MendoCoastCurrent, October 27, 2009
Editor’s Note: Over the past few weeks there have been numerous Blue Whales showing up dead on the coast of California and a cause of the recent Blue Whale washing up on the Mendocino coast has been the topic of great discussion and mystery here. Actual cause of death has been identified by propeller of a NOAA research ship. Additionally, here’s a new theory based on noise pollution and new research: Blue whales are forced to make more noise to compete with man-made noise pollution like ship sounds and sonar. More specifically: Blue whales increase their ‘singing’ to cope with noise pollution. And: Man-made noise such as ships’ engines has caused hearing loss in whales.
LOUISE GRAY, Telegraph UK, September 23, 2009
The endangered blue whale uses sonar to navigate, locate prey, avoid predators and communicate.
However in recent years the increasing use of hi-tech sonar by ships, the noise of propellers, seismic surveys, sea-floor drilling, and low-frequency radio transmissions have made oceans noisier.
New research has shown that the whales are having to ‘chatter’ more often and for longer periods to communicate the location of prey and to mate.
Zoologist Lucia Di Iorio, of the University of Zurich, analysed the song of blue whales recorded by microphones during seismic explorations in the St Lawrence estuary off Canada’s north east coast over an eleven day period in August 2004.
“We found that blue whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating,” she said.
“This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding.”
The study, published in Biology Letters, provides the first evidence that blue whales change their calling behaviour when exposed to sounds from seismic surveys.
“This study suggests careful reconsideration of the potential behavioural impacts of even low source level seismic survey sounds on large whales. This is particularly relevant when the species is at high risk of extinction as is the blue whale,” added Dr Di Iorio.