The claims vary according to the mood of whichever power is feeling feisty. Those little islands, rocks and reefs that nobody ever heard of and on which nobody ever lived, are vital in staking a claim to exclusive economic control over even more seawater. The fish don't mind. Here is what the claims look like these days.
China declares that it is regulating the fishing fleets in order to ensure that the commons are not despoiled by over-predation. That's a mighty generous gesture and so reasonable from most points of view. There are well over a billion Chinese that like a bit of fish now and then so you could say they have a vested interest in preserving the sea-commons.
On the other hand, so to do the various countries that make up the EU and they actually fight over fishing rights with guns and bullets.
My advice to the unfriends of ours who share waterfront with China's sea; you better arm yourselves. I'm hoping that 'non-aligned nations' crap you were peddling a decade or two ago is matched with your very own Juche in so far as defending your fish and your oil. I wouldn't want to be the one that had to explain to the lynch mobs that you were counting on John Kerry and President Obama to look after your vital interests and keep them safe.
Of course there's always the UN if you're feeling lucky.