A vulnerable Irrawaddy dolphin was found dead in Kratie’s Sambor district on Tuesday after being caught in fishermen’s illegal gill nets, authorities and environmental watchdogs said.

‘‘I think this dolphin may have been dead for three or four days – its body was swollen and rotten, and its tail was tangled in nets,’’ said Seang Sokhim, a guard for the Koh Pdav natural dolphin pool.

Emma Fry, a communication assistant with the World Wildlife Fund, said the female dolphin was 183 centimetres long and weighed 80 kilograms.

This is the first time that locals saw a dolphin succumb to illegal fishing equipment, according to Sokhim.

However, communities in Stung Treng and Kratie have been aware of gill nets’ threat to dolphin populations for a long time, according to experts from WWF and environmental group MLUP Baitong.

Dolphins entangled in the nets usually die because they can’t come up for air, they said

WWF country director Chhith Sam Ath said yesterday last year’s survey found only 80 dolphins in Kratie and Stung Treng. Nine dolphins died over the course of 2015. So far, two have died this year.