Crown of Thorns

A crown of thorns starfish.

The coastal communities of Vanuatu are currently facing an underwater enemy. The Crown-of-Thorns Starfish (Acanthaster planci), a corallivorous starfish, is experiencing outbreaks all over the country. The reefs are probably Vanuatu’s most important resource and incredibly valuable for tourism. Whereas a small number of Crown-of-Thorns is a natural part of the ecosystem, large numbers can eat up to 95% of the surrounding coral. Once damaged by Crown-of-Thorns (COTs) the reef may take years to recover, or may never regain its colours. Certain fish-life which rely on healthy reef systems to survive, also die out or move to greener pastures.

From November to February, when the water is warmer, this starfish aggregates, reproduces, releases millions of eggs and moves quickly from one reef to another, leaving only white scars and devastated coral behind. During the cooler waters of the trade wind season, the COTs don’t tend to aggregate, so it is harder work to find & remove them. However, they must be stopped preferentially before the spawning season, before they release a huge amount of eggs, so as to minimise any secondary outbreak. Reacting on time will prevent the creation of juveniles, which may drift with the current and settle on a neighbouring island.

COTs have few natural predators, including the Triton shell (Pupu sel which is totally banned for fishing under Vanuatu national fisheries regulation. Unfortunately, triton shells have declined significantly due to illegal fishing, making outbreaks even harder to get solved naturally. Leave Tritons in the ocean to help your environment.

The Fisheries Department of Vanuatu is currently setting a program to mitigate the effects of COT outbreaks across the archipelago. We ask the communities not to act alone. The first thing to do is the assessment. The method is easy. Simply snorkel on the coast for half an hour, with two or three friends, and report how many Crown-of-Thorns you saw. Don’t forget to mention the location and the number of divers. If all coastal villages in the various islands could monitor their reefs and report in the information, then we have a good chance of minimising this current plague.

You can contact the Fisheries Department on: 5333340 or 23119 (ask for Jayven). Volunteers and scientists are doing their best to control the outbreaks but it will never be enough unless the people of Vanuatu help us. Let us work together to protect the environment for future generations.

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