Once upon a time in the ocean, North Pacific Right Whales thrived.
Their unique calls could be heard across the seas from Asia to North America. Intense whaling activities in the nineteenth and twentieth centuries changed all that, decimating their population. Mid-twentieth century recovery efforts—backed by international whale-protection laws—were hampered by illegal Russian whaling in the 1960s and ’70s.
Today, only several hundred North Pacific Right Whales remain, divided into two groups: one in the Sea of Okhotsk off Russia and a second in the eastern Bering Sea off Alaska. For years scientists have been seeking any sign of the Bering Sea group because it is considered one of the most critically endangered cetacean populations in the world with only about 30 animals remaining.
Now, Scripps Institution of Oceanography at UC San Diego researchers have reported some good news for the precarious population with a glimmer of hope that its numbers may be rebounding. A team led by Scripps researcher Ana Širović recorded the first evidence of these animals off the continental United States in decades.
Širović and her colleagues analyzed marine mammal sounds recorded in 2013 with four High-frequency Acoustic Recording Packages (HARPs), underwater microphones developed at Scripps that capture the calls and clicks emitted by various species. North Pacific Right Whales are known to produce distinctive low-frequency sounds—acoustically classified as up-calls, down-calls, gunshots, screams, and moans—that can travel across vast distances in the ocean.
To their surprise, the team discovered two Right Whale calls in HARP data recorded at Quinalt Canyon off Washington State, the first off the continental U.S. in more than 20 years, and separately at Quinn Seamount in the Gulf of Alaska.
“We had been looking for Right Whales for some time, knowing that the chances of hearing them were pretty small,” said Širović. “So it was very exciting and I was quite surprised when we heard their calls. It was a good day.”
“Our ability to detect rare species, such as the North Pacific Right Whale, has been dramatically improved by the development of new technology for listening underwater,” said Scripps Oceanography Professor John Hildebrand, a co-author of the study, published in Marine Mammal Science.
In 2013, two Right Whales were visually identified off British Columbia, Canada, marking the first such sightings that were made in the area in more than 60 years. Širović said there is no way of definitively knowing whether the animals seen were the same as the ones that were heard.
Nevertheless, the recent acoustic recordings and visual sightings may be good signs for the population of this rare animal and these instances “may offer a sliver of hope for its eventual recovery,” the researchers said in the report.
“Given the rarity of this species, and very few visual or acoustic sightings that have occurred outside the Bering Sea, our detections are an important indicator that this population is using a larger oceanic area of the North Pacific,” said Širović. “I think we are all doing this kind of work hoping to find good things to report. This was one of those good news moments. It was a happy finding.”
Other coauthors of the paper include Scripps researchers Sarah Johnson, Lauren Roche, Leah Varga, and Sean Wiggins. Data collection and analysis were funded by the U.S. Navy’s Pacific Fleet.
“The Navy is pleased to have funded this research leading to new scientific information on North Pacific Right Whales. The Navy continues to fund strong multi-disciplinary marine mammal research and applied monitoring programs performed by such world-class experts as Scripps Institution of Oceanography,” said Chip Johnson, program manager of the U.S. Pacific Fleet Environmental Readiness Division.
-- Mario C. Aguilera
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- A Scientist's Life: Ana Širović
- Listen to the Right Whale call recorded off Washington (wav)