Humans risk causing a mass extinction of large sea creatures on a scale never before seen because of overfishing, scientists warned this week.
If the biggest fish vanish, their loss will have serious consequences for other ocean ecosystems, said the study in the journal Science.
"We've found that extinction threat in the modern oceans is very strongly associated with larger body size," said study author Jonathan Payne, a paleobiologist at Stanford University.
"This is most likely due to people targeting larger species for consumption first."
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If a sixth mass extinction occurs -- and some scientists believe it is already under way -- it will look very different than past extinctions caused by asteroid strikes, volcanic eruptions and other natural disasters.
Mass extinctions of the past typically unfolded over thousands of years. The sixth could occur in the span of a human lifetime.
"What is happening in the modern oceans is really different from what has happened in the past," said co-author Noel Heim, also of Stanford.
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Researchers used a database of fossil records to examine the links between extinction threat and traits such as body size for nearly 2,500 mollusks and vertebrates over the past 500 years, and even farther back, as long as 445 million years ago.
Because fishing efforts target the biggest creatures in the sea, the odds of being threatened with extinction have risen significantly for large marine creatures.
"What our analysis shows is that for every factor of 10 increase in body mass, the odds of being threatened by extinction go up by a factor of 13 or so," said Payne.
"The bigger you are, the more likely you are to be facing extinction."
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