Nature & Environment
How Long Great White Sharks Live: New Age for Conservation Efforts
Catherine Griffin
First Posted: Jan 10, 2014 07:37 AM EST
How long can sharks live? Quite a while, it turns out. Scientists have discovered that great white sharks grow much slower and live significantly longer than previously thought. The findings could have implications for conserving this species in the future.
Estimating age in white sharks can be challenging. These creatures are the top predators throughout the world's oceans, and finding acceptable specimens can be difficult. Not only that, but age determination in fish usually relies on analyzing growth increments in mineralized tissue; think of it like counting the rings of a tree. The vertebrae in great white sharks, though, have bands that are narrower and less distinct than in other species. In addition, the bands don't necessarily signify annual growth.
"Traditionally, ageing sharks has relied on the assumption that band pairs are annual," said Lisa Natanson, one of the researchers, in a news release. "In many cases, this has proven correct for part or all of a species life, however in more and more cases this is being disproven."
In order to get around these issues, the researchers took advantage of radiocarbon produced by thermonuclear device testing done during the 1950s and 1960s. Radiocarbon mixed from the atmosphere into the ocean and was incorporated into the tissues of marine organisms living at the time. The rise in radiocarbon gave researchers a specific spot in time pinpointed in the vertebra layers, which could then be used as a "time stamp" to help determine an animal's age.
So what did the scientists find? After analyzing vertebrae from four females and four males from the northwestern Atlantic Ocean, the researchers found that the largest male shark was 73 years old. The largest female was 40 years old.
"Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies," said Li Ling Hamady, one of the researchers, in a news release. "Understanding longevity of the species, growth rate, age at sexual maturity and differences in growth between males and females are especially important for sustainable management and conservation efforts."
The findings are published in the journal PLOS One.
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First Posted: Jan 10, 2014 07:37 AM EST
How long can sharks live? Quite a while, it turns out. Scientists have discovered that great white sharks grow much slower and live significantly longer than previously thought. The findings could have implications for conserving this species in the future.
Estimating age in white sharks can be challenging. These creatures are the top predators throughout the world's oceans, and finding acceptable specimens can be difficult. Not only that, but age determination in fish usually relies on analyzing growth increments in mineralized tissue; think of it like counting the rings of a tree. The vertebrae in great white sharks, though, have bands that are narrower and less distinct than in other species. In addition, the bands don't necessarily signify annual growth.
"Traditionally, ageing sharks has relied on the assumption that band pairs are annual," said Lisa Natanson, one of the researchers, in a news release. "In many cases, this has proven correct for part or all of a species life, however in more and more cases this is being disproven."
In order to get around these issues, the researchers took advantage of radiocarbon produced by thermonuclear device testing done during the 1950s and 1960s. Radiocarbon mixed from the atmosphere into the ocean and was incorporated into the tissues of marine organisms living at the time. The rise in radiocarbon gave researchers a specific spot in time pinpointed in the vertebra layers, which could then be used as a "time stamp" to help determine an animal's age.
So what did the scientists find? After analyzing vertebrae from four females and four males from the northwestern Atlantic Ocean, the researchers found that the largest male shark was 73 years old. The largest female was 40 years old.
"Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies," said Li Ling Hamady, one of the researchers, in a news release. "Understanding longevity of the species, growth rate, age at sexual maturity and differences in growth between males and females are especially important for sustainable management and conservation efforts."
The findings are published in the journal PLOS One.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone