|An official of the local Natural Resources and Environment Department's Centre and a local farmer check the quality of oyster before harvesting in central Thanh Hoa Province. — VNA/VNS Photo Anh Tuan
THANH HOA (VNS)— Aquaculture farmers in the central province of Thanh Hoa have seen large numbers of their oysters die since the beginning of last month, leaving them tens of billions of dong out of pocket.
The deaths wiped out 60-80 per cent of oysters raised across hundreds of hectares of aqua farms at coastal communes in Quang Xuong, Hau Loc, Nga Son and Hoang Hoa districts.
Tran Thi Hien, a farmer in Quang Xuong District's Quang Nham Commune, said the oysters died due to polluted water being discharged into Quang Nham's waterways and fishing areas.
In addition, workers harvesting jelly fish have seen the animals die after drifting into tidal areas. Polluted water filled with dead jelly fish also exacerbated the oyster deaths, she said.
More than 30 households raised oysters in Quang Nham Commune. Each household has 1-3ha of oysters. For each hectare, local farmers invest VND450-500 million (US$21,400-23,800) to buy baby oysters and run their business.
Le Van Thuan, a farmer in Hau Loc District's Hai Loc Commune, blamed polluted water discharged in the Kenh De River for the oyster deaths. A number of livestock and poultry farms have been set up along the river.
Thuan said he has 7ha of oysters but dozens of tonnes of them died and he suffered a loss of VND700 million ($33,300).
Cao Thanh Tho, head of the Thanh Hoa Department of Agriculture and Rural Development's Aquatic Product Breeding Division, said samples of water, soil and dead oysters were sent to the Ministry of Agriculture and Rural Development's Department of Animal Health for tests.
No parasite causing diseases were discovered on the oysters.
However, the amount of ammonia in the water and soil exceeded regulated levels by ten times.
Tho said oysters were selling slowly this year so oyster farmers had large stocks in their ponds.
The density of oysters in aqua farms was more than 300 per square metres, while the regulated density is only 150-200 per square metre. The high density resulted in a lack of food for the oysters, which may also have led to the deaths.
An additional factor was that oysters were currently in their reproductive season, a time when their immunity is weak. Meanwhile, the weather in the province has been erratic, said Tho.
Do Quoc Canh, chief of the provincial People's Committee secretariat, said that the committee had received reports and proposals on support for farmers in Hau Loc and Hoang Hoa districts. — VNS