Chinese fishing boats catch about $11.5 billion worth of fish outside their own waters and most of it goes unreported, a Canadian-led study suggests. Fisheries scientists at the University of British Columbia said they estimate China's foreign catch is 12 times larger than what it reports to the United Nation's Food and Agriculture Organization, the international agency that tracks global fishing operations. Analyzing the type of fishing vessels used by Chinese operators and their catch capacity, the researchers estimate Chinese foreign fishing at 4.6 million tons per year, taken from the waters of at least 90 countries -- including 3.1 million tons from African waters, mainly West Africa, a university release said Wednesday. "China hasn't been forthcoming about its fisheries catches," study co-author Dirk Zeller said. "While not reporting catches doesn't necessarily mean the fishing is illegal -- there could be agreements between these countries and China that allow fishing -- we simply don't know for sure as this information just isn't available." Studying and quantifying global catches is vital to ensuring the sustainability of fisheries, researchers said. "We need to know how many fish have been taken from the ocean in order to figure out what we can catch in the future," study lead author Daniel Pauly of the university's Sea Around Us Project said. "Countries need to realize the importance of accurately recording and reporting their catches and step up to the plate, or there will be no fish left for our children."