Whales riding ‘blue highway’
Previously hidden Soviet whaling records and satellite tracking data reveals humpback whales have been following the same ‘‘blue highway’’ for more than 50 years.
‘‘These findings reveal an apparent paradox: humpback whale migrations do not change in a changing ocean,’’ University of Canterbury Associate Professor Travis Horton said.
And that might be to the detriment of the whales.
Horton is one of the authors of a new international study looking at the migratory route of humpback whales, or paikea, in the South Atlantic Ocean.
The study uses satellite tracking data from 20 whales tagged between 2003 and 2018, as well as records from a Soviet fleet with the locations of 243 humpbacks killed between 1965 and 1973.
According to the authors, the records may have been kept hidden in the potato cellar of a whaling captain until the end of the Cold War.
Horton said the satellite data showed the whales followed a narrowly defined migratory route more than 3000 kilometres south-southeast from breeding grounds off the coast of Brazil near Rio de Janeiro to feeding areas to the east of the remote South Sandwich Islands.
‘‘It’s like a blue highway,’’ he said. ‘‘It wasn’t until I went back to the Soviet whaling data and I looked at where the Soviet kills had occurred that I was like, ‘oh my goodness, they’ve been following exactly the same corridor for 50 years’.’’
That they kept following such a defined route, which was not the shortest way to good feeding grounds, showed they had some kind of in-built navigation, Horton said.
‘‘With respect to climate change, if the whales continue to keep going to the same places but those places change due to environmental or climate change, those habitats, those places that the whales are migrating to, may not be able to serve the whales’ needs anymore.’’