The Bio-duck
Later explainedSummary
For fifty years, submariners in the Southern Ocean heard quacking.
A repetitive, mechanical, low-frequency sound, in trains of pulses, coming from somewhere in the dark under the ice. It sounded so much like a duck that they called it the bio-duck, and it became one of the most commonly recorded sounds in the Southern Ocean, and nobody had any idea what was making it.
It was a whale.
The reason it took half a century to work out is not that anybody was stupid. It is that nobody had put a microphone on the whale.
What is documented
The sound. A repetitive series of low-frequency pulses, in a distinctly rhythmic pattern. Submarine crews operating in the Southern Ocean began reporting it in the 1960s, and the name they gave it stuck.
Its ubiquity. As hydrophone monitoring of the Southern Ocean expanded, the bio-duck turned out to be everywhere. It is one of the most frequently recorded sounds in those waters, and it is seasonal: heard predominantly in winter and spring.
The candidates. Over the decades it was attributed to submarines, to ice, to fish, and to any number of things. None of it was confirmed, because nothing was ever caught making the noise.
The tags. In February 2013, Denise Risch and colleagues attached acoustic recording tags directly to Antarctic minke whales, Balaenoptera bonaerensis, off the Western Antarctic Peninsula.
The tags recorded what the whales were doing and what they were saying at the same time.
The whales made the bio-duck.
The result was published in Biology Letters in April 2014.
Leading explanations
The Antarctic minke whale. Settled.
The identification is direct, not inferential. A recorder was attached to an animal, the animal produced the sound, and the recorder recorded it. There is no chain of reasoning to dispute.
Why it mattered beyond itself. This is the part that makes the record worth keeping.
The Antarctic minke whale is very hard to survey. It is comparatively small for a baleen whale, it spends much of its life among sea ice, and visual surveys of the Southern Ocean in winter are difficult, dangerous and expensive.
The bio-duck is loud, distinctive, and everywhere. Now that it is known to belong to the minke whale, it is a tool: fifty years of accumulated hydrophone recordings, and every future recording, can be used to map where these animals are and when.
An unsolved noise became a census.
What the popular version gets wrong
"It was a mysterious unexplained sound." It was an unexplained sound, which is not the same as a mysterious one. Nobody who worked on it thought it was anything but an animal or a machine. What they lacked was not an idea. It was a measurement.
"It took fifty years because the sound was so strange." It took fifty years because for most of that period the technology to attach a recording device to a wild minke whale under Antarctic sea ice did not exist, and when it did exist somebody had to go and do it, in the Southern Ocean, in a small boat.
The delay was logistical, not intellectual.
"Another ocean mystery solved." The ocean is enormous, mostly dark, and largely unmonitored. Almost every sound coming out of it that nobody has identified is an animal, or ice, or a ship, and the reason it is unidentified is that nobody has been there to look.
Current status
Later explained. The source is identified, the identification is direct, and the sound is now a research instrument.
The registry keeps this record beside AR-0004 and AR-0005 as the third of a set, and the set makes a point together.
The Bloop was ice, and NOAA said so early, and the internet built a monster anyway. The bio-duck was a whale, and the answer required somebody to go and stick a recorder on one. The 52-hertz whale is still unidentified, and it will stay unidentified until somebody sees it.
Every one of these was solved, or will be solved, by the same method. Go to the place. Put an instrument on the thing. There is no other way, and there never has been.
Sources
- Risch, D., Gales, N. J., Gedamke, J., Kindermann, L., Nowacek, D. P., Read, A. J., Siebert, U., Van Opzeeland, I. C., Van Parijs, S. M. and Friedlaender, A. S. (2014). "Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)." Biology Letters 10, 20140175.
- Acoustic recording tags deployed on Antarctic minke whales, Western Antarctic Peninsula, February 2013.
- Historical submarine and hydrophone reports of the bio-duck from the 1960s onward.
Last reviewed: July 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.