March 12, 2013 A dead pig lies in a dirty tributary of the Yangtze River in a village in Yichang, in central China's Hebei province, some 1,200 kms from the eastern city of Shanghai. AFP PHOTO

Online frustration is rising along with the reported number of decaying pig carcasses found in Haungpu river in Shanghai. On Monday state media reported the number of recovered pigs, which were first found March 8, had reached 13,000. Now many Chinese netizens are questioning why anger on the web has not translated to demonstrations in the streets.

The carcasses have been traced to farms in neighbouring Zhejiang province, an area previously implicated in food and farm safety issues. Samples of the dead animals have tested positive for a common swine disease that is not passable to humans. The Chinese government insists that tap water from the river, which provides 22 percent of Shanghai's supply, is still safe.