From the Science Daily
Fishing Throws Targeted Species Off Balance, Study Shows
ScienceDaily (Apr. 21, 2008) — Fishing activities can provoke volatile fluctuations in the populations they target, but it's not often clear why. A new study published in the journal Nature by scientists at Scripps Institution of Oceanography at UC San Diego and colleagues has identified the general underlying mechanism.
Research led at Scripps with a distinguished team of government and international experts (including two chief scientific advisors to the United Kingdom) demonstrates that fishing can throw targeted fish populations off kilter. Fishing can alter the "age pyramid" by lopping off the few large, older fish that make up the top of the pyramid, leaving a broad base of faster-growing small younglings. The team found that this rapidly growing and transitory base is dynamically unstable-a finding having profound implications for the ecosystem and the fishing industries built upon it.
"The data show that fished species appear to be significantly more nonlinear and less stable than unfished species," said Professor George Sugihara of Scripps. "We think the mechanism involves systematic alteration of the demographic parameters-and especially increases in growth rates that magnify destabilization in many ways-which can happen as fishing truncates the age structure."
How exploited and unexploited fish populations differ. (Credit: Image courtesy of University of California - San Diego)
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