Pitch of blue whale songs 'declining around the world'

Washington, December 10 (ANI): Researchers have found that the sound level of songs blue whales sing across the vast expanses of the ocean to attract potential mates has been declining for the past few decades.

Scientist at Scripps Institution of Oceanography at UC San Diego and his colleagues have mentioned it could actually be signaling an increase in the population of the endangered marine mammal.

Mark McDonald of WhaleAcoustics in Bellvue, Colo., along with John Hildebrand of Scripps Oceanography and Sarah Mesnick of NOAA Fisheries Southwest Fisheries Science Center, studied blue whale song data from around the world and discovered a downward curve in the pitch, or frequency, of the songs.

Hildebrand, a professor of oceanography in the Marine Physical Laboratory at Scripps, said: "The basic style of singing is the same, the tones are there, but the animal is shifting the frequency down over time.

"The more recent it is, the lower the frequency the animal is singing in, and we have found that in every song we have data for."

He further explained: "It may be that when (blue whale) densities go up, it's not so far to get to the closest female, whereas back when they were depleted it may have been that the closest female was a long way away.

"When they make these songs they need to use most of the air in their lungs. It's like an opera singer that sees how long he can hold a note.

"The (male) songs are made to impress the females and/or other males, so I think that's how the boy blue whales are impressing the girls, or are showing off to other boys: by making a loud and long song."

The study was published in the most recent issue of the journal Endangered Species Research. (ANI)