Thanks to a system of underwater hydrophones, scientists have been able to document the presence of North Atlantic Right whales in an area where they were believed to have gone extinct.

The North Atlantic Right whale (Eubalaena glacialis), where even the name is a reference to it being the “right” whale to hunt, was heavily targeted by whalers during the 19^th and 20^th century and the entire species was on the brink of extinction when the moratorium on whaling was implemented in the 1960s.

Being an important whaling area throughout the 19^th century, Cape Farewell Ground off the southern tip of Greenland was believed to have no surviving population of Right whales, but when scientists from Oregon State University (OSU) and the National Oceanic and Atmospheric Administration (NOAA) begun investigating the area using hydrophones, they recorded a total of 2,012 Right whale “calls” from July through December 2007.

“We don’t know how many right whales there were in the area,” says David Mellinger, assistant professor at OSU’s Hatfield Marine Science Center in Newport and chief scientist of the project. “They aren’t individually distinctive in their vocalizations. But we did hear right whales at three widely space sites on the same day, so the absolute minimum is three. Even that number is significant because the entire population is estimated to be only 300 to 400 whales.”

During the last 50 years no more than two Right whales have been sighted at Cape Farewell Ground, so even a figure as low as three during the same day is good news.

The project has been using five hydrophones engineered by Haru Matsumoto at OSU, configured to continuously record ambient sounds below 1,000 Hz over a large region of the North Atlantic. These underwater hydrophones are sensitive enough to record sounds from hundreds of miles away. The scientists used previous recordings of Atlantic and North Pacific Right whales to identify the species’ distinct sounds, including a type of vocalization known as “up” calls.

“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,” says Mellinger.

Results of the 2007 study were presented this week at a meeting of the Acoustical Society of America in Portland, Oregon.

In addition to Mellinger and Clapham, scientists involved in the project include Sharon Nieukirk, Karolin Klinck, Holger Klinck and Bob Dziak of the Cooperative Institute for Marine Resources Studies – a joint venture between OSU and NOAA; Phillip Clapham, a right whale expert with NOAA’s National Marine Mammal Laboratory, and Bryndís Brandsdóttir of the University of Iceland.