Authorities are disgusted by the discovery of two rare dolphins found dead, tied to mangroves, and weighed down by a slab of concrete in north Queensland.

A local recreational fisherman found the rare snubfin dolphins near the mouth of Two Mile Creek, north of Townsville.

Authorities say the dolphins were hand-tied to the mangroves and they are appealing for leads to find those responsible.

Richard Leck from the World Wildlife Fund says he is incensed.

"The killing and concealing of these two dolphins is totally reprehensible and completely out of line with what the community expects what happens within the Great Barrier Reef World Heritage area," he said.

Great Barrier Reef Marine Park Authority officer Mick Bishop says it is a disturbing find.

"Certainly, somebody's been involved in that because of the very nature of it. In some cases, when you find dolphins, there's possibilities of disease or starvation or whatever," he said.

Mr Bishop says it could be related to illegal fishers who may have tried to conceal the accidental killings of the dolphins.

"The most likely of the explanation is that they would have been caught in a fishing net," he said.

"There was no evidence of propeller strike or anything like that and generally a boat strike, most people don't even know they've done it.

"And so most likely, it would be a fishing net to have caught two dolphins. In those cases it could have occurred quite legally and the net could have been set legally, but there's an obligation on operators to report these deaths."

Nearly 12 months ago a commercial fisherman spotted four dugongs tied up in a similar way in Bowling Green Bay, off the coast of Townsville.

Mr Leck says he would like to see the perpetrators of this latest case brought to justice so it does not happen again.

"Obviously the people involved know what they've done but it's unlikely that this activity happens without other people being aware," he said.

"Now's not the time for fishers to be protecting their mates. Now's the time for fishers to be protecting their species and we call on people who have some knowledge of this to come forward."

Legal fishers do not face fines for reporting the accidental netting of a marine creature like a dolphins, dugongs or turtles.

But Mr Bishop says unregistered trawlers in that region face severe prosecution if they snag and kill protected wildlife.

"There's several different [pieces of] legislation; there's state, federal and marine park legislation. But, for example, under state legislation the maximum fine could be $330,000 or two years in prison," he said.

Mr Leck says he wants the snubfin officially listed as a threatened species as there are only about 1,000 left in the wild.

"The snubfin has recently been declared in the last 10 years as a new species of dolphin," he said.

"It was originally confused with another inshore dolphin but this is Australia's very own inshore dolphin. It's very rare and little is known about it."

Authorities in central Queensland are also puzzled by the deaths of two adult dolphins which washed ashore in the past fortnight.