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Dwarf minkes head from Australia to unknown summer seas

Mysterious whales tracked

AFP-JIJI

Dwarf minke whales have been tagged and tracked in Australia’s Great Barrier Reef in a world-first pilot study that hopes to solve the mystery of where they spend the summer.

Scientists at James Cook University in Queensland state are taking part in the project, which also involves researchers from Alaska. It tagged four of the whales last month and is now tracking their southerly progress down the east coast of Australia.

“Although they occur all around the Southern Hemisphere, the Great Barrier Reef hosts the world’s only known predictable aggregation of these exquisitely beautiful little whales,” the university’s Alastair Birtles said.

Birtles, who has been studying the dwarf minke for 18 years, said that while the animals were known to gather each winter off Lizard Island in northern Queensland, it was unknown where they spent the summer.

Little is known about the dwarf minkes, which are usually 5 to 7 meters long. Although there are several hundred on the Great Barrier Reef, they went unnoticed until the 1980s. Whales such as the humpback and southern right are known to migrate down Australia’s east coast to spend the summer in the cooler waters off Antarctica, but whether the smaller dwarf minkes join them is unknown.

Because they are open ocean whales, the dwarf minkes are nearly impossible to study outside the time they spend on the Great Barrier Reef in midwinter, when courtship behavior is seen.

“They are an undescribed subspecies of whale. . . . Nobody knew that they existed until about 20 years ago,” Birtles said. “It’s one of the great mysteries of the Southern Ocean.”

The four whales had matchbox-size tags placed on their dorsal fins in mid-July by researchers working from a quiet ship used by the military.

By Aug. 12, the first whale to be tagged, a young male called Spot, had left the reef far behind and was speeding south along the edge of the continental shelf off Sydney, having swum almost 3,000 km in less than 30 days. A female dubbed Deep Scars was not far behind, but the remaining two — while heading south — were much farther north.

“Their tracks have transformed our understanding of the movements of these animals, which up to this point we had only documented by divers re-sighting them and taking underwater photographs of their unique color patterns, which we use to identify individual animals,” said Birtles.

The researchers are hoping to do a more extensive study next year.