North Atlantic right whales currently only live to about 22 years old, but a new study finds they should be able to live to over 130.
Researchers from the University of Alaska, Fairbanks, and other institutions involved in the study say that only 10% of North Atlantic right whales reach the age of 47. The median age at death for the species is about 22.
In contrast, southern right whales, a closely related species, have a median lifespan of about 73 years, and 10% are expected to live to nearly 132 years of age.
“So we can compare how North Atlantic right whales are doing, compared to these other species, and just see there's something terribly wrong,” said lead author and researcher Greg Breed. “And I think the terribly wrong things are staring us in the face.”
Breed says entanglements in fishing gear, boat collisions, and climate change are responsible not only for driving the North Atlantic population down to about 370, but for right whales’ relatively short lives today.
The paper, which relies on models based upon long-term sightings data, also argues that centuries of whaling have culled all of the older whales from the North Atlantic right whale population, so contemporary whale data does not reflect actual longevity potential.
“It could be another hundred years before old individuals are seen again,” Breed said, “or even exist again for us to detect them.”
The consequences of a young population, researchers said, are serious.
“Animals that live a long time can withstand annual environmental changes, including variation in prey, habitat, oceanography, and climate. Living through hard times allows animal to conserve resources to survive and reproduce when things are better,” said Scott Kraus, a research scientist emeritus from New England Aquarium. WCAI asked him to independently review the paper.
The shortened lifespans mean that North Atlantic right whales, as a species, are suffering in multiple ways. With few or no older whales in the populations, there’s less "generational knowledge" about how to stay alive as conditions change. And short lifespans result in dramatically lower potential for reproduction and population replenishment, especially compared to Southern right whales.
“Southern right whales are becoming mature at 12 just like the North Atlantic right whales but they're living to be 74 and they’re calving every three years. Well, doing the math, an average individual is going to have … like 15 [calves] versus two, three, or four for the North Atlantic right whale,” Breed said. “And that just has a huge difference in population trajectory.
Kraus described the paper, published on Friday in the journal Science Advances, as a “convincing case” that pushes “well past prevailing wisdom on whale longevity.”
“This paper is an excellent and quantitative reminder of the unintended cost of doing business in the ocean," he said, "and an exclamation point on the steady drumbeat of scientific information emerging over the last decade showing North Atlantic right whales heading for extinction.”
