Crown-of-Thorns Cull: UPDATE

Crown-of-Thorns Cull: UPDATE

UPDATE: Divers kill 47,000 crown-of-thorns starfish in southern Great Barrier Reef record-breaking mission

Posted on 22.01.2018

The volunteer divers returned, tired but jubilant, after a nine-day culling mission on the Swains Reef.


Volunteer divers have killed almost 47,000 crown-of-thorns starfish on the southern Great Barrier Reef in just seven days, breaking a record in the process.

Thousands of the starfish were discovered only months ago eating their way through parts of Swains Reef, which lies 250 kilometres off the central Queensland coast.

Gladstone charter operator Bruce Stobo led the group of 25 volunteer divers on the nine-day mission.

“They tell me, unofficially, that it’s the most amount of starfish that [have] been killed in a single trip in that time,” said Mr Stobo, who donated his catamaran to the mission.

Similar missions have culled up to 30,000 crown-of-thorns starfish.

Queensland Parks and Wildlife detected the infestation during a survey in November last year, but this did not prepare the divers for what they saw.

Original Story

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.

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.

Crown-of-thorns Facts

  • 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
  • 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
  • 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

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.”

ABC News




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