Agriculture officials are investigating what killed a massive number of clams at nearly 200 hectares of farms in central Vietnam, but they suspect toxic waste was the culprit.
A source from the agriculture ministry said tests found no signs of diseases at the clam farms in Ha Tinh and Nghe An Province.
Farmers in Ha Tinh said the clams began to die more than a month ago after water at the farms suddenly turned reddish.
Clam shells are washed to the shore, covering the coastline. Farmers estimate that losses could amount to US$470,000.
The same situation has happened with more than 100 hectares of clam farms in the neighboring Nghe An.
Tests by the ministry found no pathogenic elements on the clams or water in the area.
But they detected very high level of lead in the water, 3,660 times higher than the permitted level.
An official said someone must have secretly dumped toxic waste into the water.