“Star Wars” is unfolding on the Great Barrier Reef as operators rapidly respond to a new crown-of-thorns starfish outbreak off Cairns. The Reef Authority is deploying Crown-of-thorns starfish (COTS) Control Program vessels and dive teams to suppress an emerging outbreak of the coral-eating starfish on high-value reefs between Cairns and Lizard Island.
Crown-of-thorns starfish outbreaks can devastate entire sections of coral reef, with one adult starfish consuming a dinner plate-sized piece of coral every day or two. “COTS control is the most targetable and effective way humans can protect the Reef,” Reef Authority Chief Scientist Dr. Roger Beeden said. “We can’t prevent the cumulative impacts of cyclones, floods, and coral bleaching,” he added. “But we can suppress COTS outbreaks and protect coral from starfish predation across entire reefs and regions.”
Intensifying Efforts to Protect the Reef
Funded by the Australian Government, the COTS Control Program currently deploys six vessels, each with teams of six to ten divers who cull the starfish using a lethal single-shot injection of household vinegar or ox bile salt solution. Dr. Beeden noted that adult COTS densities are expected to increase substantially on reefs offshore Cairns as this fifth recorded outbreak cycle emerges across the northern Great Barrier Reef (GBR), with more than a ten-fold increase in COTS densities possible on some reefs.
“It’s our version of ‘Star Wars’, and we are fighting these starfish outbreaks on multiple fronts,” the Chief Scientist commented. “We have repositioned some of our COTS Control Program fleet to proactively suppress the emerging outbreak in the North, while maintaining some control effort in the central and southern GBR to secure longer-term coral protection outcomes—protecting the Reef’s ecological integrity and outstanding universal value.”
The Economic and Ecological Stakes
Tourism linked to the Reef contributes about $9 billion annually, highlighting the importance of protecting high-value reefs. The northern region is both ecologically and economically critical, including the Cairns to Cooktown area, identified as the “initiation area” for four previous large-scale outbreak waves across the Reef. Since 2012, the COTS control program has protected over 830,000 hectares of coral reef habitat spanning several hundred reefs from the tip of Cape York to Bundaberg—at a cost of about $175 a hectare.
“It augments our Marine Park zoning plan where reduced pressure on fishing of natural predators of juvenile COTS like emperor, snapper and coral trout is a proven success,” Dr. Beeden said. “It isn’t currently feasible to deliver coral restoration at the scale of the COTS control program as it would cost hundreds of billions of dollars with current technologies.”
Collaboration and Community Involvement
Reef and Rainforest Research Centre (RRRC) managing director Sheridan Morris oversees a contract with two dedicated COTS Control Program vessels operating in the Cairns region. She said the COTS crews and tourism operators were actively working to cull starfish and protect the high-value tourism reefs off Cairns, visited by more than one million tourists every year. “COTS control is the biggest response we have to keep our reefs resilient and healthy,” Ms. Morris said.
The Reef Authority, through the Tourism Reef Protection Initiative (TRPI), funds tourism operators to conduct monitoring and culling of COTS on their sites, feeding data to the Reef Authority in a unified, science-led approach to managing outbreaks. Gareth Phillips, of the Association of Marine Park Tourism Operators (AMPTO), stated that the Reef tourism industry has long been at the forefront of crown-of-thorns starfish control.
“Protecting the Reef is not just an environmental priority—it is fundamental to the future of Reef communities, tourism jobs, and Australia’s most iconic natural asset,” the AMPTO chief executive said. “Long before large-scale programs were established, tourism operators were on the water reporting outbreaks, supporting early intervention efforts, and working alongside scientists and the Reef Authority to protect the health of the Great Barrier Reef.”
Understanding the Crown-of-Thorns Starfish
Crown-of-thorns starfish (COTS) are a native species on the Great Barrier Reef, instantly recognizable by their long, venomous spines. They are the world’s second-largest starfish, capable of growing to almost one meter in diameter, and with spines coated in a toxic slime. Natural predators include fish species such as emperor, snapper, coral trout, tuskfish, and Maori wrasse, triggerfish, pufferfish, and the giant triton snail.
- A single mature female can release up to 200 million eggs a year.
- Causes of outbreaks are not entirely known but could be contributed to by:
- Excess nutrients from run-off and natural upwelling
- Availability of live coral to eat
- Ocean currents that spread larvae across the Reef
- Removal of natural predators
The current COTS control program is a strong example of what can be achieved when industry, science, and government work together to protect one of the world’s most treasured natural wonders. As efforts continue, the collaboration between various stakeholders remains crucial in ensuring the long-term health and sustainability of the Great Barrier Reef.
