In the past four years, Li and his colleagues have bred about 2,000 turtles and released more than 1,000 into the sea.
The turtles used to be abundant in Xisha, but due to years of excessive hunting, their numbers dropped drastically.
In 1989, China listed the species under State protection and has since improved measures to crack down on the capture and trade of sea turtles and their eggs.
After Sansha was established in 2012, the city government issued a strict ban on turtle poaching in all areas under its jurisdiction, including Xisha, while educating local fishermen on the protection of the rare species.
Since then, poaching has plummeted, and local fishermen voluntarily take up the job of turtle protection.
In 2015, the community of Xisha's Beidao Island also set up a sea turtle preservation station. Huang Hongbo and his two sons are among the 15 fishermen who have patrolled the island during the past two years to protect the turtles.
"If we find turtle nests on the beach, we set up wooden signs to alert local fishermen to be careful and not harm them," said Huang, 65, head of the sea turtle preservation station. "We also patrol along the beach to prevent poachers from stealing turtle eggs."
Huang said turtles often crawl up onto the beach at night with the tide.
"Female turtles choose soft sand, dig holes with their flippers and then lay eggs inside. Each egg is the size of a ping-pong ball," Huang said.
In 2016, Huang and his colleagues found more than 160 turtle nests on the island.
"The sea turtles have fixed hatching places. They will lay eggs in the place where they were incubated," he said. "It's great to see increasing numbers of turtles coming to our island to breed."
