A oyster farm in Vân Đồn District, northern Quảng Ninh Province. Aquaculture farmers in the province have seen large numbers of their oysters die since last October, leaving them in financial difficulties.— Photo baoquangninh.vn

QUẢNG NINH — Aquaculture farmers in the northern province of Quảng Ninh have seen large numbers of their oysters die since last October, leaving them in financial difficulties.

The deaths wiped out 50-60 per cent of oysters raised across hundreds of hectares of aqua farms at Hải Hà district’s Quảng Minh, Quảng Điền and Phú Hải communes, according to the statistic of the districts’ Agriculture and Rural Development Department.

The test results of the Veterinary Department showed that a parasite named Perkinsus and Vibrio bacterium were the cause of the massive die-off of oysters. Another reason for the oyster deaths is that the baby oysters were not tested for these conditions before rearing, the department’s officials said.

The death of the oysters occurred since last October, said Bùi Văn Toàn, head of the aquaculture breeding cooperative in Quảng Minh commune. Nearly 200ha of oysters died before local farmers could harvest them.

Vũ Thị Thạch, a farmer in Quảng Minh commune, said that since the oyster deaths began a few months ago, she has to collect oyster shells every day.

“I can not collect them all, because the number of dead oysters is too large,” she told Nông Thôn Ngày Nay (Today Countryside) newspaper.

“I invested heavily in oysers. But I lost all of them,” she said.

The high density of breeding resulted in a lack of food for the oysters, which may also have led to the deaths, according to the provincial Agriculture and Rural Development Department. An additional factor was that oysters were in their reproductive season, a time when their immunity is weak.

Meanwhile, the weather in the province has been erratic, the department said.

The number of deaths increases every day because households can not collect the dead oysters quickly enough to avoid polluting the breeding areas, according to the department.

The deaths leave farmers tens of billions of đồng out of pocket.

Nguyễn Văn Công, director of the Agriculture and Rural Development Department, said households should remove all dead oysters from breeding areas as fast as possible. They should also stop oyster farming for at least 3 to 4 months, to restore and improve oyster habitat. To avoid further losses, farmers need to implement breeding techniques and use baby oysters which are tested for disease before rearing. — VNS