The municipal authorities said the retrieved pigs from the river would be collected and handled in a harmless way.
According to the labels pinned in the pigs' ears, meant to trace their information, indicated they came from the upstream waters of the river. Authorities were conducting coordinated efforts to stop the dumping of dead pigs from the source.
Media reports said the pigs mainly came from Shanghai's neighbouring Jiangsu and Zhejiang provinces.
Meanwhile, the city's water supply bureau said the water quality of Shanghai had not been affected by the floating dead pigs. "The data of water quality are all within the normal range."