|Fishermen collect dead fish in the coastal area near Nghi Sơn Oil Refinery and Petrochemical complex in Thanh Hóa Province. – VNA/VNS Photo Duy Hưng|Viet Nam News
THANH HÓA — Tests on water and dead fish have showed that mass fish deaths in the northern province of Thanh Hóa were not related to diseases, said an official.
Lê Văn Sơn, deputy head of Thanh Hóa Province’s Veterinary Bureau, said tests performed by the National Centre for Veterinary Diagnostics indicated ammonia levels and chemical oxygen demand (COD) in water.
Water samples from the coast of Tĩnh Hải, where there was a lot of fish dead, had COD up to five times higher than allowed level while water samples at Nghi Sơn island commune had COD four times than the accepted level and ammonia between 11 and 33 times the allowed level.
Samples of wild fish and fish in floating cages in the two areas were negative for the virus that causes nerve necrosis in sea fish.
Earlier, local authorities blamed the blooming of algae for mass fish deaths.
In early September, locals found about 300kg of dead fish washed ashore near Nghi Sơn Oil Refinery and Petrochemical complex and coastal area near Bắc Yến Hamlet of Hải Yến Commune in Tĩnh Gia District.
Nearly 50 tonnes of fish bred in cages on Nghi Sơn island commune of the same district also died.
An investigation by local authorities showed that seawater samples near the complex and around floating cages of Nghi Sơn Commune were a reddish brown colour. Tests revealed a type of alga named Hairoi-Creratium furca had bloomed.
The provincial People’s Committee proposed Prime Minister Nguyễn Xuân Phúc order the Ministry of Natural Resources and Environment and Ministry of Agriculture and Rural Development send scientists to investigate and to instruct the locality to deal on incident. — VNS