(LI TIECHENG)

Fishing vessels are stuck in the ice at a port in Jinzhou City, northeast China's Liaoning Province, on January 18.

The worst sea icing in 30 years hit China's eastern coast this year, with 30,000 square km or about 40 percent of the Bohai Sea's surface already frozen, the State Oceanic Administration said.

The Bohai Sea is China's only inland sea, with a coastline of nearly 3,800 km.

As the vast ice cap blocks shipping services in and between coastal Liaoning, Hebei and Shandong provinces and Tianjin Municipality, local governments have activated emergency relief measures to help stranded island residents.