A scientist from the Vancouver Aquarium has stated that the orcas aka killer whales which reside in the waters around Alaska and British Columbia have mysteriously turned down the volume on the noise they generate. The person who heads up the cetacean research team, Dr. Lance Barrett-Lennard, has stated that the orcas have become eerily quiet as of recent. (The word cetacean refers to marine mammals such as dolphins, porpoises, and whales)

For the past two years, Dr. Barrett-Lennard has observed the orcas traveling in smaller groups when hunting for food in longer distances from the shoreline during the summer months when that behavior is typical for them during the winter. That behavior is all the more puzzling given the lack of "vocalization" that Dr. Barrett-Lennard is observing among the orcas. He stated that it's normally quite easy to track them given the noise they generate, but they have become very quiet as of late.

Also, the mortality rate among the pod females has increased sharply among this year from the 1-2 deaths his team detects annually to as many as 8 this year. The increased loss of life among the matriarch orcas may have a profound effect on their population given the role they play in holding the groups together.

“It’s unclear at this point if the loss of so many matriarchs or the increase in Bigg’s killer whales is having an impact on resident killer whale behaviour, but the changes we’ve seen over the last two years are striking and beg an explanation," says Barrett-Lennard.

[caption id="attachment_72569" align="alignleft" width="640"] Like all cetaceans, killer whales depend heavily on underwater sound for orientation, feeding, and communication. They produce three categories of sounds: clicks, whistles, and pulsed calls. Clicks are believed to be used primarily for navigation and discriminating prey and other objects in the surrounding environment, but are also commonly heard during social interactions[/caption]

ON The Web:
Chatty northern orcas turn down the volume: scientist
http://www.canada.com/vancouversun/news/westcoastnews/story.html?id=2003cc8c-66ac-4768-825c-49515c04d8e0