Factories discharging wastewater are likely to be the cause of a sudden rise in deaths of giant stingrays in Samut Songkhram. However, lab test results may not be able to identify the culprits, according to the Department of Pollution Control.

In order to clarify the source of chemicals or toxic substances that killed the giant stingrays, a lab test is required. The results are  expected on Friday,according to the department’s chief.

Samples of water and sediment from different spots along the Mae Klong River, from Samut Songkhram to Kanchanaburi, were collected for tests.

Hopefully these will identify heavy metals and chemicals that may be the cause of the mysterious deaths.

At least 15 stingrays have been found dead since Sept 29.

Even with the lab findings, it may be impossible to single out the factory that discharged the wastewater. Since most factories use the same chemicals, it will be difficult to identify the culprit.

The sudden high death rate has prompted authorities to collect more samples from nearby Don Hoi Lot, a local source of razor clams which have also started dying.

In the meantime,  a vet from Chulalongkorn University who disclosed the rise in deaths of the rare species of rays, insisted tests showed the cause of the deaths was not natural.
Findings by the Animal Health Institute showed toxic contamination in the livers and kidneys of some of the dead stingrays.

Toxins were found to be at 20 times the normal level which showed the kidneys had to work hard to get rid of the toxin from their bodies.

Three survivors which are being nursed also showed similar symptoms of being paralysed, resulting from toxic contamination .

It is impossible to tell what kind of factory released the toxins, but it was clear they were not from the farming sector because the amount of contamination was too high.

Natural causes have also been ruled out and concern is growing as it is estimated that there are only around 150 giant rays left in the river.

Locals believe the deaths were caused by sugar and ethanol-producing factories in Ratchaburi’s Ban Pong district . One plant in Ratchaburi admitted that one of its waste water pipes broke, leading to wastewater discharges into the river.

It is in the process of fixing it. The factory claimed that the incident occurred on Sept 30, but the stingrays started to die a few days before that.

However, locals are convinced the leak started long before that date.

Meanwhile, the Prime Minister has ordered officials to find out the cause of the stingray deaths, saying the rays should be conserved as they are an accurate indicator of the condition of the river.

(With thanks to Bangkok Post)