APRIL 29 2011 02:25h

World fish stocks said improved

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SEATTLE, April 28 (UPI) -- Researchers at the University of Washington say a new method for measuring biomass shows worldwide fish stocks are more stable than previously thought.

Lead researcher Trevor Branch and his team, writing in Conservation Biology, argue previous estimates were flawed by inappropriate use of trends in catches.

"Estimates of fishery status based on catches suggest that around 30 percent of fisheries are collapsed and 70 percent are overexploited or collapsed," Branch said. "Our assessment shows that the data are seriously biased, and that instead we should be looking at biomass data."

Biomass measurements, he said, indicated a much smaller proportion in these categories -- 12 percent collapsed, 26 percent overexploited or collapsed -- and that status trends are stable.

"Species which are targeted by fishing fleets are divided into stocks, a division of species into units based on political boundaries, genetic divergence, and biological characteristics," Branch said. "The depletion of these stocks has important implications for ecosystem biodiversity; however methods of measuring depletion vary greatly."

Branch said his analysis suggests fisheries management has led to stabilization, and even recovery, of fish stocks in most regions.

"Instead of focusing on what we take out of the oceans (catches), we should be examining the actual state of the ecosystem (biomass data)," Branch said.