Researchers have been tracking southern right whales off the Great Australian Bight for 50 years, revealing a decline in population with only 520 whales counted this year compared to 646 last year. The number of whales travelling solo has nearly doubled since 2023, while the calving cohort cycle is extending from every three years to every five. Long-term data suggests that southern right whale populations are stagnating, with indications of dropping calving rates and a 20% drop in individual sightings compared to a decade ago. Dr. Claire Charlton attributes the change in whale behavior to changes in water temperatures affecting marine food webs and breeding patterns.
Written by the local model on 2026-09-06,
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Story summary
For the past 50 years, researchers from Murdoch University have been tracking the migratory patterns of southern right whales off the Great Australian Bight. This year's census, led by senior researcher Joshua Smith, recorded a total of 520 whales, including 235 cow-calf pairs, which is a significant change in their breeding patterns. In contrast to last year's count of 646 individual whales and 304 calves, this year's numbers show that nearly twice as many whales are traveling solo rather than with calves. The research also reveals that the calving cohort cycle, or the time between births, has extended from every three years to every five years. This change is a key finding in understanding the population dynamics of southern right whales. According to Dr. Smith, there has been a "stalling" in the population since 2011, with a 20% drop in individual sightings compared to a decade ago.
Written for “Whales Found in Great Australian Bight” on 2026-09-07,
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In short:
Half a century of aerial tracking off the Great Australian Bight has revealed insight into the breeding patterns of the endangered southern right whale.
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century → reveal → whale
This year's data show nearly twice as many whales are travelling solo rather than in cow-calf pairs, compared to 2023.
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whales → show → 2023
Long-term data reveals the calving cohort cycle is extending from every three years to every five.
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cycle → reveal → five
Each winter, southern right whales move north from the Antarctic to the southern Australian coastline to breed in warmer waters.
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whales → move → waters
For 50 years, researchers have been tracking the great whale's migratory patterns between Fremantle in Western Australia to Ceduna on South Australia's far west coast, revealing a key change in their birthing cycles.
Murdoch University senior researcher Joshua Smith, who led this year's census, recorded 520 whales across the south-west, including 235 cow-calf pairs.
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who → track → pairs
The figures show a decline from last year's count of 646 individual whales and 304 calves, and a 20 per cent drop in individual sightings compared to a decade ago.
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figures → show → sightings
"Since 2011, there has been a stalling in the population,"Dr Smith said.
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Smith → say → 2011
Australian Right Whale Research Program chief scientist Claire Charlton has conducted land-based monitoring from the head of the Great Australian Bight Commonwealth Marine Park on the Yalata Indigenous Protected Area.
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Charlton → conduct → Area
She said that while total whale sightings were down this year, the Bight still saw a gathering of 61 mother-calf pairs, making up more than 30 per cent of the south-west total.
"It's a conservation success story for the marine park," Dr Charlton said.
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Charlton → say → park
Alongside breeding pairs, the whale census tracked about 50 unaccompanied whales without calves.
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census → track → calves
Dr Smith said while traditional calving sanctuaries, including the Head of Bight and Israelite Bay in Western Australia, remained active, overall activity was unusually quiet.
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activity → say → Australia
Increased intervals between whale calving
Dr Smith said the long-term data revealed southern right whale populations were stagnating.
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populations → increase → calving
"The population isn't really increasing to any extent," he said.
"
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he → increase → extent
There's actually indication that calving rates are dropping."
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rates → be → ?
A decade ago, it was thought whale breeding cycles restarted every three to four years.
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cycles → think → ?
Dr Smith said one of the major findings in the long-term data was that those intervals were now pushing every five years.
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intervals → say → data
"The three-year cycle that we used to always pride ourselves on is extending," he said.
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he → use → ourselves
Dr Smith said it was evident through strong highs and lows from year to year.
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it → say → year
"It takes 10 years and maybe two or three cycles of a reproductive female coming back to the coast before you can really see what's going on in the population," he said.
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he → take → population
"That's why it's so important to have this long-term data.
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it → have → data
"
Why the change in whale behaviour
Dr Charlton said changes in water temperatures were impacting marine food webs and breeding patterns.
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changes → say → webs
"Their breeding cycle is directly linked to their body condition and their body condition is linked to their feeding success," she said.
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she → link → success
She said as the ocean warmed, there were fewer sea lice, which leads to fewer krill to feed the great whales.
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which → say → whales
"[Whales] are also under pressure from krill fisheries and have less prey available.
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prey → have → fisheries
That's causing stresses to them and their long-term recovery."
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That → cause → them
She said they may hold off breeding due to food scarcity, explaining why breeding cycles were pushing to the five-year mark.
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cycles → say → mark
While the whale survey was conducted off the Great Australian Bight, Dr Charlton said attention should also be paid to whale populations in Victoria and New South Wales.
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attention → conduct → Victoria
"South-eastern populations of southern right whales have experienced low sightings and no female calf pairs," Dr Charlton said.
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Charlton → experience → sightings
Hotspots for southern rights
Dr Smith said hotspots for populations were in Israelite Bay, Point Ann and Point Charles along the south coast of WA and in SA at the head of the Bight.
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hotspots → say → Bight
Whaling in the 20th century reduced the population, but increased sightings in Western Australia in the 1970s led scientist John Bannister to begin an aerial survey to observe their recovery in 1976.
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sightings → reduce → 1976
The Western Australian Museum's annual southern right whale aerial survey continues to paint a picture of changing whale behaviours off the continent's south coast.
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survey → continue → coast