Local fishermen who found the carcass near Baan Kho En reported their discovery to the Phuket Marine Biological Centre (PMBC) at Cape Panwa at about 10:50am.
Fishermen first noticed the dugong and quickly secured the carcass by tying a rope to its tail to prevent it from drifting out to sea.
The remains were then brought to shore, where officers from Tha Chat Chai Police were also notified. The discovery attracted a crowd of curious onlookers from the local community.
Upon initial inspection, marine officials identified the animal as a fully grown male dugong, weighing over 150kg and measuring about two metres in length.
No visible wounds were found on the carcass, but an autopsy will be conducted to determine the exact cause of death, the PMBC reported.
Authorities speculate that the dugong may have wandered from Phang Nga Bay before ending up on Phuket’s east coast.
The carcass will be further examined by the the Sireetarn Marine Endangered Animals Rescue Centre at the PMBC to gain more insight into the incident.
Dugongs, gentle marine mammals often referred to as "sea cows," are a protected species in Thailand, and after spate of deaths in Thai waters throughout the year, the discovery of their deaths is often treated with urgency.