May 21, 2009
Scientists Discover New Population Of Rare Whales
With the help of a device called a hydrophone, a group of researchers has recorded the voices of endangered North Atlantic right whales in a region where they were thought to be extinct.
The team of scientists from Oregon State University and the National Oceanic and Atmospheric Administration explained that the discovery is particularly significant because the whales are in an area that may soon be open to oceanic shipping vessels if the polar ice cap continues to melt.The group presented their findings this week at a meeting of the Acoustical Society of America in Portland, Ore.
Between July and December of 2007, the team of researchers was able to record more than 2,000 right whale vocalizations in an area off the southern coast of Greenland. They say they are still unsure as to the exact number whales actually inhabit the region, which used to be prime whaling waters some hundred years ago.
"The technology has enabled us to identify an important unstudied habitat for endangered right whales and raises the possibility that"”contrary to general belief"”a remnant of a central or eastern Atlantic stock of right whales still exists and might be viable," explained David Mellinger, the project leader and assistant professor at OSU's Hatfield Marine Science Center in Newport.
"We don't know how many right whales there were in the area. They aren't individually distinctive in their vocalizations, but we did hear right whales at three widely spaced sites on the same day, so the absolute minimum is three," said Mellinger.
"Even that number is significant because the entire population is estimated to be only 300-400 whales," he added.
In the previous half century only two right whales had been sighted in these waters and many assumed that heavy hunting in the early 19th century had driven them to extinction.
The group was able to detect the whales using five hydrophones set up in various locations off the southern tip of Greenland. The devices were programmed to continuously record ambient sounds below 1,000 Hz, the range within which right whale vocalizations fall.
Mellinger explained that right whales are capable of producing a surprising variety of sounds, which scientists are able to distinguish from the vocalizations of other species of whales.
The pattern of calls recorded by the team indicates that the whales were migrating from the southeastern corner of the region towards the northeastern corner in late July and returning in September"”a migration route that will put them right in the middle of proposed shipping paths.
"Newly available shipping lanes through the Northwest Passage would greatly shorten the trip between Europe and East Asia, but would likely cross the migratory route of any right whales that occupy the region," explained Phillip Clapham, an expert on the rare whales who also took part in the study.
"It's vital that we know about right whales in this area in order to effectively avoid ship strikes on what could be a quite fragile population."
Mellinger and his colleagues have had a good bit of practice using hydrophones to find right whales in recent years. In January 2004, they published similar findings after locating a number of the endangered mammals in the Gulf of Alaska and again in Nova Scotia in 2007.
The team's first experience utilizing hydrophones to record whale vocalizations came after they received permission to use the U.S. Navy's Sound Surveillance System (SOSUS) which had been used during the Cold War to monitor submarine activity in the northern Pacific.
Matsumoto, an engineer at OSU's Hatfield Marine Science Center, was later able to develop a separate set of hydrophones capable of being deployed independently. The underwater acoustic technology has since become an indispensable asset to marine ecologists and marine geologists alike.
On the Net: