Scientists, including Matt Fowler, who works for both Oregon State University and the National Oceanic and Atmospheric Administration, deploy a hydrophone in the North Atlantic Ocean from aboard the Icelandic Coast Guard Cutter Aegir. Hydrophones record sounds emitted by endangered whales and other species. (Photo courtesy of Dave Mellinger, OSU)
A team of researchers led by Dave Mellinger from Oregon State University’s Hatfield Marine Science Center (HMSC) detected the calls of endangered North Atlantic right whales in a former whaling ground the species had abandoned long ago.
No one saw the whales. They heard them.
Mellinger, a senior researcher with the National Oceanic and Atmospheric Administration’s Cooperative Institute for Marine Resources Studies (CIMRS) at HMSC, specializes in bioacoustics, most notably whale calls.
Funded by NOAA’s Office of Ocean Exploration and Research, the project began in 2007 by deploying five hydrophones off the Greenland coast.
Built by Haru Matsumoto at HMSC, the instruments were calibrated to record ambient sounds below 1,000 hertz - a range that encompasses the frequency of right whale calls - through a large section of the North Atlantic Ocean.
Mellinger said right whales produce a variety of sounds, and careful analysis can differentiate those sounds from other whale calls.
“We don’t know how many right whales there were in the area,” he said, noting that right whale vocalizations “aren’t individually distinctive.” “But we did hear right whales at three widely spaced sites on the same day, so the absolute minimum is three.”
While a trio doesn’t sound like much to crow about, three is a crowd for an endangered whale species with an entire population estimated at between 300 and 400. And discovering their presence in Cape Farewell Ground about 200 to 400 miles off the southeastern tip of Greenland is significant in and of itself, Mellinger noted.
Right whales were hunted to near extinction there before the adoption of protective measures. Hunting right whales became illegal in 1936, but only two have been sighted in the traditional whaling ground during the past 50 years.
And the whales’ old haunt lies in an area that could open to shipping if polar ice meltdown continues.
The researchers used recordings of North Atlantic and North Pacific right whales to identify their distinct vocalizations, including what are known as “up” calls. Between July and December 2007, they recorded 2,012 calls in the area off Greenland. The pattern of the whales’ movements led to a troubling conclusion.
“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,” said Phillip Clapham, a right whale expert with NOAA’s National Marine Mammal Laboratory, in a news release announcing the findings. “It’s vital that we know about right whales in this area to effectively avoid the ship strikes on what could be a quite fragile population.”
Right whales are somewhat slow, cumbersome creatures. Growing to as much as 55 feet long and weighing in at 70 tons, they often become victims of ship collisions when they move through heavily traveled Atlantic coastal waters while migrating northward. NOAA directed new speed limits in 2008 for commercial vessels along the Atlantic coast to help avoid collisions with the whales.
Evidence of more right whales traveling in the wrong place - a potential shipping lane - raised concern along with hope for the future of a whale species struggling to make a comeback.
Clapham joined Mellinger, Sharon Niekirk, Karolin Klinck, Holger Klinck, and Bo Dziak from CIMRS (a joint venture between OSU and NOAA), and Bryndis Brandsdottir of the University of Iceland on the project. The scientists presented their findings during a meeting of the Acoustical Society of America in Portland last week. The underwater recordings weren’t retrieved until the hydrophones were removed in July 2008. It took months to sift through the tens of thousands of various whale calls, using sophisticated acoustical detection software to separate the right whale calls from others.
This marks the third time Mellinger’s team has used hydrophones to locate endangered right whales.
In 2006, Mellinger and his colleagues described how they used hydrophones to identify right whales in the Gulf of Alaska, where only one confirmed sighting has occurred in 26 years. And in 2007, they identified the seasonal occurrence of right whales off Nova Scotia.
HMSC scientists first began hearing whale sounds several years ago while using the Sound Surveillance System (SOSUS) used by the Navy during the Cold War to monitor submarine activity in the northern Pacific Ocean. When the Cold War ebbed, civilian researchers performing environmental studies were given access. OSU researcher Christopher Fox first received permission to use the hydrophones at his HMSC lab to listen for undersea earthquakes - a program Bob Dziak now directs. While listening for earthquakes, researchers began picking up other sounds. They included ships, marine landslides - and whales.
Terry Dillman is the assistant editor of the News-Times. Contact him at (541) 265-8571, ext 225, or firstname.lastname@example.org.
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