Farmers work at a vegetable field on Yongxing Island.

Plenty of fish

The Sansha Deepwater Farming Plan, released in February, states that by 2015 the city aims to have fish kept in about 3,000 netted cages.

Nansha Islands and the surrounding 820,000 sq km of water are a prime fishery resource, with the potential for producing an estimated 1.8 million tons of more than 20 species of fish a year, according to the Hainan Provincial Fishery Research Institute.

In the past year, fisheries in Hainan have received government approval to build deep-sea fish farms in islets and reefs in the Xisha and Nansha island groups.

However, Ji Guobiao, a researcher with the State Oceanic Administration's Third Institute of Oceanography, urged authorities to carry out a comprehensive investigation into resources in the South China Sea to better develop the industry.

"The Sansha bio-system is very simple compared with the Chinese mainland and needs special care," he said, and warned: "Once the balance is broken, recovery may be impossible".

Authorities say they are working on a special coral reef preservation zone to protect the diverse eco-system off Zhaoshu Island, which could be finished this year.

In December, the city launched a tree-planting program on four islets and reefs to curb soil erosion, with 500 trees planted on Yagong Islet in Xisha Islands in March.

"We're planning the second round of tree planting now," mayor Xiao said. "Sansha will become greener."

Contact the writers at wangqian@chinadaily.com.cn and huangyiming@chinadaily.com.cn