Fishery officials in the Kazak Autonomous Prefecture of Ili have tightened supervision of a border river where fishing is banned from Feb. 15 to May 31 each year.

The patrols are also handing out leaflets to keep local fishermen informed of the ban and the importance of biodiversity.

"Spring is crucial for the fish as they spawn at this time," said Yong Weidong, Ili's fishery chief. "Fishing of all aquatic products are prohibited on the Chinese side of the river during the ban. Trading of aquatic products caught during the ban are also prohibited."

The 100-day fishing ban was endorsed by Xinjiang's legislature in 2004.

Ili River runs more than 1,200 km from China's Xinjiang to southeastern Kazakhstan, where it flows into Lake Balkhash.

About 32 species of fish live in the 420-km Chinese section of the river.