A crown-of-thorns starfish or taramea underwater. Photo: Kōrero O Te `Ōrau
More than 6500 coral eating crown-of-thorns starfish have been removed from Cook Islands' reefs since 2020 when the latest outbreak was first detected.
The starfish, called taramea in Cook Islands Māori, have decimated the country's reefs in the past with previous recorded outbreaks in the 1970s and in the mid-1990s.
Marine biologist Teina Rongo is leading the removal of the starfish and named it Operation Taramea.
"Both outbreaks took around seven years to completely decimate the corals on the reefs on Rarotonga," Dr Rongo said.
"The consequences of a taramea outbreak does not only kill the reefs, but it leads to the loss of resources and the loss of revenue that people could make from selling fish. So it extends beyond just the reef dying."
Dr Teina Rongo who leads Operation Taramea says past crown-of-thorns outbreaks decimated Cook Islands reefs. Photo: Cook Islands News
Dr Rongo said an outbreak also increases the risk of people getting fish poisoning or ciguatera that can lead to death in severe cases. It's caused by eating reef fish that have been contaminated by certain toxins.
"When the reef is degraded or when the reef is killed, it provides a place for algae to grow and the microscopic organisms that produce the toxin lives on this seaweed.
"So it just provides more places for these microscopic seaweed that produced the toxins to live, so having a dead reef increases the probability of poisoning happening."
Taramea are native to Rarotonga but normally reside in low numbers.
Dr Rongo said normally the starfish maintain biodiversity by keeping more dominant coral at bay so other coral can grow.
He said large outbreak numbers are largely a result of land-based development.
"A lot of the nutrients from leaky septic tanks and agriculture development are loading nutrients into the marine environment.
"Crown-of-thorns at the early stage of their lifecycle feed on plants, and these plants are fed by the nutrients that come off the land. If you have a lot of nutrients you increase the chance of baby taramea surviving."
Teina Rongo is also the chairperson for Kōrero O Te `Ōrau, an environment charity which works with young Cook Islanders.
He said Operation Taramea has made young people passionate about the ocean.
"A lot of these kids that have come through our programme all want to be marine biologists, or at least environmental scientists, which is really good for us.
"We need more of our young people to go into these areas of marine, particularly the technical areas."
A diver brings to the surface crown-of-thorns starfish removed from the reef. Photo: Kōrero O Te `Ōrau
