The government’s decades-long coral reef regrowth program in the waters near the Spratly Islands (Nansha Islands ) are showing signs of success, Academia Sinica research fellow Jeng Ming-shiou   said on Friday.

The Society for Wildlife and Nature is holding a lecture series on the progress of public environmental initiatives at the Academia Sinica to mark the International Day of Biological Diversity, said Jeng, who is the society’s president.

In 1998, coral bleaching affected large swathes of the Dongsha Atoll National Park area, prompting the government to implement measures that officials hoped would reverse the effects, he said.

Jeng’s 25-year career as a marine biologist has coincided with the policy and his field research suggests that the reefs have rebounded so that about 40 to 60 percent of the park’s lagoon area is covered, he said.

Fish populations are increasing, including the humphead wrasse — also known as the Napoleon fish — a species deemed endangered by the International Union for the Conservation of Nature, while dolphins feeding on schools of fish have been observed for three consecutive years, he said.

While a lone humphead wrasse about 60cm long was sighted in 2016 at a depth of 25m outside the lagoon, four more of them, including fries, have been sighted since, he said.

The return of the fish to the park shows that maritime law enforcement efforts of coast guard personnel and park rangers have deterred illegal fishing, he said.

The development is encouraging for sustainable tourism, as the humphead wrasse is a big attraction for recreational snorkelers, he said.

Overall, the Napoleon fish population remains stagnant in national waters, indicating that the government should step up maritime conservation efforts elsewhere, he said.

In September last year east of the atoll, his research team discovered a vast undersea cave system at a depth of 15m and sighted a 2m-long silvertip shark, he said, adding that the presence of an apex predator shows that the area’s ecological health is improving.

The cave, 10m across at the widest point, has three ingresses and is more beautiful than a well-known large cavern in Palau called the Blue Holes, according to Jeng.