Tracking Right Whales
INTRO: Whale hunters once called them the right whale, because they were large, slow-moving and floated after death. So "right" were these whales that hunters succeeded in driving the species to near extinction by early in the last century. Today, right whales in waters of both the Atlantic and Pacific Oceans are among the world's most critically endangered species. In the Bering Sea, off Alaska, scientists say less than three dozen northern Pacific right whales cling to existence. As Doug Schneider reports in this week's Arctic Science Journeys Radio, researchers have begun listening in on their undersea calls, in the hope they might help Alaska's right whales recover.
STORY: This mournful call is of a northern right whale recorded just last summer in Alaska's Bering Sea. With less than 50 individuals left in the wild, Alaska's right whales are among the world's most endangered species. Lisa Munger is a graduate student at Scripps Institution of Oceanography in California. She says the call is of a right whale looking for others of its own kind.
MUNGER: "The predominant call that we hear in our data is an upsweep, and that's been assumed to be a contact call, meaning they use it to find each other in the ocean. There have been playback experiments where if they play that call, a right whale will swim up to the speaker to see what's going on."
Right whales are so rarely seen that Munger and her colleagues two years ago began recording their vocalizations as a way to track movement patterns as they foraged for tiny crustaceans called copepods throughout the long Alaska summer. Technicians with the National Marine Mammal Lab and Whale Acoustics, Inc., placed four sound recorders on the seafloor in waters off Alaska where right whales are known to frequent. The array recorded hundreds of calls. Periodically, Munger also listened in from aboard a research ship.
MUNGER: "We also found out that they have a diurnal calling pattern. We've seen them mostly calling at night when we were on the ship. And then in my sound array data they call at dawn and dusk. They're kind of quiet during the day."
Each summer, huge plankton blooms attract massive schools of copepods. Right whales, which can grow to more than 50 feet and weigh up to 60 tons, arrive to devour the copepods. They do this by straining them, along with thousands of gallons of seawater, through large baleen plates in their mouths. Scientists once believed the whales left the region soon after the summer's last plankton bloom. But through the recordings, Munger learned that Alaska's right whales stayed longer in the Bering Sea than previously thought.
MUNGER: "It seems that they're up in the Bering Sea a lot later than everyone had thought previously. I have seen calls in my data into early November. People had thought they got out of there in August and September. So it's interesting that they are there a couple of months longer. That could be related to a second plankton bloom in the Bering Sea, so they could be hanging out and feeding up there."
Besides using the calls as a tool to track right whale movements, Munger hopes to learn just what the sounds actually mean. To do this, she's tried to watch the whales' behavior when they vocalize. But since the whales call mostly at night, that effort hasn't been very successful. And Munger says that after November, her sound recorders didn't pick up any more right whale calls. That could be because the whales left or simply stopped calling.
MUNGER: "Scientifically, all we can say is that we heard no more calls. But the assumption is that they did indeed leave the area and went to some other place we don't know about."
Finding out just where Alaska's rarest whales spend the winter is high on Lisa Munger's to-do list. But first she hopes to combine her data about right whale movements with what's known of the region's ocean currents, plankton blooms and other information, to construct a model of what right whales need to survive.
If you'd like to learn more about Lisa Munger's study of right whales, come to our website at www.asjnews.org. This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. I'm Doug Schneider.
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Thanks to the following individual for help preparing this script:
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