Mario Forones, 54, who returned in late March from a trip, said several Chinese Coast Guard ships constantly circled the reef while one planted itself inside, blocking any boats that might get past the first line of defense.

“If you get too close,” he said, “they come at you in rubber boats and yell in English: ‘Go away! Go away!’ ”

According to the Philippine military, some fishermen have gotten rougher treatment. During prime fishing season in January, officials said, Chinese ships used water cannons to drive off some of the Philippine boats.

Though fishermen from more distant parts of the Philippines venture into these waters, they need larger, more expensive vessels to reach the area, load their catch and make it home, so they rely on it less. But for the people of Masinloc, the closest point in the Philippines to the shoal, the reef is considered an extension of the town.

From Masinloc, a 30-foot fishing boat with a single engine can reach the shoal in about 18 hours. That had allowed the small-time fishermen to regularly take in more than a ton of fish a day even with their minimal resources.

The catch is especially crucial because the town has so far missed out on the economic surge that has made the Philippines one of the fastest-growing economies in Asia. The moribund town center features an open-air market and a mostly abandoned shopping mall. Vendors sell slippers and hot dogs from makeshift stalls, and customers are scarce.

Mayor Desiree Edora said the town of about 45,000 was struggling to absorb the loss of business as fishermen returned from the shoal with smaller catches, affecting everyone from ice vendors to truckers to restaurant owners. Although she said she did not add up the losses in what is a lightly regulated industry here in Masinloc, she said they were substantial. The local economy is based on fishing, rice farming and a coal-fired power plant that feeds electricity into the national grid. There are no factories or call centers to absorb the fishermen if they can no longer make a living off Scarborough.