Conservation activists are calling for a more concerted effort to protect the habitat of Irrawaddy dolphins, or pesut, in Mahakam River in East Kalimantan after two of the protected species were found dead, thought to be as a result of widespread environmental problems.

Save Mahakam Pesut Community activist Innal Rahman said the Mahakam pesut was a protected species as it was critically endangered. The population of Mahakam pesut now numbers only 87 individual animals, down from 96 recorded last year.

The first dolphin was found dead in Kutai Kartanegara regency on July 3. It was suspected that the female dolphin died four days before it was found by local residents traveling on the river.

“We saw it stranded near a coal stockpile of coal company PT Morris,” said Rahman, who spotted the dolphin at the location. At 233 centimeters in length and a body circumference of 128 cm, it is believed the dolphin was fully mature.

On July 7 a pregnant dolphin was found dead on nearby Mangempang Beach. Muara Badak resident, Saidah, reported the beached dolphin to the Navy.

“We later removed it to our post for a further examination,” said the post’s commander Second Lieut. Karel Setiawan. Several old wounds, possibly caused by the propellers of boats using the Pangempang River, one of the Mahakam River’s tributaries, were found on the dolphin’s body.

There are human settlements, coal stockpiles and oil palm plantations built along the Mahakam River and its tributaries. “Dolphins are a sensitive species. Noise caused by boat engines cause them to lose direction, disrupting their efforts in foraging for food,” said Danielle Kreb, a researcher at the Rare Aquatic Species Indonesia Conservation Foundation in Samarinda.