Vietnamese authorities are investigating the cause for the mass fish death discovered along several of the country’s central coastline and at local fish farms in recent days.

Last year, Vietnam earned about $8.8 billion from seafood exports, but now officials are investigating whether the problem may have been caused by pollution. They say that signs currently point to the fish having been poisoned by “unidentified substances”.

It’s believed the situation first came to light when farmed fish in the central coastal provinces of Ha Tinh, Quang Tri, Quang Binh and Hue, began dying in great numbers.

“We have never seen anything like it,” aquaculture official Nhu Van Can told Agence French-Presse.

Locals have been asked not to eat the dead fish or feed them to their livestock because of health concerns.

In a statement, environment minister Tran Hong Ha said a team of environmental experts have been dispatched from Hanoi to investigate the phenomenon.

“We must quickly establish whether the fish have died because of environmental pollution,” he said.

Vietnam has a long coastline and much of the country’s export income depends on seafood, including farmed shrimp, catfish and wild-caught tuna.

– TiVi Tuan-san