Thousands of crown-of-thorns starfish found eating their way through the southern Great Barrier Reef only months ago are being targeted in a major culling exercise over the next week.

Crown-of-thorns facts: The crown-of-thorns starfish (Acanthaster planci) is native to coral reefs in the Indo-Pacific region

The crown-of-thorns starfish (Acanthaster planci) is native to coral reefs in the Indo-Pacific region The coral-eating starfish plays an important role on reefs as it feeds on the fastest-growing corals such as plate corals, allowing slower-growing species to form colonies, increasing coral diversity

The coral-eating starfish plays an important role on reefs as it feeds on the fastest-growing corals such as plate corals, allowing slower-growing species to form colonies, increasing coral diversity When numbers are low the coral can recover, however during an outbreak the starfish can destroy up to 95 per cent of the hard coral, totally denuding the reef

When numbers are low the coral can recover, however during an outbreak the starfish can destroy up to 95 per cent of the hard coral, totally denuding the reef Cyclic outbreaks occur about every 17 years

Cyclic outbreaks occur about every 17 years There have been four documented outbreaks on the Great Barrier Reef since the 1960s, with the latest starting in 2010

There have been four documented outbreaks on the Great Barrier Reef since the 1960s, with the latest starting in 2010 They spawn during the warmer months (around October to February), with large females capable of producing up to 65 million eggs over the spawning season

A group of 25 divers are spending nine days on Swains Reef, 250 kilometres off the coast of Gladstone, as part of a collaboration between government agencies, industry and the community to tackle the outbreak.

Project manager for the Crown-of-Thorns Starfish Control Program, Steve Moon, said the aim was to kill 1,000 crown-of-thorns starfish per diver per day.

"In recent months, occupational crown-of-thorns starfish divers have culled as many as 30,000 crown-of-thorns starfish in a single voyage," he said.

"The reported outbreak at the Swains still requires further investigation and the actual cull numbers will be determined by the size of the aggregation, weather, visibility, depth and the experience of the diver."

Authorities have been worried about how to tackle the outbreak, which was discovered eating away at the southern end of Swains Reef when the Queensland Parks and Wildlife carried out a survey in November.

"Swains Reef is a beautiful complex and it would appeal to any crown-of-thorns. This is a lovely smorgasbord and they are probably seizing the opportunity to take advantage of that," Mr Moon said.

Volunteer divers are heading out to the Swains Reef to cull crown-of-thorns starfish found in recent months. ( ABC Capricornia: Inga Stünzner )

Mr Moon said the program was one of the first times there was such a collaboration between different agencies.

The divers — including volunteers from universities, tourist operators and marine parks — will manually inject each crown-of-thorns starfish with bile salts.

"Bile salts have been field tested for many years and are very efficient," said Mr Moon, who runs the project through the Association of Marine Park Tourism Operators.

"It takes one 10 millilitre injection to a starfish to bring about its demise, as opposed to the old system where we'd have to inject the starfish 28 to 32 times using sodium bisulphate.

"Crown-of-thorns starfish are endemic, they've always been there and are very good for the reef in controlled numbers, but when they start eating more than what can recover then we're in trouble."

Sorry, this video has expired Launch of the one-shot injection killing crown-of-thorns in 2014

Mr Moon said the project was about containment rather than eradication and it had been proven that this intervention project worked.

"We've successfully protected all the key tourism sites in key reefs offshore in north Queensland and with extra resources, which we're looking for, we're very confident that we can minimise any outbreaks in the future," he said.

Queensland Parks and Wildlife has taken its own vessel and crew to Swains Reef to conduct surveys, followed by the remaining divers on a vessel donated by Gladstone charter operators Bruce and Louise Stobo.

Mr Stobo's main business is taking divers and tourists on seven-day charters on his 25-metre catamaran to the southern Great Barrier Reef.

"The Great Barrier Reef and certainly the Swains Reef area has given us a lot over the years and it's giving us an opportunity to try and give back, and it also gives access to the other volunteers," he said.

Bruce Stobo has donated his catamaran, the Kanimbla, and his crew for the nine-day expedition. ( ABC Capricornia: Inga Stünzner )

Mr Stobo said the crown-of-thorns infestation was quite widespread at the southern end of the Swains so was happy to volunteer his boat in the off-season.

The volunteers spent their first morning on training, learning how to serve a lethal injection into the starfish.

"It's not just about injecting them anywhere," Mr Stobo said.

"If you do it arm of the starfish they will drop that arm off, if you do it in the middle of their body they will actually excrete it out.

"So they tell me the shoulder of the starfish — and good luck with that — is the spot to inject them."

Mr Stobo said he was interested to see what the final count would be at the end of the trip.

The crew is expected to sail back into Gladstone Harbour on January 26.