Antarctic blue whales belong to three populations

Antarctic blue whale numbers were drastically reduced due to whaling in the past, with only an estimated 360 left in the 1970s.

Sydney: Antarctic blue whales, the largest creatures on the planet, likely belong to three populations that feed alongside each other but breed in separate oceans, according to Australian-led research published yesterday.

Using the largest data set ever obtained from the critically endangered subspecies, the study in the Scientific Reports journal seeks to shed light on blue whale populations to aid their conservation.

“We found genetic evidence that there are three groups of Antarctic blue whales that likely represent three populations,” the study’s lead author Catherine Attard, a biological sciences lecturer at South Australia’s Flinders University, told AFP.

“We suspect that each population migrates north to breed in a different ocean basin.” Relatively little is known about the Antarctic blue whale, even though they are the biggest animal in the world and can grow to more than 30m in length.

Attard said the animals fed on krill in Antarctica in the southern hemisphere summer, but exactly where they headed to next was a mystery.

She said they likely migrated north to the South Pacific, South Atlantic and Indian oceans to breed as the southern hemisphere winter approached.

The idea that the whales split up to breed has been around since the 1960s, and Attard said it was possible that calves learned their migratory routes from their mothers.

But she said satellite tracking now needed to be done to confirm the majestic animals’ migratory routes and breeding grounds. Knowing the number and distribution of populations would help prevent biodiversity loss, the study noted.

Antarctic blue whale numbers were drastically reduced due to whaling in the past, with only an estimated 360 left in the world in the 1970s when they were last hunted.

Attard said current estimates were that there were “several thousand” of the huge creatures, but they remained surrounded by mystery given the difficulty of studying them in the harsh and remote Antarctica and their wide-roaming nature.

“It’s quite amazing that they are the biggest animal and we don’t know much about them,” she said.

The Antarctic blue whale, which is known for its deep resonating song, can weigh up to 180 tonnes and is said to have a heart as big as a small car.

The latest study used genetic samples obtained between 1990 and 2009, as part of research approved by the International Whaling Commission.

( Source : AFP )
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