Years of global fisheries decline masked by bad Chinese data. (Environmental Intelligence).

Inflated fish catch reports from China--the world's largest producer of fish--have hidden a decade-long decline in the amount of fish being harvested around the world, according to a new study published in the journal Nature. Scientists tracking the health of fisheries had long expected global fish catch to taper off around 80 million tons, but the U.N. Food and Agriculture Organization's annual compilation of government data reported harvests growing to 86 million tons by the late 1990s--driven largely by reports of steadily increasing yields from China.

"This study reconciles what we see at the local level--failing fisheries--with what is happening at the global level--falling catches," said one of the authors, Daniel Pauly of the University of British Columbia. The fishing industry has long cited increasing harvests as a basis for continued fleet expansion and minimal restrictions on fish catch. "The message here is that our overfishing problems are far more urgent than we even realized," said the University of New Hampshire's Andy Rosenberg, former deputy director of the U.S. National Marine Fisheries Service. "Overfishing is not just a Chinese problem.... This is a global problem."

Suspicious of China's reports of constant growth in fish catch despite data showing that the country's fisheries had been overexploited decades ago, the researchers used a complex computer model to verify the accuracy of the reports. They compared the officially reported catch statistics with levels that were predicted using models of similar oceanographic conditions around the world. The researchers found the Chinese fish-catch data were far higher than could realistically be expected.

The authors conclude that the local officials in China tend to be promoted for production increases and have strong incentive to inflate the catch statistics. "The same entities devoted to monitoring the economy are also tasked with increasing output," said Pauly. "Our studies showed that whatever leaders set as production targets is what [was] officially reported."