Fishing throws species off balance

Date: 1/10/2008

A new study by scientists at Scripps Institution of Oceanography, University of California, demonstrated that fishing can alter the ‘age pyramid’ by lopping off the few large, older fish from the top of the pyramid, leaving a broad base of faster growing, small younglings. This rapidly growing and transitory base is dynamically unstable. These many smaller fish with the same initial biomass as the larger fish cannot average out the environmental fluctuations, amplifying them through higher turnover rates that promote boom and bust cycles. Fishing typically extracts the older, larger members of a targeted species, and fishing regulations often impose minimum size limits to protect the smaller, younger fish. ‘That type of regulation, is exactly wrong’ said George Sugihara of Scripps. ‘It’s not the young ones that should be thrown back, but larger older fish that should be spared.  Not only do the older fish provide stability and capacitance to the population, they provide more and better quality offspring.’

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