World’s first study tracks dwarf minke whales
Dwarf minke whales have been tagged and tracked in Australia’s Great Barrier Reef in a world-first pilot study which 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, also involving researchers from Alaska, which 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 while the animals were known to gather each winter off Lizard Island in northern Queensland, it was a mystery where they spent the summer months.
Little is known about the dwarf minkes, which are usually between five to seven metres (16 to 23 feet) long. Although there are several hundred on the Great Barrier Reef, they went unnoticed there until the 1980s.
Whales such as the humpback and southern right are known to migrate down Australia’s east coast in the warmer months to spend the summer in the cooler waters off Antarctica, but whether the smaller dwarf minkes join them is unknown.
“We have no idea where they go,” Birtles, co-leader of the James Cook University-based Minke Whale Project, told AFP.
“The question is: do they make that long migration down to the Antarctic waters or do they go out into the South Pacific somewhere? I really would just about put equal money on those.”
Because they are open ocean whales, the dwarf minkes are near impossible to study outside the small time frame they spend on the Great Barrier Reef in mid-winter when courtship behaviour is seen.
“They are an undescribed sub species 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 to think that there is an animal here, which first of all doesn’t have a proper (scientific) name, and then you don’t know where it goes for nine months of the year. It is pretty extraordinary. Especially when it weighs five or six tonnes and is six metres long.”
The four whales had matchbox-sized tags placed on their dorsal fins in mid-July by researchers working from a sonically and infra-sonically quiet ship used by the Australian Defence Department.
By August 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 kilometres (1,860 miles) in less than 30 days.
A female whale dubbed Deep Scars was not far behind, but the remaining two — while heading south — were much further 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 colour patterns, which we use to identify individual animals,” said Birtles.
The researchers are hoping to do a more extensive study next year.