No small discrepencyA recent study estimates how much fish China's distant-water fleet has been catching around the world between 2000 and 2011, and the numbers are shocking. During that decade to 2011, China has reported to the Food and Agriculture Organization of the United Nations an average yearly overseas catch of 368,000 tonnes. The actual numbers, according to the authors of the study who did detective work around the world, are closer to 4.6 million tonnes a year, over 12 times (!!!) the reported amount. Enough to make a big difference in the health of global fisheries, and enough to make any models of those fisheries significantly off.
Fisheries scientists find the latest assessment startling. “So that’s where my fish were going!” says Didier Gascuel at the European University of Brittany in Rennes, France, who is a member of the scientific committee that advises Mauritania and the EU on fishing agreements. Year after year, Mauritanian populations of bottom-dwelling species such as octopus, grouper and sea bream have remained stubbornly low — a sign of overfishing by bottom-scraping trawlers, he says. “We had no idea the Chinese catch was so big and of course we never included it our models,” he says. (source)
Why is it so hard to know how much fish China's long-distance fishing fleet is catching? Mostly because they keep contracts with other countries - especially African ones - secret, and they often operate with local flags on their ships. They also don't bring it all back to China; a lot is sold locally. Chinese ships have been found operating around countries where they officially report no catch.
All of this just makes me wonder how many other countries are doing the same. Maybe not on the same scale, but it all adds up...