Fish poo could hold the answer to tackling the large numbers of crown-of-thorns starfish eating their way through the Great Barrier Reef.

Researchers from the Australian Institute of Marine Science in Townsville have been collecting samples to try and identify fish which eat the native starfish.

Outbreaks of the crown-of-thorns starfish are a major threat to the reef's health, with divers recently culling more than 47,000 starfish at a remote reef.

The Institute's Dr Frederieke Kroon, who is leading the project, said scientists were testing more than 400 poo samples.

"Previously what would have been done was collect the fish, open up the fish to have a look at the contents of the guts to see if any crown-of-thorns starfish remains were in there," she said.

"With the DNA probe we have now, we don't have to be invasive and we don't have to kill the fish."

Promising results

Dr Kroon said early results indicated the large puffer fish and some Emperor species may be predators of the starfish.

"We'll be targeting those again in July when we go out to the field to look at fish species that may eat the larger crown-of-thorns starfish," she said.

She said fish identified as predators of the crown-of-thorns starfish could receive greater protections.

"So on the ground, what that may mean is for fish species we've found eat crown-of-thorns starfish, make sure they're well protected and we have good numbers of those species around in areas where crown-of-thorns starfish outbreaks first start," she said.

The study is expected to be completed later next year.