While so closely related that only quarter of a century ago, they were considered to be the same species, there’s a little more than just distance that separates the southern right whale from its close cousin, the North Atlantic right whale. Primarily, that would be a newly recorded lifespan enjoyed by the southern right whale of up to almost five times that of its northern hemisphere counterpart.

It’s been a project filled with revelations for researchers behind the latest findings that southern right whales have lifespans that stretch well past 100 years, with some 10% of the species living even past 130 years, with records of some living right up to their 150th birthday. 

What this means is that – theoretically – a southern right whale could be swimming the ocean’s waters today having been born in the year 1875 – the same year the telephone was first patented and the Civil Rights Act was affirmed. 

The research – led by Greg Breed (associate professor of quantitative ecology at University of Alaska Fairbanks) and Peter Corkeron (adjunct senior research fellow, Centre for Planetary Health and Food Security, Griffith University) and published this month in Science Advances – concluded that this newly revised lifespan for the southern right whale is almost double the 70 to 80 years they were conventionally believed to have.

In stark contrast, the closely related North Atlantic right whale were also thought to have a maximum lifespan of around 70 years. However, Breed and Corkeron found that the current average lifespan of this critically endangered species is only 22 years. In fact, rarely does a North Atlantic right whale today live past the 50-year mark.

As positioned in their paper Extreme longevity may be the rule not the exception in Balaenid whales, Breed and Corkeron indicate that the very short lifespan of the North Atlantic right whale “almoast certainly results from the well-documented anthropogenic and ecological factors” that greatly increase the “mortality hazard” across age classes.

In simple terms, the paper’s authors attribute the stark difference in lifespan and longevity to human-caused mortality, mostly from entanglements in fishing gear and ship strikes.

North Atlantic right whales experience their lowest annual mortality hazard in their fifth year of life. In that year, they have an expected 2.56% chance of dying. By comparison, southern right whale hazard in the fifth year of life is only 0.5%. Their annual mortality hazard does not exceed 2.56% until they reach the ripe old age of 102 years.

These new age estimates were made using photo identification of individual female whales over several decades. It’s well-established that individual whales can be recognised year after year from photographs. Recent headlines were made when new ground in whale identification was broken by deploying a type of facial recognition technology to assess individual whales by markings on their flukes. It led to the identification of the whale that broke all known records of whale migration by some considerable distance.

However, when whales die they stop being photographically ‘resighted’ and disappear. Using these photos, the researchers behind this study were able to develop what has been called ‘survivorship curves’ by estimating the probability whales would disappear from the photographic record as they aged.

“From these survivorship curves, we could estimate maximum potential lifespans,” Breed and Corkeron wrote in a piece for The Conversation.

It’s hoped that, with this new understanding of the lifespan of southern right whales, conservation and management strategies can be better planned, especially given the expected impacts of climate disruption.

“Understanding how long wild animals live has major implications for how to best protect them,” write Breed and Corkeron. “Animals that have very long lifespans usually reproduce extremely slowly and can go many years between births.

“Baleen whales’ life history – particularly the age when females start breeding and the interval between calves – is strongly influenced by their potential lifespan.”

The pair say the research now also poses larger questions over the potential lifespans for further baleen whale species, including blue, fin, sei, humpback, gray, and sperm whales. 

Breed and Corkeron continued: “Industrial whaling, which ended only in the 1960s, removed old whales from the world’s whale populations. Though many whale populations are recovering in number, there hasn’t been enough time for whales born after the end of industrial whaling to become old.”

25 years ago, scientists working with Indigenous whale hunters in the Arctic showed that bowhead whales could live up to and even over 200 years. Like right whales, before this analysis, researchers thought bowhead whales lived up to about 80 years and that humans were the mammals that lived the longest.

“It’s possible, even likely, that many other whale will also prove to have long lifespans,” said Breed and Corkeron.

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