Washington: Researchers have found that not all Southern Hemisphere humpback whales migrate towards the equator at the end of the Antarctic summer.
Biologists and physicists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, found that part of the population remains in Antarctic waters throughout the entire winter.
This surprising discovery based on underwater recordings from the Antarctic acoustic observatory PALAOA. It is located near the research base Neumayer Station III on the ice shelf and regularly records underwater sounds of humpback whales even in the austral winter months.
Ilse Van Opzeeland, a marine biologist and expert on large whales at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) one day switched on the live stream of PALAOA, the underwater acoustic observatory, and the loudspeakers suddenly resounded with the calls of humpback whales - and this at a time during which the marine mammals should long have been swimming 7,000 kilometres further away in the warmer waters off Africa.
Driven by the question whether the winter-excursion of the humpback whales in the eastern Weddell Sea was a unique event, Ilse Van Opzeeland developed a procedure for the automatic detection of humpback whale calls and analysed all PALAOA recordings from 2008 and 2009 for acoustic signs of life from these animals.
She said that along with variable, high-frequency calls from the whales, our recordings also contain stereotyped calls that sound a bit like a moan.
The research has been published in scientific journal PLOS ONE.