AFTER being hunted to near extinction and threatened with climate change, drones are giving southern right whales in the Great Australian Bight a much-needed health check.
Sponsored by WWF-Australia, researchers at Murdoch University are measuring the size of individual whales and monitoring how that changes during the calving season, with plans to track their weight each year.
Work done this year reveals how much weight mothers lost as they fattened up their calves – shrinking by as much as 43cm in two months.
WWF-Australia whale researcher Chris Johnson said southern right whales journey thousands of kilometres from the Antarctic where they feed to South Australia’s Head of Bight to give birth. They stay there for about three months to fatten their calves before returning to Antarctica.
Johnson said the whales don’t eat for four months, relying only on their fat reserves. He said one mother they watched, named Scooter, was 2.85 metres across her belly on 3 July but only 2.42 metres across two months later.
Another mother, Bella, lost 31cm in the same period, while her calf grew from 5.84 metres long to 7.67 metres.
Johnson said this dramatic loss of weight the mothers undergo makes them more susceptible to other threats.
“These include getting tangled in marine debris, disturbance from oil and gas development, and global ocean warming which could reduce their food supply in Antarctica,” he said.
“That’s why this project is so important. If the condition of the whales changes in the future it could be a sign that human activities are having an impact.
“Nurturing a calf is already tough enough for the mothers without humans adding to the pressure.”
Murdoch University researcher Fredrik Christiansen said because of the weight loss the mothers undergo, they could only give birth every three or four years.
“When they arrive they have significant fat reserves, they are wide all along their body. When they leave they look like giant tadpoles. They have a head which is still big and robust, but the rest of the body is skinny and you can even see the spinal cord showing up,” Christiansen said.
“There is still so much unknown about whales. My long-term goal is to understand how human impacts, both lethal and sub-lethal, affect behaviour, health and ultimately the recovery of whale populations,” he said.
WWF Australia is launching a campaign, Safe Seas for Whales, asking for donations to fund the research.
Story Source: : WWF Australia / The Guardian