Scientists have spotted several Antarctic blue whales in the Southern Ocean

A rare Antarctic blue whale seems to have an affinity for the Niwa research vessel Tangaroa, tracking the ship nearly 600km across the icy Southern Ocean.



Scientists on a six-week research journey first spotted the whale, which they've nicknamed Penfold, at the Balleny Islands on February 6.



They've spotted the same whale another four times time since.

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The latest sighting of Penfold was in an area about 600km from the islands.

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"It's been moving with us - or we've been moving with it," Paula Olson of the Australian Antarctic Division said.

Scientists on board the Tangaroa have encountered about 30 blue whales within an area of about 400 square kilometres.

There are thought to be only a few hundred of the enormous marine mammals left, although it's hoped the research will help to improve understanding about their number.

Paula Olsen SURFACED: Scientists have spotted several Antarctic blue whales in the Southern Ocean

The scientists are using 'sonobuoys' to hear the calls of the whales.

The 'sonobuoys', which are ordinarily used by the military to find submarines, have underwater sensors to detect sounds and a magnetic compass for determining where the sounds are coming from.

"We were able to track Antarctic blue whales hundreds of miles away," Susie Calderan, an Australian Antarctic Division scientist on board, said.

"Gradually, by deploying sonobuoys and plotting their bearings, [we got] close enough to the animals to see their large powerful blows on the horizon, which finally led us to them."

The researchers have got close enough to take small biopsy samples from some of the whales.

The whales were "massive, very beautiful and surprisingly swift and agile for their size," Calderan said.

"It's a great privilege and joy to be able to observe these whales in an environment as exceptional as the Antarctic."

The scientists are also learning more about what the whales eat, by chasing the big balls of krill that they swallow.

Echo-sounder surveys have shown dense balls of Antarctic krill at depths of less than 100 metres in the areas where several blue whales had been found.