A yardstick for estimating ocean fish stocks, including sharks, has warned that some commercial species may be closer to collapse than thought. The study, released on 17/11/10, says figures determining global stocks of some commercially valuable top predators,including sharks, may be unrealistic. Since the late 1990s, scientists and regional management organisations have used catch data to measure changes in the balance of species across so-called "trophic levels." The new study says this technique is not smart enough. Scientists not involved in the study said the findings could revolutionise the way fish populations are measured. "This study makes clear that the most common indicator, average catch trophic level, is a woefully inadequate measure of the status of marine fisheries," said Henry Gholz, an environmental biologist at the US National Science Foundation. Visit http://www.sbs.com.au/news/article/1416597/Global-fish-stocks-lower-than-thought for more details.