A group of submariners returned from the Southern Ocean with a strange story that they had heard the ocean quack.
Strange enough as it was, it turned out not to be a one-time event either.
The strange quack sound became a widespread topic and quickly earned itself the name 'bio duck'.
In the 1980s, a team of researchers mapping the sounds of the South Fiji Basin recorded four bursts of quack-like noises.
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Four years into the project in 1986, Ross Chapman from the University of Victoria joined the project and described their scepticism in a statement: "We discovered that the data contained a gold mine of new information about many kinds of sound in the ocean, including sounds from marine mammals."
Commenting on the bizarre sound, he added: "The sound was so repeatable, we couldn't believe at first that it was biological."
After consulting with Australian colleagues, they found similar sounds recorded in other locations near New Zealand and Australia.
Chapman now believes the quacks were conversations between sea creatures.
"Maybe they were talking about dinner, 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," he described.
That “crazy ship” was fitted with acoustic antennas and hydrophones which helped pinpoint where the sounds were coming from.
The unique design of the ship allowed the scientists to identify the direction the sounds were originating from which resulted in different directions all around the ship.
Chapman noticed the speakers almost took turns like people in a conversation.
“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,” Chapman noted.
Strangely, none of the animals making the sounds were actually visually identified.
"The most amazing thing was that when one speaker was talking, the others were quiet, as though they were listening,” said Chapman.
“Then the first speaker would stop talking and listen to responses from others."
Further evidence was gathered in 2014 from a study which found that the noise comes from the Antarctic minke whale.
Researchers believe the 'bio duck' noises' matched the frequency and pulse patterns of the whales’ calls.
In November this year, Chapman presented his findings at the 187th Meeting of the Acoustical Society of America.
“We discovered that the data contained a gold mine of new information about many kinds of sound in the ocean, including sounds from marine mammals,” he recalled at the meeting.