Jun 21, 2019 by News Staff / Source
The North Pacific right whale (Eubalaena japonica) is a very large, thickset baleen whale species that is extremely rare and endangered. It ranges from Japan in the west to Alaska and the west coast of North America in the east. A team of marine biologists from NOAA Fisheries and the University of Washington has recorded singing (recording #1 and recording #2) from the rare species in the southeastern Bering Sea.
The North Pacific right whale (Eubalaena japonica). Image credit: NOAA.
“During a summer field survey in 2010, we started hearing a weird pattern of sounds. We thought it might be a right whale, but we didn’t get visual confirmation,” said Dr. Jessica Crance, a researcher at NOAA Fisheries’ Alaska Fisheries Science Center.
“So we started going back through our long-term data from moored acoustic recorders and saw these repeating patterns of gunshot calls. I thought these patterns look like song.”
“We found them again and again, over multiple years and locations, and they have remained remarkably consistent over eight years.”
Gunshot calls are part of the right whale’s known repertoire, along with upcalls, screams, and warbles. But they had never before been heard as part of a repeating pattern.
While the scientists suspected that the songs were produced by a right whale, they had only the acoustic recordings, with no visual confirmation — until two summers ago.
“We heard these same songs during a summer survey in 2017, and were able to localize the songs to male right whales,” said Dr. Crance, lead author of a paper published in the Journal of the Acoustical Society of America.
“We can now definitively say these are right whales, which is so exciting because this hasn’t been heard yet in any other right whale population.”
“Why is this population of right whales singing? Do the other populations also sing, and it just hasn’t been documented yet, or is this unique to our population?”
“Working in the very remote, harsh, and large Bering Sea, getting the answers will be very difficult. That is one of our biggest challenges — our population has fewer than 30 whales.”
According to the team, these songs are a reproductive display.
“We have direct evidence of male right whales singing, and we think this may be exclusive to males, but we have very limited data on vocalizing female right whales,” Dr. Crance said.
As to why North Pacific right whales sing, the researchers theorize that their extreme rarity gives them reason to sing.
“With only 30 animals, finding a mate must be difficult. Lone male right whales tend to gunshot more frequently than females. Perhaps the 2:1 male ratio in the North Pacific has led to our males singing to attract females. But we may never be able to test that or know for sure,” Dr. Crance said.
“Our next step will be to look at the evolution of the songs over time, and their seasonality, to determine if certain songs are produced at specific times. We also want to find out whether these songs contain individual-specific information.”
Jessica L. Crance et al. 2019. Song production by the North Pacific right whale, Eubalaena japonica. Journal of the Acoustical Society of America 145 (6): 3467; doi: 10.1121/1.5111338
Thanks to: http://www.sci-news.com