Scientists have been stumped over a "bio-duck" sound in the Southern Ocean near Antarctica for more than 50 years, but they have finally figured out what is causing it.

According to LiveScience, the research team published their work Tuesday in the journal Biology Letters. First heard when submarine crews detected the noise in 1960s, the researchers determined Antarctic minke whales make the noise.

For their study, Denise Risch, a marine biologist at NOAA Northeast Fisheries Science Center in Woods Hole, Mass., and her team analyzed years' worth of audio files. She said scientists originally thought the sound was manmade, from a submarine, because of its low pitch and repetitiveness.

The team tagged two whales off the Western Antarctic coast for the purpose of tracking their feeding habits, but the suction cup tags also had microphones. The noises were often heard three seconds apart and sometimes simultaneously.

Risch wrote in the study the bio-duck sound "can now be attributed unequivocally to the Antarctic minke whale."

Not much is known about the Antarctic minke whale, or Balaenoptera bonaerensis.

"These results have important implications for our understanding of this species," Risch said in a press release. "We don't know very much about this species, but now, using passive acoustic monitoring, we have an opportunity to change that, especially in remote areas of the Antarctic and Southern Ocean."

Learning more about these animals will allow conservationists to survey their movements in the winter since the colder months make visual tracking difficult.

"The fantastic thing about acoustics is you can go back in time," Risch told LiveScience.

Japan was recently barred from whaling and research like this provides an alternative to the controversial practice. All researchers would need to do is hand microphones on buoys in the summer and analyze the data for the winter.

Risch said her team's study "shows killing is not necessary."