The geopolitical struggle between China and the Philippines has strangled Filipino fishermen’s access to some of their richest fishing grounds .

“Kaya pa, I can still do it,” Rony Drio takes aim with his handmade speargun. A split second later, the sharp end pierces the wooden target set against a mango tree outside his home on the northern Philippine island of San Salvador.

Drio, 56, has been spearfishing since he was a teenager and, like most men in San Salvador, is an expert marksman with the speargun, a classic fishing tool of the Philippines. He can still dive up to 15 meters—holding his breath for nearly eight minutes at a time—as he hunts grouper, red snapper, and mackerel.

So no, it’s not age or infirmity that is threatening his livelihood as a fisherman. It’s geopolitics. For Drio, a coral atoll called Bajo de Masinloc, in the West Philippine Sea about 140 miles offshore from San Salvador—is a key fishery that has sustained his community for generations. To the rest of the world, that area is known as Scarborough Shoal: a clutch of rocks that has become a frontline of naval conflict with China. It’s a flashpoint that menaces relations between the two Asian countries and epitomizes Beijing’s rough treatment of smaller neighbors it says are friends.

From San Salvador, it can take up to 18 hours in small fishing boats—in good weather—to reach Scarborough Shoal. The triangle-shaped ring of reefs around a vast lagoon has long provided sanctuary to storm-battered ships and food for San Salvador. Fishing is the primary source of income for the more than 500 households on the idyllic island of San Salvador, where ramshackle bungalows nose towards white sandy beaches and only the occasional day-tripping tourist visits its shallow coral reefs.

The Scarborough Shoal, named after a British ship that grounded on the atoll nearly three centuries ago, lies within the exclusive economic zone of the Philippines. Yet to Beijing, the shoal is the strategic center of the South China Sea and in the heart of shipping lanes crucial to China’s multi-trillion-dollar maritime trade. There are also substantial untapped oil and gas reserves under the seafloor there. Over the past decade, China has intensified its claim to “historic rights” to disputed waters, deploying naval and fishing vessels in the region that block Filipino fishermen from accessing the shoal.

Beijing refuses to acknowledge the validity of a 2016 Arbitral Tribunal ruling that favored the rights of Filipinos to fish the waters. Yet an official international ruling on sovereignty has never been made, leaving access to the waters to the whims of the Chinese coastguard patrols. On rare occasions, the fishermen are allowed in; usually they are not.

The cost of geopolitical squabbles is being counted out in the nets of Drio and his fellow fishermen, with income from the seas dropping by half in recent years. In his village, access to education and state services is weak, leaving the younger generation with a limited future as fishing becomes increasingly perilous.