Dedi knows where the fish run strongest in Indonesian waters off the Natuna islands. The Chinese know, too.

Backed by armed Chinese Coast Guard ships, Chinese fishing fleets have been raiding the rich waters of the South China Sea that are internationally recognized as exclusively Indonesia’s to fish.

While Mr. Dedi catches the traditional way, with nets and lines, the steel Chinese trawlers scrape the bottom of the sea, destroying other marine life. So not only does the Chinese trawling breach maritime borders, it also leaves a lifeless seascape in its wake.

“They come into our waters and kill everything, said Mr. Dedi, who like many Indonesians goes by a single name. “I don’t understand why our government doesn’t protect us.

Wary of offending Indonesia’s largest trading partner, Indonesian officials have played down incursions by Chinese fishing boats, trying to avoid conflict with Beijing over China’s sprawling claims in these waters. But with the Chinese presence growing more aggressive, fishers in the Natunas are feeling vulnerable.

“There was a vacant period, then China came back, said Ngesti Yuni Suprapti, the deputy regent of the Natuna archipelago. “Our fishermen feel scared.

The latest episode occurred in February, fishers said, when Chinese fishing boats flanked by Chinese Coast Guard vessels dropped their trawl nets yet again. It seemed as if the coronavirus outbreak peaking in China at the time hadn’t diminished the country’s global ambitions.

The Indonesian fisheries ministry, however, denied any intrusion by the Chinese. The Indonesian government does not provide data on incursions by foreign fishing boats.

China’s illegal fishing near the Natunas carries global consequence, reminding regional governments of Beijing’s expanding claims to a waterway through which one-third of the world’s maritime trade flows. But local leaders in the Natunas don’t control what happens near their shores.

“We only have authority over our land, said Andes Putra, the head of the Natunas’ Parliament. “The provincial and central governments handle the seas.

Yet with multiple agencies responsible for protecting the seas the navy, the coast guard, the marine police and the fisheries ministry, to name a few decision-making is diffuse, analysts said.

“There is a lack of a single coherent lead agency or a single coherent policy for maritime security, said Evan Laksmana, a senior researcher at the Center for Strategic and International Studies in Jakarta, the Indonesian capital. “The Chinese can take advantage of that.

Chinese impunity was on full display in January when President Joko Widodo of Indonesia visited the Natunas.

“There is no bargaining when it comes to our sovereignty, Mr. Joko said. Earlier, Indonesian fighter jets buzzed the sky, while warships patrolled the seas.

But the day after Mr. Joko left the Natunas, the Chinese showed up again. Its fishing fleet, backed by the Chinese Coast Guard, took days to leave the area, local officials and fishers said.

The fisheries ministry denied that any such incident had taken place.

On Chinese maps, a line made of nine dashes scoops out most of the South China Sea as China’s. One of the dashes slices through waters north of the Natunas.

While Beijing recognizes Indonesian sovereignty over the Natunas themselves, the Chinese Foreign Ministry describes the nearby sea as China’s “traditional fishing grounds.

“Whether the Indonesian side accepts it or not, nothing will change the objective fact that China has rights and interests over the relevant waters, Geng Shuang, a Chinese Foreign Ministry spokesman, said in January.

In 2016, an international tribunal dismissed the nine-dash line as legally baseless. The Chinese government ignored the ruling.

Instead, Beijing continued turning contested atolls and islets into military bases from which China can project its power across the South China Sea.

2020 The New York Times Company