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Blue Whales Split into Three Breeding Groups

Flinders University scientists have uncovered crucial DNA evidence about the number and distribution of populations of the world’s largest animal, the critically endangered Antarctic blue whale.

Using the largest genetic dataset to date, the researchers have discovered three genetically different groups that represent different populations of the animal. This means that when Antarctic blue whales breed, they may split into three different oceans that equate to the three populations.

“What really surprised us was that these populations co-occupy areas throughout the Antarctic, rather than occupying discrete areas like their humpback whale cousins,” says Dr Catherine Attard. “The blue whale populations likely move around the Antarctic to locate their sole food source, krill. Blue whales require high densities of krill to support their massive energy requirements.”

Antarctic blue whales feed in the Antarctic during the summer and migrate towards the Equator to breed in the winter. This means that when Antarctic blue whales breed, they may split into three different oceans that equate to the three populations.

“We have provided a piece of the population puzzle, but still have far to go before we can properly monitor and conserve these populations. We need to determine their breeding ground locations and then confirm their population structure,” says A/Prof Luciana Möller.

The findings have been published in Scientific Reports (www.tinyurl.com/zhcfqrq).

International whale surveys have been conducted in the Antarctic since 1978. Non-lethal biopsy samples have been collected from blue whales during these surveys.

“By comparing similarities and differences in the DNA of blue whales, we can tell which individuals are part of the same population and estimate the number of populations,” says Prof Luciano Beheregaray.

The researchers say this would ideally be performed by continuing the international vessel surveys in the Antarctic and conducting satellite tagging of Antarctic blue whales to determine their migratory destinations.