6000 starfish removed from Cook Islands

June 26, 2023

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More than 6,500 crown-of-thorns starfish have been removed from the reefs in the Cook Islands.

These starfish, known as taramea in Cook Islands Māori, have caused significant damage to the country’s reefs in previous outbreaks, such as those recorded in the 1970s and mid-1990s.

Marine biologist Dr. Teina Rongo is leading the removal efforts, known as Operation Taramea. Previous outbreaks took approximately seven years to completely devastate the coral reefs on Rarotonga, the largest island in the Cook Islands. The consequences of a taramea outbreak extend beyond the reef dying, as it also leads to the loss of resources and revenue that could be generated from selling fish.

Moreover, outbreaks increase the risk of ciguatera, a type of fish poisoning caused by consuming reef fish contaminated with certain toxins. The degradation of the reef creates an environment where algae can grow, and the microscopic organisms producing the toxin thrive on this seaweed. Therefore, a dead reef increases the likelihood of ciguatera poisoning.

Dr. Rongo explained that crown-of-thorns starfish normally play a role in maintaining biodiversity by keeping dominant coral species in check, allowing other coral to grow. The large number of outbreaks is largely attributed to land-based development, with nutrients from leaky septic tanks and agricultural activities entering the marine environment. The starfish larvae feed on plants that are nourished by these nutrients, leading to higher survival rates for the taramea.

Dr. Rongo, who is also the chairperson for the environmental charity Kōrero O Te `Ōrau, noted that Operation Taramea has sparked a passion for the ocean among young people. Many of the program’s participants aspire to become marine biologists or environmental scientists, which is seen as a positive development to address the challenges facing marine ecosystems.

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