Date: November 28, 2018
Source: American Geophysical Union
Blue
whales around the world are singing a little flat, and scientists may now have
more clues as to the reason why.
A new
study finds there's a seasonal variation in the whales' pitch correlated with
breaking sea ice in the southern Indian Ocean. The new research also extends
the mysterious long-term falling pitch to related baleen whales and rules out
noise pollution as the cause of the global long-term trend, according to the
study's authors.
Blue and
fin whales are among the loudest animals in the oceans as well as the largest.
Only males sing, humming about as loud as large ships. The whales' loud songs
can travel more than 1,000 kilometers (600 miles) underwater, allowing the
whales to communicate across vast oceans.
Blue
whales have been dropping pitch incrementally over several decades, but the
cause has remained a mystery. Now, the new study in AGU's Journal of
Geophysical Research: Oceans finds the same mysterious long-term trend of
falling pitch in fin whales and Madagascan pygmy blue whales. Pitch, or the
perception of how high or low a note sounds, is a result of the frequency of
the sound wave, usually measured in hertz.
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