Mass lobster deaths in south-central Vietnam remain a mystery

The change in conditions is alleged to have depleted the bottom water oxygen level, causing the crustaceans to die from aquatic hypoxia, according to initial statements by local officials.

Since then, over 770,000 lobsters from farms in Phu Yen have died, accounting for nearly 40 percent of the province’s commercially farmed lobster population.

According to a report by Phu Yen’s Department of Agriculture and Rural Development, long hot days prior to the deaths had resulted in increased organic decomposition along the bottom water layer in Xuan Dai Bay.

The warmer water created conditions that allowed algae to bloom underwater, the department said, using up oxygen in the area at night and causing the lobsters to die from aquatic hypoxia.

Inspections by local authorities also found that lobster farmers had installed three times as many lobster cages as were approved by the provincial planning department for aquaculture, according to Luong Minh Son, deputy Party chief of Phu Yen.

“There are obviously extreme risks involved when you completely disregard official planning, and in reality there has been density-related damage [to the lobster population] over the past few years, though never on the scale as we’re seeing this year,” Son said.

Local lobster farmers, however, insist that only pollution caused by the illegal dumping of wastewater from nearby factories could have killed so many lobsters at once.

According to Trinh Thi Bo, owner of a lobster farm in Phu Yen, oxygen depletion-related lobster deaths have occurred in the past, but only in very small numbers.

There was no way aquatic hypoxia could have caused these lobsters to die in such droves, Bo said.

Bo’s claim was echoed by fellow farm owner Nguyen Van Tao, who demanded an investigation into the wastewater discharged by factories in the area to determine whether human error was at fault.

Tran Huu The, deputy chairman of the Phu Yen People's Committee, took responsibility for the lack of management that had resulted in the unusually high density of farmed lobsters in the province.

He said huge profits earned from lobster farming had led local farm owners to disregard planning and raise lobsters in numbers far exceeding the recommended level.

Authorities have, however, collected water samples from local factories and food processing facilities to be tested for any signs of harmful pollutants, The confirmed.

The Ministry of Agriculture and Rural Development and the Ministry of Natural Resources and Environment have agreed to assist the investigation and discover the cause of the lobster deaths.