Unknown origin: 'Quack-like' sounds heard in the deep ocean remain a mystery

If you were to rewind the clock to the 1980s and tune your ear to the deep-sea waters off the coast of New Zealand, a peculiar sound might have caught your attention.

This sound, reminiscent of a “quack,” echoed through the South Fiji Basin’s underwater soundscape in July 1982, presenting a unique mystery for researchers investigating marine acoustics at the time.

This strange, quack-like sound quickly became a topic of widespread interest, and its continuous repetition earned it the nickname “Bio-Duck.”

Initially recorded during an experiment designed to characterize the marine audio environment of the region, the sound’s repetitive and patterned nature left researchers astonished and intrigued at the possibility that it was biological in origin.

The source of the quack still unknown

One of the pivotal contributors to this research was Ross Chapman who, at the time, was associated with the University of Victoria. He reflects about how the sound generated heated discussions among scientists who were perplexed about its source.

“The sound was so repeatable, we couldn’t believe at first that it was biological. 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 mysterious underwater communications became a major point of discussion at the 187th Meeting of the Acoustical Society of America in November, 2024, where Chapman and his team presented their findings. They have yet to identify the makers of these enigmatic sounds.

Unchartered territory of ocean noise exploration

Chapman’s journey into deciphering the mystery began in 1986 with the analysis of the data from the experiment.

“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.

The field of marine acoustics was in its fledgling stages in the ’80s, and every day was an opportunity for a new discovery.

Despite the thrill and excitement, the source of the Bio-Duck sounds remained an enigma, with some theories suggesting that the sounds could be originating from Antarctic minke whales.

Engaging in a deep-sea dialogue

Chapman, however, had a different hypothesis. He believed these sounds were something more than just random noises – they could be a conversation.

This hypothesis was supported by the pattern of the sounds recorded by an acoustic antenna, an array of hydrophones towed behind a ship.

The acoustic array’s unique design allowed the researchers to identify the direction the sounds were originating from and revealed that they came from different directions all around the ship.

“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.

This observation hinted at an organized communication pattern among the unseen marine speakers. He likened this to a conversation where one individual speaks while the others wait to respond.

A story unfolds in the deep sea

“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,” said Chapman.

While the mystery of the Bio-Duck is yet to be conclusively solved, the intriguing possibility of a deep-sea dialogue continues to fascinate us.

It offers a reminder that the underwater universe is rich with life and communication, and humbles us with the realization that there is so much more left for us to understand about the world beneath the waves.

The legacy of the Bio-Duck mystery

The quack-like sounds of the Bio-Duck are not just a relic of past research; they’ve become a cornerstone for understanding the complexity of deep-sea ecosystems.

These sounds have inspired decades of study into marine animal communication, particularly among whales and other cetaceans.

Today, advancements in acoustic technology allow scientists to revisit these historical recordings with modern tools, uncovering new layers of information that were previously inaccessible.

In recent years, the Bio-Duck has been referenced in studies seeking to map marine animal behaviors and migration patterns.

These efforts emphasize the importance of long-term data collection, proving that even recordings from the 1980s can yield fresh insights when paired with today’s computational power.

The continued analysis of sounds like the Bio-Duck serves as a reminder of the mysteries still hidden in the deep sea.

They highlight the need for sustainable marine exploration to protect these habitats and preserve the uncharted conversations of the underwater world.

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