SW Pacific, Indonesia, Raja Ampat Islands: Outbreak of Crown of Thorns (CoTs) Starfish

There is a currently an outbreak of the Crown of Thorns (CoTs) starfish (Acanthaster Planci) in the Raja Ampat islands​, eastern Indonesia. CoTs eat coral flesh, leaving a white skeleton behind. The CoT has been devastating on the Great Barrier Reef in Australia. Here is how the cruising community can help the people of Raja Ampat before it’s too late.

Published 5 years ago, updated 4 years ago

Crown of Thorns or CoTs (Acanthaster Planci)


Information on the spread of this sea star – Crown of Thorns or CoTs ( Acanthaster Planci)

The pristine reefs of the Raja Ampat islands are now facing a new threat.

Australia, Tahiti, parts of Japan and many other places have suffered severe coral depletion from this predator of corals. The loss of corals can lead to completely barren areas where once the corals thrived.

Healthy coral means a biodiverse habitat, community food security and a major attraction for tourism.

How you can Help

Assistance from cruising yachts in Indonesia (and indeed all the SW Pacific) to inform when and where you spot CoTs in populations of more than 1-2 per dive or snorkelling traverse along a reef, would greatly assist the planning for control measures.

Infestations of 5-10 CoTs observed in any one traverse represents an “outbreak” that can lead within a short time to a large barren area of reef.

Also remember that the CoTs are most active in darkness, so daytime observations will tend to underestimate the true numbers.

All outbreaks in the SW Pacific area are of interest.


Please be aware that the CoT sea star has a very potent toxin in its spines. A puncture wound is a very painful experience.

How to Report

Please advise any sightings via email to:

Warwick  Alliston-

E-mail: [email protected]

or WApp: +62811485371

Reports from cruisers will greatly contribute to the knowledge of the spread of CoTs. Government approval to conduct any form of culling is still pending, but information on the locations where CoTs are observed is vital as the start of the process.

Informative Video about the Crown of Thorns Starfish

Australia’s Crown of Thorns Control Programme

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