For more than five decades research scientists investigating the Antarctic and the Antarctic (Southern) Ocean–which are vital repositories of frozen records that reveal eons worth of data on oxygen and carbon levels, plant and animal life, mineral deposits, temperature and topography that help science understand current global warming and climate change–have recorded an unidentifiable sound. Submarine personnel first recorded the sound in the 1960s and, thinking the sound was like the quack of a duck, called it the “bio-duck.”
Bio-Duck Minke Whale
Prior to the announcement on 23 April 2014 in Biology Letters, no one knew what the bio-duck was. Some speculation was that the sound was submarines in the waters or an oceano-graphic phenomenon or mystery fish. Denise Risch of NOAA’s Northeast Fisheries Science Center (NEFSC) has announced that the bio-duck is the minke whale . No one knew that the minke whale inhabited the Southern Ocean waters across higher (So. hemisphere, colder) and lower (So. hemisphere, warmer) latitudes during the austral winter months, which is when the bio-duck sound is primarily heard.
Minke whale have been reported in all seas from Norway to Brazil to Japan to South Africa to Australia beginning from 800 B.C.E when they are first mentioned in a written source in Norway. The minke became the target of contemporary whale hunters after the overhunting of large whales species, like the blue and fin whales, and have been hunted by Japan, Norway, Iceland, and South Korea in recent decades. A small whale species, the minke is the smallest rorqual or “great whale.” Like other rorquals, the minke is streamlined, with a pointed head and small pointed fins. Minke come in two varieties: the Common minke of Northern waters and the Antarctic minke of Southern waters.
Wintering Antarctic Minke
Mystery surrounded the bio-duck sound because it was not known that during the migratory austral (southern hemisphere) winter season, a large population of Antarctic minke remained throughout the winter in the ice-covered Antarctic Ocean while others migrated to lower southern hemisphere latitudes to winter in warmer waters.
Minke Acoustic Tags
The breakthrough came after February 2013 when Risch’s NEFSC international research team deployed acoustic tags on two Antarctic minke whales in the locale of the Western Antarctic Peninsula in Wilhelmina Bay. The analysis, led by Risch, and comparisons to archived sounds of the year’s worth of collected acoustic data–recordings of “a series of pulses in a highly repetitive pattern”–led to the discovery that the mysterious bio-duck was the sound of the minke whale, not submarines, oceano-graphic phenomenon or mystery fish.
Minke in the Unstable Antarctic Region
Unraveling the bio-duck mystery leads to unraveling a greater mystery. Little is known of the Antarctic minke’s habits. As Risch says: “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.” Now, Antarctic minke whales can be monitored in a broader range of territories. Since the Antarctic minke is an inhabitant of the Antarctic region, it is thought by the researchers to be critical to learn more of its habits because the region is both geographically unstable , with “rapidly changing sea-ice conditions,” and politically unstable , with “contentious lethal sampling efforts and international legal actions.”
Acoustic Recordings of Bio-Duck . Credit: Denise Risch, NEFSC/NOAA.
Shelley Dawicki. ” Scientists Identify Source of Mysterious Low-Frequency Sound Heard for Decades in the Southern Ocean .” National Oceanic and Atmospheric Administration Fisheries Service and Northeast Fisheries Science Center at Woods Hole Laboratory.
Denise Risch, et al. ” Mysterious bio-duck sound attributed to the Antarctic minke whale .” Biology Letters, Royal Society Publishing. 2014.
” Minke whale .” Wikipedia.
” Minke whale .” Wikipedia.