Scientists discover source of Southern Ocean’s mystery ‘quack’, solving 50 year mystery

SCIENTISTS have finally identified the source of strange “duck-like quacks” first heard in the Southern Ocean off Australia 50 years ago.

A MYSTERIOUS duck-like sound recorded in the ocean around Antarctica has puzzled scientists for more than five decades.

But this week, the source of the sound, nicknamed the “bio-duck”, was finally found.

Submarine crews first heard the quack, which consists of a series of repetitive, low-pitched pulsing sounds, in the 1960s.

“In the beginning, no one really knew what it was,” marine biologist Denise Risch told Live Science.

Because the sound was so repetitive, scientists first thought it might be man-made, possibly coming from submarines.

In later years, others suggested a fish might be the source -- but it seemed too loud, Risch told the website.

Turns out those quacks were being made by minke whales.

If it quacks like a duck ... it might be a Minke whale.

The US-based researcher and her team collected years worth of audio recordings, noting they came in sets spaced about 3.1 seconds apart.

The noises also occurred seasonally and have been heard simultaneously in the Eastern Weddell Sea off Antarctica and Western Australia, Risch told Live Science.

The breakthrough came after Risch’s colleagues attached suction-cup tags to a pair of Antarctic minke whales off WA in February last year with the intention of monitoring their feeding behaviour and movements.

Minke whales in the Southern Ocean around Antarctica have been quacking at scientists in vain for fifty years ... until now.

The tags also contained underwater microphones. When Risch listened to the recordings, she found they contained the duck sounds, as well as downward-sweeping sounds previously linked to the whales.

The sounds “can now be attributed unequivocally to the Antarctic minke whale,” Risch and her team wrote in a study published in the latest edition of the journal Biology Letters.

But while they have cracked the source of the quack, scientists still have no idea what the sound means in whale-speak, or whether they are made by male or female whales or both.