A new study by U.S. researchers says that recent estimates of declining global fish stocks, including a 2006 report predicting a general collapse by 2048 without significant changes to fisheries management, were overstated because they relied on a flawed methodology. While earlier calculations were based on the amount of fish caught, the new report, published in the journal Conservation Biology, says calculations based on the estimated biomass of available stocks provides a more accurate assessment of the state of global fisheries. The earlier study by researchers at the University of British Columbia calculated that 70 percent of fish stocks had peaked and were now declining as a result of overharvesting, and that 30 percent of species had fallen to 10 percent of earlier numbers. Trevor Branch, a professor at the University of Washington and lead author of the new study, says an assessment based on biomass data reveals that, at most, 33 percent have been overharvested, and about 13 percent have collapsed. While Branch said those numbers are still a cause for significant concern, he said the findings suggest that fisheries management has helped stabilize fish stocks in most regions.