The large number of pig carcasses dumped in rivers in Jiaxing, Zhejiang province, was due to a lack of proper disposal facilities for animals that had died on farms from illnesses or the weather, not an outbreak of disease, pig collectors and villagers say.
Jiaxing, about 100 kilometres upstream from Shanghai, is the suspected source of the nearly 6,000 dead pigs retrieved recently from the Huangpu River, which flows through the heart of the country's largest city.
A government crackdown last year on an underground market for dead pigs that were butchered for illegal pork may also have contributed to the rise in dumping, farmers from Jiaxing's Yongfeng village said. Pig sales are the biggest contributor to villagers' incomes.
Gu Jinlin , who collects dead pigs from the village's farms, said the number of animals that had died had risen at the start of the year, but the village lacked the means to dispose of all the carcasses properly.
An employee of the village committee, Gu said he collected 40 to 50 dead pigs a day and carted them to "non-hazardous treatment pits" - 100-cubic-metre holes, five metres deep, with concrete walls.
He said "non-hazardous treatment" meant throwing the carcasses into the pits and covering them with lids. He said there were five pits in the village, and the village committee was looking for land to build another one. Zhejiang's agriculture department had previously said that most of the dumped pigs had frozen to death.
Gu and another villager who declined to be named said some dead pigs used to be sold to illegal dealers but a government crackdown last year had slashed the number of such transactions.
"On the black market, a dead pig could sell for several dozen yuan," Gu said. "They were made into stuff like meat sauce. Last year some dealers were arrested."
Another villager said the sale of dead pigs used to be common, but had stopped recently.
A report by the local news portal cnjxol.com  said a Jiaxing court had heard a case in October in which 17 people faced charges of buying the carcasses illegally and butchering them for pork that was sold to the public.
One of the suspects allegedly made about 8 million yuan (HK$9.9 million) in profit from the business, it said.
An official from Jiaxing's animal husbandry and veterinary bureau said on Tuesday that the local government gave farmers an 80-yuan subsidy for each dead pig, but villagers said they never received the payments.
In an online interview yesterday, Jiaxing's rural economic bureau said the city was not the only source of carcasses in the Huangpu River, but did not say which other places were to blame.
The bureau insisted that no epidemics had occurred among pigs in the area, which raised over 7 million animals last year, including more than 300,000 that had been disposed of through "non-hazardous treatment". About 70,000 pigs had died this year due to poor farm practices and weather, it said.
Shanghai's government said yesterday it had sped up construction of barriers on the Huangpu River to prevent more pigs from floating downstream.
Water quality was still in line with national standards and the number of dead pigs retrieved had dropped on Tuesday, it said.