SOUTH CHINA SEA -- Chinese fishermen are setting their eyes on the vast and largely untapped fishery resources in the South China Sea with the sail of a big fishing fleet to the region.

The fleet of 30 boats, including a 3,000-ton lead boat carrying fresh water, fuel, and other supply, arrived at Zhubi shoal for fishing on Wednesday, almost a week after it left port in southern Hainan province.

Fishermen of the island province have been fishing in the South China Sea for centuries but fishing in such a big fleet is a rarity.

Zhang Huazhong, head of the maritime and fishery bureau of Sanya city, said the big-fleet fishing is not a government-sponsored show. Instead, fishermen initiated it, and local fishing cooperatives organized the activity.

"We yearned for fishing in this region. But if we went alone, the risks of being caught in storms or harassed by foreign vessels were high," said Liang Yapai, head of one of the two fishing cooperatives behind the event. "Now, as we go together, we can sit down to discuss and find solutions to any problem we encounter."

Indeed, some fishermen complained that suspected Vietnamese fishing vessels were like "shadow" tailing the fleet along the way.

"There are too many of them," said a chief mate on the lead boat Qiongsanya F8168. "They shouldn't be fishing in China's waters. But for many times we just didn't know how to deal with them."

He said that one night he found a line of at least 40 Vietnamese fishing boats mooring on the sea. Lights shining from the boats was a spectacular scene to watch.

China claims sovereignty over an area of 820,000 square sea miles in the South China Sea, stretching from Qiongnan shoal in the north to Zenmu hidden shoal in the south, Hailima shoal in the east to Wan'an shoal in the west.

Vietnamese fishing boats are often sighted in Xisha islands in the western section of the South China Sea, Chinese fishermen said.

In recent weeks, China beefed up patrols in the region to protect the country's maritime rights and interests as fishermen complained of being frequently harassed or seized by sometime armed ships of neighboring countries.

In another move to assert sovereignty, China in June announced to set up a prefectural-level city - Sansha, which will administer over 200 islets, sandbanks and reefs in Xisha, Zhongsha and Nansha islands, covering 13 square kilometers in island area and 2 million square kilometers of water.

Hainan fishery officials estimate that Sansha hosts a fishery reserve of about 5 million tons. Annual sea catch lower than 2 million tons will be able to allow the environment to sustain. Hainan currently reports only 80,000 tons of catch every year.

Hainan aims to shift the focus of its fishery industry from near-shore fishing to far off-shore fishing. Fishermen are encouraged to "build big boats and explore the deep sea," said Ding Xiuhong, a fishery official of Sanya city who is on board the fleet.

"We are researching on the ways to explore the vast fishery resources in Sansha, in a bid to help Hainan fishermen raise their income," Ding said.

Big-fleet fishing, once proved successful, will be adopted for fishermen eyeing the catch in Sansha, Hainan officials said. The island province has 36 fishing cooperatives involving 3,000 fishermen.

"It is not a coincidence. I guess there will be regular big-fleet fishing in the future," said fisherman Huang Xiucheng.