Eastern Australian humpback whales now exceed pre-whaling population numbers

Story: 2025 C.E.  |  Last updated: October 22, 2025

A species once reduced to 150 animals along Australia’s eastern coast has now surpassed the population it held before industrial whaling began. Marine scientists estimate that more than 50,000 eastern Australian humpback whales completed their annual migration in 2024 — roughly 20,000 more individuals than the estimated pre-whaling population of the early 1900s. Researchers are calling the recovery “a near miracle.”

At a glance

• Humpback whale recovery: The eastern Australian population has grown from around 150 survivors in the early 1960s to an estimated 50,000–60,000 individuals in 2024, surpassing pre-whaling numbers.
• Citizen science network: Nearly 700 researchers, whale-watch operators, and citizen scientists contributed photographs and sightings to the HappyWhale tracking catalogue, producing a 40-year dataset of more than 15,000 individually identified whales.
• Whaling ban: The International Whaling Commission banned humpback whaling in the Southern Hemisphere in 1963 C.E., triggering a slow-then-accelerating recovery that scientists say may now be approaching its natural ceiling.

From 150 animals to 50,000

The scale of the collapse that preceded this recovery is worth stating plainly. Before large-scale industrial whaling, eastern Australian humpbacks were, by historical accounts, in “spectacular abundance.” Early 19th-century records from Hobart describe sailors navigating carefully through crowds of whales in the Derwent River, and waterfront residents complaining about the noise of whale song.

That changed fast. As blue whales and southern right whales were hunted toward local extinction, whalers turned to humpbacks. By the early 1960s C.E., the eastern Australian population — once estimated at around 30,000 individuals — had been reduced to roughly 150 survivors.

The IWC’s 1963 C.E. ban on Southern Hemisphere humpback whaling marked the turning point. In the three decades that followed, numbers climbed slowly back to around 1,000 individuals. Through the 1990s and 2000s the pace quickened. A formal estimate placed the population at about 25,000 in 2015 C.E. The new preliminary report, submitted to Australia’s federal Department of Climate Change, Energy, the Environment and Water, now puts the 2024 C.E. figure at more than 50,000 — and possibly as high as 60,000.

Wally Franklin, co-founder of the Oceania Project and one of the report’s co-authors, has studied this population for more than 30 years. “The recovery of the group,” he said, “is a near miracle.”

How scientists counted them

Individual humpbacks can be identified by the unique patterning and notching on the underside of their tail flukes — effectively a fingerprint. The new estimate drew on the HappyWhale catalogue, which aggregates whale photographs submitted by scientists, commercial whale-watch operators, and members of the public.

By 2024 C.E., that collaborative effort had produced a 40-year dataset covering more than 15,000 individually identified whales with multiple recorded sightings per animal. Statisticians fed the full dataset into population models to arrive at the new estimate.

The report is preliminary and has not yet been peer-reviewed — a limitation the authors acknowledge. But it aligns closely with earlier predictions that the eastern humpback population would peak near 50,000 individuals sometime in the 2020s C.E.

Why these whales recovered when others have not

Not every whale population has followed the same trajectory. Southern right whale numbers have plateaued well below pre-whaling levels. Some other humpback groups, including those that give birth in the South Pacific, are recovering more slowly than the eastern Australian population. Scientists don’t fully understand why.

Franklin suggests Australia’s long coastline may help. “Long coastlines provide numerous habitats that are highly suitable for mums to spend quality time with the calves in the early years of their life.” Less competition for food may also play a role.

Adelaide Dedden, a marine scientist at the University of New South Wales who was not involved in the new report, points to humpback biology. Humpbacks can breed every two to three years, while southern right whales typically calve only once every four years. Humpbacks also appear more adaptable about where they give birth: research involving Dedden found that eastern humpbacks will calve in cold temperate waters, not only in tropical zones. Southern right whales, by contrast, rely on sheltered coastal bays — environments where human disturbance is harder to minimize.

What 50,000 whales mean for the ocean

The return of humpbacks in large numbers is more than a conservation milestone. It is an ecological event.

Whales play a significant role in ocean nutrient cycling. When they feed at depth and surface to defecate, they return iron and nitrogen to the sunlit upper ocean where phytoplankton grow. More phytoplankton means more carbon absorbed from the atmosphere and more energy at the base of the marine food web. NOAA research has documented this “whale pump” effect across multiple ocean systems. A recovered population of 50,000 animals performs vastly more of this ecological work than a remnant of 150.

For many Aboriginal and Torres Strait Islander communities along the eastern coast, the humpback’s return carries meaning that extends well beyond ecology. These whales hold deep cultural and spiritual significance for coastal First Nations peoples. Their comeback is, for those communities, also a restoration of relationship — one that commercial whaling severed within living memory.

What still needs watching

The population may now be approaching its carrying capacity — the maximum number the environment can sustainably support — which means growth is likely to slow or plateau. And a larger whale population also means more interactions with recreational boaters. Marine scientists urge people on the water to respect minimum approach distances: 100 meters from adult whales, and 300 meters when a calf is present. Even well-intentioned close approaches force whales to burn energy reserves they need for long migrations.

Climate change poses a longer-term question. The Antarctic feeding grounds that eastern Australian humpbacks depend on are warming, with uncertain effects on krill populations — the primary food source for baleen whales in the Southern Ocean. Recovery in one region is not a guarantee of permanent security, and the IWC continues to monitor all subpopulations globally.

Still, what has happened here is a clear demonstration that collapse is not always irreversible. The decisions made by governments and scientists in the 1960s and 1970s C.E. shaped what became possible six decades later — and the eastern Australian humpback now swims in numbers its species has not seen in over a century.

Read more

For more on this story, see: ABC Science

For more from Good News for Humankind, see:

• U.K. cancer death rates down to their lowest level on record
• Ghana’s Cape Three Points marine protected area
• The Good News for Humankind archive on marine conservation

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