Household vinegar could be a key ingredient in the fight against crown of thorns starfish on the Great Barrier Reef.

Crown of thorns starfish (COTS) is a pest which eats coral tissues, posing a huge threat to the reef.

Australian Institute of Marine Science research showed coral cover on surveyed reefs had declined by about 50 per cent over the past 30 years, with COTS responsible for almost half of that decline.

James Cook University scientist Lisa Boström-Einarsson searched for an eradication method for COTS that was cheap, easily available and safe for everything other than the starfish themselves.

Her method involved injecting the COTS with 20 millilitres of household vinegar.

The trial saw a 100 per cent kill rate within 48 hours of injection.

"I tried alcohol [first] and that did not work very well and then I heard some rumours that some people had used vinegar but had not had very good results," Ms Boström-Einarsson said.

"So I refined the methods a little bit and then it turned out to work really well."

Ms Boström-Einarsson said the starfish were mostly water inside and could not tolerate the acidity of the vinegar.

"The acid basically just melts their insides," she said.

"It is quite dramatic the way they go and within 24 hours there is basically just slime left — it is not pretty."

A crown of thorns starfish clings to a piece of coral.. ( Supplied: Lisa Boström-Einarsson )

Cheaper, easier method to tackling pest

The current eradication practice is to inject the COTS with ox bile which is much harder to come by, more expensive and could cause quarantine issues as it is an animal byproduct.

Ms Boström-Einarsson has worked on this research for a year, and has tested her method around Lizard Island in far north Queensland and in Papua New Guinea.

She said the next step was large scale field testing to ensure process was safe for other marine life.

Researchers have discovered crown of thorns starfish can not cope with the acidity of vinegar after it is injected in the pest that is threatening the Great Barrier Reef. ( Supplied: Lisa Boström-Einarsson )

"I'm working with the Great Barrier Reef Marine Park Authority on doing the final field tests ... so they can endorse it as an approved method," Ms Boström-Einarsson said.

"Everyone is very positive because it is a simple method — it just needs one injection and it is safe for the divers to do it and it works really well so there's been a lot of interest around the world."

Despite this, Ms Boström-Einarsson said this method would not be the saviour of the Great Barrier Reef, but could save individual reefs in the meantime.

"Ideally we would stop the [COTS] outbreaks from happening or we would control the outbreaks at a population level," she said.

"But at the moment we do not have the tools to do that and we do not have the knowledge to know what causes the outbreaks.

"What we can do is [make] sustained efforts at local reefs and protect them and for that this method will be really effective."