Every winter, Australia’s “humpback highway” hums to life.
Thousands of humpback whales migrate from Antarctic feeding grounds to tropical breeding areas along Australia’s east and west coasts.
Dr Vanessa Pirotta, a Sydney-based whale scientist, says that peak “blubber to blubber” traffic on the highway occurs between mid-June and early July.
That is when crowds will flock to greater Sydney’s headlands and beaches, hoping to glimpse the balletic performers as they defy their immense size.
Lucky spotters can watch whales, weighing up to 40 tonnes, breach and crash back into the Pacific Ocean, flanked by bursts of sea spray.
“You don’t need a boat to see a whale,” Pirotta said. “I would encourage Sydneysiders to look out on their weekend or morning walk because we have such a fabulous coastline.
“Anywhere you can see the ocean, you have a chance of spotting a whale.”
Once hunted to near extinction, the humpback whales –Megaptera novaeangliae– have made a remarkable recovery.
Population estimates now range between 30,000 and 50,000.
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But as numbers grow,migration patterns are shifting.
“Some are hanging out here all year round, at least in those colder southern waters like Tasmania,” Pirotta said.
Global heating, shifting food sources and warming oceans are likely factors – with implications for future marine life.
No longer listed as a threatened species, humpbacks still face risks in increasingly industrialised seas.
Entanglement in commercial fishing gear, shark nets and drum lines, vessel strikes and acoustic pollution from seismic blasting are all potentially deadly hazards.
Last year, it took rescuers almost five hours to free a younghumpback whale in Sydney Harbourafter it became entangled in ropes and buoys.
“When you’re a migrating animal the size of a bus, there are a number of challenges that whales face that we as humans present,” Pirotta said.
The growing humpback population means conservation efforts “need to be bumped up”, she said.
Melting Antarctic ice is also threatening krill – a key food source for the whales, which are so important to supporting ocean health.
“Their poo drives nutrients and helps the food chain, which we rely on, especially our fisheries industry,” Pirotta said.
Pirotta works with the Gamay Rangers, who care for country around Gamay (Botany Bay). “Indigenous knowledge holders reflect the past of our First Nations scientists, our first whale scientists,” she said.
For many saltwater people of the east and west coasts, whales are sacred and hold a significant cultural and spiritual place.
Yuin man Dr Jack Pascoe, an ecologist at the University of Melbourne, said the whales –Gurawal– hold lore in the form of stories.
Pascoe helped establish theSaltwater People’s Alliance, which advocates for the preservation of whalesong lines.
He said Australian environmental laws are “flawed and not fit for purpose”. Stronger action on climate and moreIndigenous-led conservationstrategies thatrecognise species of cultural significancewere needed, he said.
Simon Miller, from the Australian Marine Conservation Society, has said the “pressing international threat” of climate change is affecting whale migration and marine ecosystems.
“Australia needs to be a leading global citizen and do our bit … keeping global warming to 1.5 degrees,” Miller said.
Like Pascoe, he has urged state and federal governments to develop stronger environmental policies.
According tothe CSIRO, sea surface temperatures in Australia have risen by 1.08C since 1900, with the greatest warming off the south-east and Tasmania.