In short:
A new study has found the southern right whale is likely to live for much longer than initially expected.
But the North Atlantic right whale, which lives off the east coast of the US, has had its expected life span reduced.
What's next?
Advocates say hard decisions need to be made to protect all whale species.
At opposite ends of the planet, a tale of two whale species has emerged — giving researchers hope and concern in equal measure.
A global study from Australian, South African and American researchers of baleen whales, a range of filter-feeding species, has changed scientific consensus about their life spans in positive and negative ways.
It found the southern right whale, which populates oceans around Australia, South Africa, New Zealand and Antarctica, can live much longer than initially thought, with an estimated median age of 73 years.
In addition, 10 per cent of southern right whales were estimated to survive past 130 years.
Southern right whales live in the planets southern waters. (Supplied: Andrew Halsall)
Griffith University whale expert and study co-author Dr Peter Corkeron said prior consensus had the species' maximum life span at around 70 years.
"The oldest may well reach around 150 years old or so," he said.
"It means these whales can live much, much longer than we thought, which is kind of cool and exciting."
Off the coast of the eastern United States and northern Europe however, it's a different story for the North Atlantic right whale.
An endangered North Atlantic right whale calf beside its mother, who is tangled in fishing rope near Cumberland Island, Georgia. (AP: Georgia Department of Natural Resources/NOAA Permit #20556)
The study concluded the median life expectancy for this species was just 22 years, with only 10 per cent expected to live past 47.
Dr Corkeron said females typically did not give birth until they were aged between 10 and 18, and only had calves every three to four years.
"If their life is truncated sometime in their 20s, then they're not having enough calves to keep the species going," he said.
Man-made threats
The International Union for Conservation of Nature lists the North Atlantic right whale as critically endangered, with between 200 and 250 mature animals left.
In contrast, the southern right whale is listed under "least concern".
Griffith University whale expert Dr Peter Corkeron. (Supplied: Dr Peter Corkeron)
Dr Corkeron, who is now based in the US, said the ocean off the east coast of the US and Canada, where North Atlantic right whales roam, were some of the most industrialised in the world.
Hundreds of kilometres of fishing lines and thousands of ships traverse the area, creating major threats to the species.
Dr Corkeron said it explained the large life expectancy difference between the two species.
"It's a maze of rope these animals need to get through and there's huge ports coming into the US, there's lots of shipping," he said.
A southern right whale breaching at Fowlers Bay on the Eyre Peninsula, SA. (Supplied: Rod Keogh)
"The Southern Ocean isn't that bad yet and an important lesson from all this work is it's important to keep it that way."
Whale watchers' delight
At Encounter Bay, on South Australia's Fleurieu Peninsula, the whales enter the area to raise their calves as part of a migration channel along Australia's southern coast.
Encounter Whales — Southern Right Whale Conservation and Protection group spokesperson Elizabeth Steele-Collins said locals were passionate about creating a safe space for whales.
Encounter Bay, south of Adelaide, is a favourite spot for whale watchers. (Supplied: Stan Mansas)
She said locals often saw the same whales returning to the area.
"We are very lucky in that the whales that migrate to our coastline have chosen this as one of their breeding areas," Ms Steele-Collins said.
"It's a very important nursery area where the pregnant females come and give birth and raise their calves.
Elizabeth Steele-Collins says it is crucial to make oceans safe for migratory whales. (Supplied: Encounter Bay Right Whale Study)
"We are pretty passionate about wanting to make the waters a safer and quieter place for them to come and meet up with whales to socialise, mate, give birth and raise their young in preparation for the long migration back to Antarctica at the end of each season."
Another calving zone along Australia’s Southern Coast is in Albany, Western Australia.
Edith Cowan University professor for the Centre for Marine Ecosystems Research, Chandra Salgado Kent, said the scientific community was working to fill gaps in knowledge.
A current focus is what's called the 'calving interval', which is the time between the birth of one calf and another.
"On average, a number of years ago it was around every three years, and now it seems to be around four or five years," Professor Salgado Kent said.
"This is something we really, really need to gain insight on, and what might be causing it."
A group of southern right whales mating off Western Australia's south coast. (Supplied: Brett Peake)
As part of the recently launched Right Whale Tracker program, members of the public can contribute photos taken between Albany and Point Ann.
“Using these photographs, we can identify individuals because each individual has a unique callosity pattern, the classify pattern on their head,” Professor Salgado Kent said.
She hopes the program will help improve understanding of the animals, threats and the recovery of the population.
Dr Corkeron said pressure from the public for better policies to protect whales would help conservation efforts.
"What saves whales is people caring about them and the whales meaning something to people.
"Being able to stand on the shore and see a right whale go by … these are magical experiences that hopefully people are making the most of."
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