Crown of Thorns Invasion - What to do ??

[Tassie_Rohan]

There has been a lot of work done on COT's in Australia over the past 30 years. This was based on the fear that population explosions would lead to the destruction of the great barrier reef. This has turned out not to be the case.

The most effective way to kill them was to injecting a copper solution using a long spear. However most attempts to control the population were ineffective: as the report above mentions on one small reef they removed 44000 COT's but the reef was still overrun.

Population explosions are now seen as a natural event, which take a few years to run their course. Unfortunately it may take 5-15 years for the coral to fully recover.

It’s hard to just stand by - but for a control method to be effective it sounds like you will have to choose a small area and patrol it regularly. Email some of the researchers at AIMS working on this problem and I'm sure they will be able give you a few tips.

Maybe those trigger fish do have a use after all.

Cheers,
Rohan.

 

[TheFoggyMask]

The only natural predator of COTs in Hawaii is the Triton's Trumpet, which has been drastically overcollected for their shells. I've been told to feel free to take a three prong to any COTs I find and bring them back to the beach to dry up. I wouldn't recommend cutting them up since you could either get stung, or end up increasing their population by spreading little bits of them around to regenerate. Best bet is to dry 'em out on shore.

Its also going to take a lot longer than 5-15 years for a reef to regenerate after being eaten by a swarm of COTs. In australia removal of natural predators and even the excess nutrients from runoff might result in a higher survival rate of baby COTs. Population explosions WERE natural, occurring after a set number of years, where they would move out in a circular pattern from one or two areas and eat the reef. Now they're out of control and nobody is going to bust your balls for killing as many as you can.

 

[Eileentk]

Not sure if this was effective or not but the local dive masters in the Sea of Cortez would turn the COT over and pin it down with a few large rocks so that it could not feed. They believed that the COT would starve in that position and/or be eaten. Since this was a couple of years ago, I'd be interested to know if this method is still being used and if it was deemed effective.

 

[Bowmouth]

Not sure if this was effective or not but the local dive masters in the Sea of Cortez would turn the COT over and pin it down with a few large rocks so that it could not feed. They believed that the COT would starve in that position and/or be eaten. Since this was a couple of years ago, I'd be interested to know if this method is still being used and if it was deemed effective.

Most coral reefs in Asia do not have lots of rocks laying around. Mostly anything with a hard structure will have coral, sponges, algae or hydroids growing on it. Moving rocks and/or coral heads to pin COTS with may be actually ending up becoming very destructive for the reef itself. Also please think about all the tiny invertabrates that live and find protection under rocks and coral heads.

COTS should be removed from the reef carefully and brought back to shore where they can be buried or just left to rot. However, nature is best at finding its own solutions to its problems and humans often do more damage than good while "trying to give mother nature a helping hand".
Ten to fifteen years for regeneration seems a long time for a human but is nothing for our natural world.