Whales are not only the biggest animals on the planet, but they’re among the longest-lived, too. A new analysis reveals that right whales can live for more than 130 years, almost twice as long as previously thought.
Right whales are filter-feeding baleen whales that were hunted almost to extinction during the height of the whaling industry. As such, some of the most basic information about them remains unknown, including how long they can live.
To answer some of these questions, researchers at the University of Alaska Fairbanks analyzed 40 years’ worth of data collected by right whale identification programs. The study focused on two species: the Southern right whale, which lives in the oceans around Antarctica, Australia, South America and South Africa; and the North Atlantic right whale, which can be found off the eastern coast of the United States and the northwestern edge of Europe.
The team used this data to create what are known as survivorship curves – essentially, plotting a graph of how many individuals survive to each age. This can be used to infer the average age and likely maximum lifespan of a population.
It was long thought that both species of right whale lived to 70 to 75 years of age at most, but the new study found that it was much longer. Southern right whales were calculated to have a median lifespan of around 73 years, while more than 10% of the population was expected to live beyond 132 years.
Sadly, North Atlantic right whales didn’t fare so well. Their median lifespan was a mere 22 years, with 10% making it beyond 47 years.
“North Atlantic whales have unusually short lifespans compared to other whales, but this isn’t because of intrinsic differences in biology, and they should live much longer,” said Greg Breed, lead author of the study. “They’re frequently tangled in fishing gear or struck by ships, and they suffer from starvation, potentially linked to environmental changes we don’t fully understand.”
The team cites similar reasons as to why the maximum lifespans of both species of right whale were underestimated. Biologically, there should be very old individuals in both populations, but as the team notes, whaling only ended about 60 years ago, meaning the oldest animals had to have survived some 40 years of threats from humans before that.
“We didn’t know how to age baleen whales until 1955, which was the very end of industrial whaling,” said Breed. “By the time we figured it out, there weren’t many old whales left to study. So we just assumed they didn’t live that long.”
It’s important to understand how animals like whales age, on both the individual and community levels. Older members of a group teach the younger generations crucial survival skills, so losing these mentors can affect the entire species’ recovery. And that recovery is already a long process for a species with a slow-motion breeding cycle like whales.
The research was published in the journal Science Advances.
Source: University of Alaska Fairbanks
