Frozen seas off the coast of China are expected to expand to severe levels in late January, posing threats to offshore oil and gas fields, leaving thousands of ships stranded and affecting aquaculture farms.

"Although the temperature has stopped decreasing, sea ice has been continuing to grow," Zhang Qiwen, a sea ice expert at the National Marine Environmental Forecasting Center, told China Daily on Tuesday.

The peak of this year's sea ice may be similar to the level in 2010 when about 90 percent of Bohai Bay was covered by ice, the worst freeze in the bay in the past 30 years, according to Zhang.

Although there are no reports of oil or gas fields halting operations in China, sea ice experts at the center checked offshore oilfields on Tuesday, studying the situation and arranging icebreakers to guarantee operations.

Due to frequent cold snaps and precipitation over the past few weeks, the ice at Liaodong Bay stretched 100 kilometers from the coast on Tuesday, according to the center's latest satellite image.

The image showed ice in Bohai Bay reached 15,231 square km on Tuesday, about twice the average area for the same day in the past 25 years.

Thousands of fishing boats were frozen at ports in Tianjin and small cruise ships have suspended operations for safety reasons.

The situation is worse in Laizhou Bay, where the maximum ice thickness surpassed 30 centimeters and most ports were frozen.

"More than 26,667 hectares of aquaculture farms are frozen in Bohai Bay and Laizhou Bay, and fishermen cannot go fishing," said Li Li, a coastal police officer in Laizhou.

Qu Bo, who cultivates sea cucumbers in Huludao, a coastal city in Liaoning province, told China Daily that so far there has been no impact caused by the frozen aquaculture farms, but things may get worse as the ice is becoming thicker.

Fan Delai, deputy director of the Huludao oceanic and fishery administration, said waters off Huludao froze several days earlier than usual and may cause economic losses to nearby aquaculture farmers.

He added that in order to monitor the buildup of sea ice, three monitoring spots have been established and release reports on the ice daily.

Authorities in Juehua Island, the largest island in Liaodong Bay, have made preparations for the two months every year when residents are cut off from the mainland because the ice is too thick for boats to operate.

Yan Weiming, a 32-year-old fisherman on the island, said his family has stored enough food for the coming cold.

The China Meteorological Administration said on Friday that the national average temperature was -3.8 C in December, which is the coldest in the past 28 years. Hulunbuir in the Inner Mongolia autonomous region was even hit by a record low temperature of -46 C on Monday morning.

In 2010, China experienced the severest impact of sea ice in three decades with about 90 percent of Bohai Bay covered by ice, according to the State Oceanic Administration.

Liu Ce in Shenyang contributed to this story.

(China Daily 01/09/2013 page3)