Crown of Thorns Starfish Control

Coral bleaching at Lizard Island

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#COTS

The Pacific crown-of-thorns starfish (COTS; Acanthaster cf. solaris) is a coral eating starfish that is native to the Great Barrier Reef. A single adult COTS can consume approximately 10m2 of coral per year, and under normal conditions, the level of coral predation by COTS can be sustained with no apparent long-term reef degradation. However, when COTS population numbers increase out of the normal range, they can reach densities where the COTS eat coral tissue at a rate faster than the coral on the reef can grow. This population increase is known as a COTS outbreak, with the Reef currently experiencing its fourth major recorded outbreak.

Historically, management of COTS has been largely focused on surveillance to detect outbreaks and on culling adult starfish during an outbreak phase. The current method is time-consuming and relies on divers manually injecting each starfish with a custom-designed liquid that is toxic to COTS but harmless to the marine environment. With numbers in the millions during an outbreak, this control method does not, aim to completely contain the outbreak or eradicate COTS. Instead it focuses on protecting a small number of reefs, identified as high priority based on their high economic (tourism) or ecological value.

The GBRF RTP COTS Control Component focuses on efforts to control COTS with the goal to expand and improve COTS management to reduce coral mortality from secondary outbreaks at high ecological and economic value coral reefs in the short-term with a view to achieving better prevention and/or suppression and containment of primary outbreaks in the near to medium-term. 

#Focus areas

Support existing in-water COTS control and drive towards improved efficiency

Lead a step change in surveillance for early COTS detection and early intervention

Explore alternative control methods to address COTS management at a broad scale in the future

#COTS Control Innovation Program

​Recognising that manual control of COTS during outbreaks is not, on its own, an ideal long-term solution, new efforts were launched in 2016 to develop an Integrated Pest Management approach for COTS (as part of the National Environmental Science Program, NESP), led by CSIRO and involving numerous partners. This approach relies on understanding COTS distribution, movement and population dynamics, targeting critical locations and exploring new and more effective control methods. This involves both improving the efficiency and effectiveness of the current methods while also focusing efforts on the pre-conditioning and initiation phases.

Research and innovation are major elements of the COTS Integrated Pest Management (IPM) strategy as it provides a pathway for continuous improvement and adaptive management. Linking back to that overarching strategy, the Reef Trust Partnership has established the COTS Control Innovation Program (CCIP), managed as a consortium, to create a step change and accelerate the development of innovative control and surveillance methods while continuing to improve the efficacy and efficiency of current methods.

The proposed program is based on two independent phases:  

  1. A CCIP Feasibility and Design Phase (12 months), focused on assessing the feasibility (technical, social and regulatory) and modelling the benefit (impact) at scale of a broad range of possible improvements and interventions. Applying a transparent and consistent scientific framework, this phase will lead to recommendations on priority areas that should be further investigated and developed;  
  2. A targeted CCIP (36 months), giving effect to the recommendations of the feasibility and design phase, and identifying pathways for implementation and integration into the COTS control program.   

#Long-term funding strategy for COTS control

Effective action on COTS predation will be one of the strongest levers to protect coral cover in the coming decades, therefore a long-term approach to sustained funding is imperative.  

A funding strategy that presents a comprehensive business case and real options to support planning and policy development for long-term funding of COTS management will be delivered.