Coral-eating starfish could destroy Pratas Islands ecosystem in 2 years: Scholar

Taipei, May 8 (CNA) A scholar warned Thursday that a coral-eating starfish could wipe out the reef around Pratas Islands National Park -- Taiwan's only marine national park -- within two years if its population isn't controlled.

At a press conference in Taipei, Jeng Ming-shiou (鄭明修), executive officer of the Biodiversity Research Center at Academia Sinica, identified the crown-of-thorns starfish (COTS) as the main cause of hard coral decline in the region.

COTS, the common name for Acanthaster planci, is a heavily spined starfish that feeds on stony corals. It has devastated coral ecosystems in Australia, Guam and other regions around the world, according to a statement by the Taiwanese Coral Reef Society.

Jeng based his two-year projection on a 1967 COTS outbreak in Guam, where the starfish consumed all coral within a 38-kilometer perimeter in just 2.5 years.

Jeng said a similar outbreak is unfolding around the Pratas Islands, where the COTS invasion began in 2019. He noted that the average size of COTS has doubled from 15-20 cm to about 40 cm, with some reaching up to 60 cm.

The COTS are spreading along the outer ring of the islands at a rate of about 1 kilometer per month. If their reproduction isn't curbed, they could consume all coral along the islands' 47-km perimeter within two years, Jeng warned.

Citing recent data from his volunteer team, Jeng said 33,748 COTS were removed from a 1.6-hectare area on the park's southern side in March and April 2025, surpassing the team's projection of 29,200.

He added that many of the creatures likely remain hidden in waters deeper than 30 meters, making them difficult for ordinary divers to locate.

Jeng, who has conducted underwater surveys for five decades, said the current infestation has overwhelmed civil groups and national park staff, with many volunteers experiencing muscle soreness and related injuries after taking turns on an eight-day COTS-hunting mission.

A single adult COTS measuring 40 cm can produce around 300 million eggs per year, mostly in June and July, he said.

Although the Taiwanese Coral Reef Society recruited 141 volunteers in 2024, weather conditions, including typhoons and ocean currents, limit coral-clearing efforts to roughly 100 days a year.

Jeng said a cross-division task force formed by the government could help facilitate operations.

Noting that corals shelter juvenile fish and shrimp and support many types of seafood, Jeng called them the "rainforest of the ocean" and likened the ongoing destruction at the Pratas Islands to a "conflagration" that demands urgent attention.

"If you are interested in the marine ecosystem, please join us," he said. "The next two months are crucial."