They survived commercial whaling, but a large-scale Antarctic expedition has provided more insights into how climate change could re-shape future generations of whales.
Olaf Meynecke, who heads Griffith University's whale and climate research program, was one of 100 scientists and documenters on board a two-week expedition to the western peninsula of Antarctica this month.
Dr Meynecke has documented how humpbacks adapt their feeding behaviour for areas with an abundant food source.
"How much food was there, defined what kind of feeding behaviour they were showing," he said.
"In areas with a lot of krill, they were doing bubble net feeding and socialised feeding.
"They're working together in groups of four or five and just constantly doing these bubble rings which is herding the krill to the centre and the others were getting the krill — doing this again and again with no stop."
While whales use the relatively high density of krill in Antarctic waters to feed up before their northern migration, Dr Meynecke says melting sea ice is threatening that food supply.
Lowest measurements on record
Led by renowned marine ecologist Sylvia Earle, the expedition was designed to be "a gathering of good minds, making commitments for action".
"If we wait much longer, opportunities that are now possible, will be lost," Dr Earle said in 2022.
"It's going to get harder and harder as time goes by to take actions that are in our grasp right now."
This week the Intergovernmental Panel on Climate Change (IPCC) published its final "synthesis report" warning that "deep, rapid and sustained" emission cuts are needed to limit warming to 1.5 degrees Celsius this decade.
Dr Meynecke said "signs of climate change" were evident through the expedition.
"What matters for the whales is how fast the ice is melting," he said.
"This year, it's been the lowest ice amount for Antarctica since 1970, since the measurements with satellites were done."
A 2019 study published by Global Change Biology, noted rising sea water temperatures were likely to reduce krill numbers, with the density of the crustaceans in the Scotia Sea, south-east of Argentina, declining by 30 per cent since the 1980s.
The whale study, led by Vivitskaia Tulloch from the University of Queensland, stated that "despite initial recovery from historical whaling", models have predicted "concerning declines under climate change, even local extinctions by 2100".
"[As a] consequence of reduced prey (copepods and krill) from warming and increasing inter-specific competition between whale species," it said.
Fewer prey, longer distances
The study "highlights the need for ongoing protection to help depleted whale population recovery, as well as local management to ensure the krill prey base remains viable".
"But this may have limited success without immediate action to reduce emissions," it said.
Krill eat algae under sea ice, especially during winter months.
But the study found that as ice levels melt, whales may need to travel further to find new sources of food, leading to more intense competition between species.
It notes that baleen whales, which includes humpbacks, are "likely to be particularly sensitive to future climate change".
Dr Meynecke says in areas with fewer krill, whales feed more independently.
"They were usually just individuals and they were feeding in the mid-waters, maybe to 50 metres, 100m depth," he said.
Dr Meynecke says the "very remote and hostile" Antarctic waters are vital for the future sustainability of whale populations.
"I look at them here on the east coast of Australia and I see relatively skinny whales compared to what I've seen down there because they've fed up on krill," he said.
"It's such a different environment.
"Imagine these animals experience both — the tropics, the Great Barrier Reef but then also swimming through ice and ice-cold waters in the same year."
