Surprise baby whale sightings along a busy 'humpback highway' prompt new worries

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Whale researchers combined modern-day sightings with 19^th century records and are revealing new information about when and where humpback whales give birth along a busy “humpback highway” off Australia.

Humpback calves are being born not just in a calving zone at the end of the migration route, but along the way and even farther south than previously understood, according to a study led by researchers at the University of New South Wales.

That pattern raises new issues, including the need to increase awareness to protect newborn whales throughout their winter journeys, the authors wrote in the study published May 21 in the scientific journal Frontiers in Marine Science.

“Hundreds of humpback calves were born well outside the established breeding grounds,” said Tracey Rogers of the University of New South Wales, a senior author. “Giving birth along the ‘humpback highway’ means these vulnerable calves, who are not yet strong swimmers, are required to swim long distances much earlier in life than if they were born in the breeding grounds.”

Newborn humpbacks aren’t as strong as adult whales, and “mums with newborns swim much more slowly,” Rogers said. “Newborns are like Great Dane puppies. They have those long, enormous fins that they need to grow into, and they’re not very strong swimmers. So they rest a lot of the time on their mum’s back.”

Once near extinction, humpback whales have rebounded thanks to conservation programs. Today the population is estimated at roughly 50,000.

Sightings for the study were collected across an area extending from Queensland down to Tasmania and across to New Zealand’s South Island.

“Historically, we believed that humpback whales migrating north from the nutrient-rich Southern Ocean were travelling to warmer, tropical waters such as the Great Barrier Reef to calve,” says lead author Jane McPhee-Frew, a PhD candidate at the University of New South Wales Sydney and whale watching skipper.

“The pattern we’re seeing is mother whales with calves travelling through some of the busiest shipping lanes and urbanised regions," said McPhee-Frew. Her first calf sighting in Newcastle in 2023, home of the largest coal export port in the world, was within a busy shipping lane.

“This means these vulnerable animals are exposed to risks like boat strikes, entanglements, pollution – and just general public unawareness,” she said.

Questions remain about the whales' migration, including how the humpback mothers use different marine environments along their migration route and why they continue to travel north after giving birth, even though there's really no food for them in the tropics.

Dinah Voyles Pulver, a national correspondent for Paste BN, covers climate change, wildlife and the environment. Reach her at dpulver@usatoday.com or @dinahvp on Bluesky or X or dinahvp.77 on Signal.