July 29, 2009

Nightingale Of The Ocean In Disko Bay

It wasn't that many years ago that the bowhead whale was written off as extinct in the waters around Greenland and especially in Disko Bay in northwest Greenland where University of Copenhagen has its Arctic Field Station.

But now the situation has changed and adult bowhead whales, which can grow up to 18 meters long and weigh 100 tons, have returned to the bay. Probably because global warming has opened up the Northwest Passage, making it ice free at certain times of the year for the first time in 125,000 years. This gives bowhead whales from the northern Pacific a chance to reach Disko Bay and mate with the small local population.

Hydrophones have revealed that the whales have developed very sophisticated songs that are used to attract a mate and thereby ensure the species' survival.

"Whale song is not a new phenomenon. But the special thing about the bowhead whale's song is that they sometimes sing with 'more than one voice'. They produce two different songs or sounds, which are then mixed together. This has not been seen in other baleen whales. It turns out that bowhead whales change their songs from year to year and never repeat songs from previous years. I.e. the whales have a new repertoire each year "“ presumably as part of the eternal struggle to obtain a mate," said Outi Maria Tervo, PhD student and current scientific leader and the university's field station in the town of Qeqertarsuaq (Godhavn) on Disko Island.

Her studies of the love songs of bowhead whales have just been chosen to be presented at large international conference on marine mammals later this year in Canada

At the same time the A.P. Møller fund has chosen to support the project with 1.8 million Danish kroner over a three year period.

"The bowhead whale is in the same weight class as fin whales and blue whales but they produce much more complicated songs, at higher frequencies, between 100 and 2000 hertz "“ cycles per second. At the same time the question arises whether the changes in their song repertoire are due to bowhead whales being so sophisticated that they change their songs from year to year in order to constantly attract and mate with new partners and thereby spread their genes. The bowhead whale is the only species of 'singing' whale where the gender of the singers has not yet been established," says Outi Maria Tervo who now has a serious opportunity to study bowhead whales via different types of hydrophones, thanks to donations from amongst others the A.P. Møller fund.


Image 1: Bowhead whale. Photo by John Jacobsen, University of Copenhagen

Image 2: Bowhead whale, Photo by John Jacobsen, University of Copenhagen

Image 3: Bowhead whale. Photo by Sven Betak., University of Copenhagen


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