The Torres Strait is home to the most stable and robust population of dugong on the planet.

Key points: Up to 25,000 dugong roam beds of shallow seagrass in Torres Strait

Up to 25,000 dugong roam beds of shallow seagrass in Torres Strait Torres Strait Treaty allows locals from PNG and Australia to hunt dugong for personal needs

Torres Strait Treaty allows locals from PNG and Australia to hunt dugong for personal needs ACIC investigation reveals PNG fishermen may be illegally poaching dugong in Australian waters

Up to 25,000 of these mild-mannered and vulnerable creatures roam beds of shallow seagrass in Australia's north and in the coastal waters off Papua New Guinea's south coast.

While limitations have been placed on the hunting of dugongs, a recent report has sparked concern that PNG fisherman may be illegally poaching dugong in Australia's northern waters.

An internal Australian Crime Intelligence Commission (ACIC) document — obtained under freedom of information by The Cairns Post newspaper — has revealed investigators thought the activities of PNG fishermen may be contributing to a decline in dugong numbers.

ACIC's Environmental Crime Team spent two years, at a cost of $2 million, investigating the illegal trade in turtle and dugong meat.

While the results of their probe were handed to Australia's Department of Environment, they have never been publicly released.

The hunting of dugongs in Australia's waters for commercial trade could be in breach of a treaty designed to protect marine life in the region.

Dugong hunters with a captured dugong in Torres Strait. ( Supplied: Colin Riddell )

The Torres Strait Treaty allows for locals to move freely between PNG and Australia and also encompasses the right to hunt dugong, sea turtle and other protected or endangered species for personal, domestic or non-commercial communal needs.

Torres Strait Mayor Fred Gela said because there is a lack of enforcement of that treaty in PNG to protect the dugong population, villagers from the Western Province may be putting them at risk.

"[Families] are using unconventional methods to capture dugong — they're being captured in large numbers," Mr Gela says.

"Even though it's actually illegal to sell in the streets and market, it's definitely happening."

Australian Government plays down allegations

When the Australian Crime Intelligence Commission's Environmental Crime Team was established three years ago, it launched a detailed investigation into the extent of an illegal trade in turtle and dugong meat, producing a total of 15 intelligence reports on the issue.

The findings were passed on to Australia's Department of the Environment — which chose not to disclose the details to the public.

Australian officials have maintained the poaching of dugong and turtles is only minimal. ( supplied: Great Barrier Reef Marine Park Authority )

It was referred to in Parliament in September by Australia's Minister for the Pacific and International Development Concetta Fierravanti-Wells, who played down allegations of illegal hunting.

"The investigation subsequently found that the poaching and sale of meat was almost certainly minimal and usually opportunistic," Ms Fierravanti-Wells said.

"There was no substantive evidence to suggest an organised commercial trade existed in Queensland or the Torres Strait."

However, the internal document obtained by The Cairns Post said the full extent of poaching in the region was not known.

The Australian Fishing and Management Authority denies there is a serious problem with over-hunting in the Torres Strait.

General manager of operations Peter Venslovas told the ABC that extensive monitoring has not unveiled any widespread poaching on either side, and praised PNG authorities who he said work closely with AFMA to protect marine wildlife.

"It happens sometimes, but certainly not often," he said.

"We have a fairly extensive surveillance program in the Torres Strait which entails aerial surveillance; we've got planes up in the air every day."

Diplomatic solution needed, Mayor says

The claims that illegal dugong poaching is not widespread were challenged by environmental activist Colin Riddell, who is critical of the ACIC report.

He said PNG fishermen have also been caught taking large numbers of turtles — beyond the terms of the Treaty of Torres Strait.

Environmental officials in PNG say Indonesian poachers pose an even bigger threat. ( Supplied: Ahmed Skawky )

"There were 100 turtles on their backs one night and we had a ranger ring up in tears who rang up our local member, Warren Entsch, and he was distraught that the Papuans were coming over to pick up those turtles," Mr Riddell said.

The head of marine ecosystems for PNG's Environmental Protection Authority, Vagi Rai, told the ABC his Government had been working hard to stamp out the practice of commercial dugong hunting since launching a campaign in 2013.

"Within three years we managed to zero down on a no tolerance catch of dugongs and sale of dugongs at any markets," he said.

Mr Rai said the issue is being exacerbated by Indonesian hunters operating in the region.

"Indonesia is coming across and they're harvesting our dugongs, the dugong tusk has a market and it's putting extra pressure on us," he said.

Mr Gela said a diplomatic solution needed to be considered.

"I think it goes beyond just coming in with a heavy hand," he said.

"Between the Australian Government and the PNG Government, a conversation needs to happen."

In a statement, Australia's Ministry for the Environment said it has no evidence to dispute the findings of the ACIC investigation, and has no reason to pursue a diplomatic resolution to concerns over dugong poaching.