Authorities told to tackle water pollution to prevent deaths of aquatic animals

Dr Nantarika Chansue, head of the Veterinary Medical Aquatic Animal Research Centre at Chulalongkorn University, said yesterday it was too late to do anything about the recent deaths of giant freshwater stingrays but authorities could work to restore the water quality in the Mae Klong River.

Since the end of September, there have been several reports of dead stingrays being found in multiple locations along Mae Klong River and its tributaries in Samut Songkhram. As of the latest count, 51 dead stingrays have been found since last month. 

“I can’t help but think that unless the prime minister orders relevant agencies to tackle this problem, there will be not be an urgent war room set up. Right now there is very low chance of determining the source of pollution and we should prioritise relief and prevention,” Nantarika said 

“It just like our home is on fire – we should extinguish the fire first, before finding the cause.”

Samut Songkhram Governor Kanchat Tansathian admitted that an emergency response centre had been set up late in his province, but added that relevant agencies and the entire public sector would now tackle the problem and determine the stingrays’ cause of death.

“This incident happened very suddenly and we admit that we were quite slow to react to the problem, but now every related agency in the province is ready to solve this problem together,” Kanchat said.

He added that testing of water and soil samples from the river was ongoing, so it was too early to determine the source of pollution or try to punish the responsible actors.

“We are now working to find what is the reason for the mass deaths, but at present no one will be blamed,” he said.

Kanchat added that the recent mass die-off of razor clams was due to a seasonal plankton bloom and unrelated to the stingrays’ deaths.

There has been speculation that pollution from factories upstream in Ratchaburi caused the stingrays’ deaths, while the main current hypothesis is that the fish were killed by low dissolved oxygen levels in the river caused by pollution and toxic chemicals.

However, Nantarika said she was sure that the stingrays had ingested toxic substances.

“The autopsy of the dead stingrays and symptoms of three surviving stingrays indicate that the stingrays were exposed to unknown toxic substances, which affected their kidneys and gums. However, it is very hard to identify these substances and the sources right now,” she said. 

Bandhit Pansawat, a coordinator for the Self-Managed Samut Songkhram Group, said the situation was improving and that yesterday was the first day this month with no new reports of dead stingrays.

“The last report of dead stingrays was on Tuesday and the latest count of stingrays is now 51. This is the highest mortality rate for this rare fish species that I can remember, because normally there were only two or |three dead stingrays seen each year,” Bandhit said.