MANILA As the Indonesian army marched at the presidential palace in Jakarta in August to celebrate the nation's Independence Day, the navy and coast guard units were smashing holes in fishing boats that had encroached on its territory.
They sank 60 vessels that day, most of them were foreign-flagged. The record-setting action brought to 236 the number of illegal fishing boats destroyed since Indonesian President Joko Widodo came to power in October 2014.
Widodo has called this "shock therapy" to restrict illegal fishing, which officials estimate costs Indonesia up to $20 billion a year. The Indonesian archipelago, Southeast Asia's biggest, has the world's second-longest coastline and its largest tuna fishing grounds.
Indonesia used to take a low-key approach to safeguarding its maritime zones and has considered itself a nonparty to territorial disputes in the South China Sea, where its neighbors Brunei, Malaysia, the Philippines, Taiwan, Vietnam and China have overlapping claims. But China's increasing assertiveness in the nearly 3.8 million-sq.-kilometer waterway -- reflected in the adventurism and relentlessness of its fishermen to go as far as Indonesia -- has prompted Widodo to take a tougher approach.
Indonesia is not alone in its battle against seafaring trespassers. In March, about 100 Chinese-registered boats guarded by Chinese coast guard units were detected fishing near the Luconia Shoals, which Malaysia considers part of its territory. The Malaysian government quickly deployed units from the Malaysian Maritime Enforcement Agency and its navy in the area. In March, Vietnamese coast guard units seized a Chinese fuel ship in Vietnamese waters, and in May, the Philippine Coast Guard arrested 10 Chinese poachers who were found in possession of endangered black corals near the southern Philippine island of Camiguin.
In recent years, tensions in the disputed area have centered around fishermen, rather than military units. Analysts say countries including Vietnam and China have deliberately encouraged their coastal fishermen to operate farther afield in the South China Sea.
China has the world's biggest fishing fleet, and it is being used "to assert its sovereignty over the entire South China Sea," Jay Batongbacal, director of the University of the Philippines Institute for Maritime Affairs and Law of the Sea, told the Nikkei Asian Review in an email.
DOUBLE DUTY In the town of Tanmen on Hainan Island, China's southernmost province, fishermen are playing a crucial role in Beijing's maritime ambitions. A 70-year-old retired fisherman, who introduced himself merely as Li, said his job -- like many others -- was not only to catch fish. For years, he said, he had two duties when he left shore.
"As Chinese, we have to do one thing without complaint when necessary," Li said, referring to fishermen working as militia. "When we are told by the state to go to the South China Sea, no matter what, fishermen in Tanmen must put on [militia clothes] and sail."
When Li was still fishing, he would sail to the South China Sea with his colleagues for 100,000 yuan ($14,749) to 200,000 yuan per mission. Tanmen-based fishing boats are also equipped with advanced navigation systems that cost about 10,000 yuan, thanks to government subsidies.
Highlighting Tanmen's strategic importance, Chinese President Xi Jinping visited the town in April 2013 and gave a pep talk to local fishermen. "Please feel safe to fish," Xi was reported as saying at the time. He also told maritime militia members to "collect oceanic information and support the construction of islands and reefs," according to a report by the China Daily.
China has built at least seven artificial islands in the South China Sea and equipped them with runways and navigational support facilities to cement its territorial claims.
Some 300 to 400 fishing vessels are constantly anchored in Tanmen, and more than 1,000 local people make their living by fishing. Some of them, like 59-year-old Guo Hai, have grown increasingly cautious because of the risk of being arrested at sea. "As the South China Sea is dangerous, nobody wants to go there," Guo said.
Many households in Tanmen proudly display pictures of Xi posing with local people. "We can live in the town and work [at] sea without anxiety -- thanks to Mr. Xi," one fisherman said.
China is the world's largest fish producer, accounting for more than 17% of global output, according to a 2014 report by the Food and Agriculture Organization of the United Nations. However, stocks are disappearing. Fisheries resources in the East China Sea and Bohai, the innermost gulf of the Yellow Sea, are severely depleted, and only the South China Sea is in better condition, Chinese media have reported, citing information from the Ministry of Agriculture, which has blamed overfishing.
DEPLETED STOCKS China's annual catch has reached 13 million tons in recent years, much higher than the allowed volume of 8 million to 9 million tons, local media have reported, citing the ministry. In the Yangtze River, which accounts for 60% of the country's total freshwater fish output, the annual catch is about 100,000 tons a year -- less than a quarter of what fishermen caught in the 1950s, according to Chinese media.
If overfishing continues, China's more reliable source may suffer the same fate as the Yellow Sea. Already, fish stocks in the South China Sea have fallen by 70% to 95% since the 1950s, according to researchers at the University of British Columbia.
With the government's backing, Chinese fishermen have been emboldened to fish even beyond the "nine-dash line," a historical demarcation of Beijing's claim to more than 80% of the South China Sea. An international tribunal ruled in July that this claim has no legal or historical basis, but Beijing has refused to accept the ruling.
"Currently, fisheries [are an] important factor that influences China's policies towards the South China Sea," Zhang Hongzhou, an expert on regional maritime issues at Nanyang Technological University in Singapore, told the Nikkei Asian Review.
In the tussle for supremacy in the region, discussions have mostly centered on oil and gas resources. But some analysts say the prospects for oil and gas are overhyped. A U.S. Geological Survey study has found that the South China Sea contains some 12 billion barrels of oil and 160 trillion cubic feet of natural gas reserves. But since most areas with oil and gas resources are within the exclusive economic zones of respective claimant countries, they are not really in dispute.
Fish "are certainly more important in escalating the disputes and causing conflict than is oil and gas," said Gregory Poling, director of the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies.
Beyond depleting fish stocks, as fishermen become integral to their respective states' maritime strategies, they also represent a security risk.
"An incident involving fishermen is the most likely cause of an incident that could provoke a crisis," said Batongbacal of the University of the Philippines. "Militia vessels could do a lot of harm to other states' vessels, and if the other states retaliate to protect themselves, Chinese coast guard and military vessels could then step in to retaliate with overwhelming force, claiming 'provocation.'"
Poling said Chinese naval, air, coast guard, and paramilitary forces in disputed waters will increase rapidly as its military bases in the Spratly Islands become fully operational.
"That will lead to more frequent run-ins with fishermen and others from neighboring states," he said. "Given that, it is a matter of when, not if, another crisis will erupt because of a lack of professionalism at sea or a failure to de-escalate rapidly enough."
Nikkei staff writers Wataru Suzuki in Jakarta and Yu Nakamura in Tanmen, China, contributed to this report.