With no immediate cause ascertained for the death of an Irrawaddy dolphin calf in the Mekong River in Stung Treng province, conservationists on Sunday requested the World Wide Fund For Nature (WWF) to investigate further.

The dolphin was found floating on the river on Saturday in Thala Barivat district’s Preah Romkil commune.

Dorn Pan, Anlong Svay village chief and deputy head of the river guard for dolphin preservation in the Anlong Chheuteal area, said after initial assessments, there were two possible factors which had contributed to its death – illegal fishing using explosives or electronic shocking devices, and being surprised by a tourist boat.

“When a dolphin is born, the mother needs to help the calf to move, grow, swim and breathe because newborn dolphins do not know how to breathe properly."

“Some tourist boats do not understand how to navigate closer to the dolphins in a safe way. They try to chase the dolphin to watch it closely which interferes with the mother nurturing of her calf,” he said.

Preah Romkil commune police chief Loeng Thary said a group of fishermen found the dolphin floating on the river at about 6:30am on Saturday. He said the calf’s body did not show any sign of injuries that would suggest illegal fishing might have caused its death.

“There used to be illegal [fishing activities] – such as using electronic shocks – and pollution of the river in the dolphin preservation area, but since we prohibited these things, they seem to have stopped,” he said.

Horm Chandet the manager of the Mekong Flooded Forest (MFF) landscape based in Kratie and Stung Treng provinces, said the dead dolphin was transferred to the WWF office in Kratie for further analysis.

“We have preserved the dolphin’s body in order to search for the cause of death,” he said.

In the first three months of this year, two dolphins – an adult and a calf – were found floating dead on the river, while five dolphins have been born in the same period.