A new study has revealed the number of turtles being killed by rubbish dumped in the ocean is far higher than rangers previously estimated.

The Earthwatch research reveals that more than one third of turtles that die in Moreton Bay have either eaten or been entangled in marine rubbish.

For a long time it has been thought turtles mistakenly consume soft plastic items like plastic bags and cling film because they believe they are jellyfish.

The report provides more evidence that the creatures are selecting soft plastics over other types of rubbish.

Earthwatch researcher Dr Kathy Townsend dissected and examined the guts of more than 120 dead turtles from the eastern areas of Moreton Bay in Queensland.

She says soft plastic items were found more often than hard plastic, and 30 per cent of the dead turtles she examined had ingested rubbish.

"We went out and looked at what we were finding in the guts of the turtle and then compared that to what we were finding on the beaches in which the turtles had washed up," she said.

"Surprisingly what we ended up finding is that the turtles seem to be selecting or targeting soft plastics with the idea that perhaps these animals are targeting that because they look like jellyfish."

Dr Townsend says ingesting rubbish is particularly dangerous for turtles because of their anatomy.

She says swallowing rubbish means turtles become dehydrated and starve to death in a process that can drag out for months.

"Sea turtles, because of their anatomy, cannot vomit, so if it can't go out the back end, it ends up getting stuck," she said.

"This debris then causes the gut to enter a type of paralysis state and all of the debris and organics that are mixed in with that debris just start to decompose.

"The decomposition process causes gas and the animals then become positively buoyant and that's not good if you're a marine animal because that means you can no longer dive to feed, you can't dive to get out of the way of predators or boats and things as well."

The research found that another 6 per cent of turtles had died after becoming entangled in rubbish.

Dr Townsend says earlier estimates by rangers had put the proportion of turtles dying because of marine rubbish at just 2 per cent.

"I'm not saying that we all of a sudden have more debris in the environment than we had previously; I don't think that's the case," she said.

"I think it's just a case of our methodology has changed and ... the full impact is now actually coming to light."

Dr Townsend says being hit by a boat is the top threat to turtles in the area, but she says rubbish in the water comes a close second.

She says half of all marine debris comes from the land while the other half is from the boats and ships, which she says are allowed to dump rubbish in the ocean once they are a certain distance from the coast.

"It is one of those issues where it's everybody's fault. It's just the way that we live and it's all about the debris that we're creating," she said.

"As soon as it's everybody's fault, it becomes nobody's responsibility, and that's really the difficult thing to crack.

"You also have to take responsibility on a personal level for the impetus to start - to be able to fix the problem."