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

The fleet of 30 boats, including a 3,000-tonne lead boat carrying fresh water, fuel and other supplies, arrived at Zhubi Reef for fishing on Wednesday, almost a week after leaving port in south China’s Hainan province.

Although Chinese fishermen have fished in the South China Sea for centuries, the size of the fishing fleet makes it a rarity.

Zhang Huazhong, head of the maritime and fishery bureau of the city of Sanya, said the fleet was not organized by the government, but by local fishermen and fishing cooperatives.

“We yearned to fish in this region. But if we went alone, the risk of being caught in storms or harassed by foreign vessels would be high,” said Liang Yapai, head of one of two fishing cooperatives that organized the fleet.

Some fishermen have complained of foreign fishing vessels, allegedly from Vietnam, like “shadows” following the fleet during their journey.

“There are too many of them,” said a chief officer on the lead boat Qiongsanya F8168. “They shouldn’t be fishing in China’s waters.”

The officer claimed he saw at least 40 Vietnamese vessels moored in the sea at one night.

China claims sovereignty over Nansha Islands, an area of 820,000 square sea miles stretching from Xiongnan Reef in the north to Zengmu Hidden Reef in the south.

In recent weeks, China has beefed up patrols in the region to protect the country’s maritime rights and interests, as fishermen have complained of being harassed by foreign ships.

In another move to assert sovereignty, China in June announced to set up a prefecture-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 is home to fishery reserves of about 5 million tonnes of fish. Annual sea catches lower than 2 million tonnes will allow the local fishing industry to develop sustainably, they said.

By now, fishermen catch only 80,000 tonnes of fish every year, they added.

Hainan aims to shift the focus of its fishing industry from near-shore fishing to far offshore fishing. Fishermen are encouraged to “build big boats and explore the deep sea,” said Ding Xiuhong, a fishery official from Sanya.

“We are working on ways to explore the vast fishery resources of Sansha in order to help local fishermen raise their incomes,” Ding said.

Large-fleet fishing will be adapted for fishermen in Sansha if proven to be successful, provincial officials said.

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