National COTS Project 2025

Mauritius’ coral reefs are under increasing threat from one of the most destructive coral predators in the Indo-Pacific: the Crown-of-Thorns Starfish (COTS). In response to recurrent outbreaks, Coral Garden Conservation (CGC) has been awarded a national contract by the Ministry of Agro-Industry, Food Security and Blue Economy – Blue Economy and Fisheries Division to lead the 2025 COTS Control Project across the island.

Understanding COTS and their impact

COTS (Acanthaster spp.) are large, spiny starfish that play a natural ecological role in maintaining coral diversity by feeding on fast-growing corals. However, when their population density exceeds natural thresholds, they cause catastrophic damage to coral reefs, devouring up to 13 square metres of live coral per year per individual and potentially wiping out over 90% of coral cover during severe outbreaks. These marine predators are highly adaptable, transitioning from an early herbivorous phase to a corallivorous stage in their juvenile development. Their biology characterised by high fecundity, fast growth, and dietary flexibility makes them remarkably resilient and difficult to control once outbreaks begin.

Monitoring and thresholds in Mauritius

Mauritius has established a national COTS protocol, developed by the Albion Fisheries Research Centre (AFRC) and the Coral Reef Network (CRN). The protocol defines an outbreak as more than 5 COTS per 45-minute dive or snorkel, triggering immediate response actions. Monitoring is carried out using timed surveys, belt transects, and visual assessments, with targeted eradication using acetic acid (vinegar) injections—a proven and environmentally safe control method. The protocol was successfully implemented during the 2021–2023 COTS Control Project by Reef Conservation.

The 2025 National COTS Project: What CGC is doing?

Under the newly awarded 2025 contract (Ref: MOBE/Q10/2024-25/OAB1), CGC is leading a nationwide response to detect, control, and prevent further COTS outbreaks. Key activities include:

• Conducting scientific assessments to identify outbreak hotspots

• Deploying trained COTS intervention teams to control COTS population using safe injection-based control methods

• Collaborating with hotels, dive centres, boat operators, NGOs, and community stakeholders

• Launching a national COTS reporting platform to enhance real-time surveillance

• Delivering training and awareness programmes to build local capacity and engagement

This project represents a vital component of Mauritius’ broader reef resilience strategy and reflects CGC’s continued leadership in marine ecosystem conservation.

How can you help?

Public involvement is essential. Whether you're a diver, snorkeller, hotel operator, or fisher, you can make a difference:

• Report sightings via the COTS Online Reporting Form

• Email us: projectassistantcgc@gmail.com

• Call us: +230 5764 8502

• Share awareness materials with your community, guests, or visitors

• Join our training sessions.

Timely reporting can prevent small clusters from becoming full-scale outbreaks.

The 2025 National COTS Project is not just about control—it’s about empowerment, education, and ecosystem protection. With your support, we can mitigate COTS outbreaks and strengthen reef resilience for generations to come.

🔗 Visit the National COTS Project Page

📩 Report a sighting: Submit a COTS sighting report

📞 Contact CGC: +230 5764 8502 | projectassistantcgc@gmail.com