangely repetitious quacking sound in the Southern Ocean earned the nickname “bio-duck,” and researchers first recorded the phenomenon in 1982 while creating a soundscape of the South Fiji Basin. The mysterious sounds were described as four bursts of quack-like noises. Four years later, University of Victoria’s Ross Chapman, an expert in underwater acoustics, joined the project in an attempt to identify what these strange oceanic quacks could be. Although some sort of animal sound would be the most likely candidate, the eerily precise repetition of the quacks seemed almost non-biological.
“The sound was so repeatable, we couldn’t believe at first that it was biological,” Chapman, who recently reported the results of this sound at the 187th Meeting of the Acoustical Society of America earlier this month, said in a press statement. “But in talking to other colleagues in Australia about the data, we discovered that a similar sound was heard quite often in other regions around New Zealand and Australia.”
The leading theory, supported by evidence in a study led by scientists at the National Oceanic and Atmospheric Administration (NOAA), suggests these “bio-duck” signatures originate from the Antarctic minke whale (Balaenoptera bonaerensis). However, scientists have yet to directly observe a minke whale producing these sounds in real time. Minke whales, a kind of baleen whale, are difficult to study because they prefer icy waters, which are not easily accessible by ships. Previous studies have attempted to piece together how the Antarctic minke whale’s song operates, but it’s among the last of whale songs to be decoded.
Whatever animal may be producing these sounds, Chapman’s aim was to understand the biological function of the “bio-duck” sound. Chapman and his team recorded these sounds using an acoustic antenna, which is essentially an array of hydrophones towed behind a ship.
“We discovered that there were usually several different speakers at different places in the ocean, and all of them making these sounds,” Chapman said. “The most amazing thing was that when one speaker was talking, the others were quiet, as though they were listening. Then the first speaker would stop talking and listen to responses from others.”
This is the first evidence that these “bio-duck” sounds could be a conversation among different minke whales, and even Chapman can’t help but wonder what was the topic of their quack-like conversation.
“Maybe they were talking about dinner,” Chapman says, “maybe it was parents talking to children, or maybe they were simply commenting on that crazy ship that kept going back and forth towing that long string behind it.”
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