Endangered southern right whales could live twice as long as scientists think, a new study shows. these Whales The study found that its lifespan often reaches 130 years, and may reach 150 years.
Southern right whales (Australian Eubalina) are found throughout the Southern Hemisphere but were heavily hunted until the 1960s, when the International Whaling Commission began monitoring whaling. Ban on commercial whaling. Consider them people in the whaling industries The “right” kind of whale They are hunted because they move slowly, float when dead, and have a high yield of profitable oil and whale bones.
Previously, scientists thought the average life expectancy of southern right whales was about 70 years. But these are marine mammals They are closely related to bowhead whales, and Longest-lived mammals It was never recorded Cape Alaska (Ballina Misquitos) is estimated at 211 years.
“Given everything we know about the life history of these species, I assumed they already existed [the Southern right whales] should live longer,” study co-author Greg BreedThe quantitative ecologist at the University of Alaska Fairbanks told Live Science.
However, estimating the longevity of whales can be difficult.
Scientists typically use ring growth layers on teeth, which, like tree rings, are placed annually. However, many baleen whales do not have these growth layers. Even if this occurs, tissue erosion and missing specimens can skew the estimate.
But the biggest challenge is that commercial whaling only ended about 60 years ago. So whales older than that would have survived many decades of intense whaling to become centenarians. It is likely that only a few individuals reached their full lives.
To overcome these challenges, Breed and his team analyzed tracking data for right whales in the South and North Atlantic (Eubalina Glacier) collected over four decades. From 1979 to 2021, scientists led Peter Best At the University of Pretoria in Cape Town, she surveys female southern right whales on the southern coast of Africa by photographing them every year. Through this survey, the scientists who conducted the new study identified 2,476 females, 139 of whom had known birth years. Breed and his team used this data to construct a survival curve. They noted the age and rate at which an individual disappears from the population. From there, they can estimate the proportion of the population that lives to a certain age.
“It’s the same thing that the Social Security Administration uses to evaluate the longevity of someone who is now 65, and their average lifespan from that point on, not from birth,” Breed said.
The researchers compared these results to records of North Atlantic right whales collected around the same time and made available by the Foundation Federation of North Atlantic Right Whalesa non-profit conservation group.
The analyzes are described in a study published December 20 in the journal Advancement of scienceHe revealed that southern right whales have an average lifespan of 70 to 75 years. One in 10 individuals were expected to live beyond the age of 130, confirming Breed’s initial hypothesis. In comparison, North Atlantic right whales have a relatively short lifespan with an average lifespan of 22 years, and only a few live past the age of 45.
“Not because they are so different biologically, but because they have experienced a much higher degree of human-caused or man-made mortality than southern right whales,” Breed said. North Atlantic right whales often get stuck in fishing gear, especially lobster and crab pots anchored to the ocean floor, he said.
Even at current estimates, southern right whales live only half the lifespan of bowhead whales. Researchers believe this is related to right whales living in places free of sea ice.
“There is reason to believe that living on ice can contribute to longevity,” Breed said. For example, Killer whales (Ursinus orca) or killer whales, which Catch both heads And southern right whalesThey really hate going on sea ice. “So bowhead whales can always get to the sea ice, and killer whales won’t follow them,” Breed said. As sea ice disappears, the bowheads may disappear They are no longer able to avoid predation.
Understanding an animal’s lifespan affects the way we think about conservation, especially its reproductive pattern and potential longevity after whaling, Breed said. In the future, he and his team would like to investigate the numbers of elderly individuals that survive whaling and study how whale populations recover to pre-whaling levels.
