Pointblank, it almost seems like your whole argument about the trawling stuff boils down to some form of misreading of some international conventions here.
No matter what else we could dig up here, the provisions of UNCLOS are clear. Though I don't agree with ZTZ99's very violent solution, he does have a valid point.
UNCLOS does NOT give the right of FREE passage in a country's territorial waters. It gives the right for INNOCENT passage. Meaning passage is only allowed as long as the ship does not in any way threaten the host country or its policies. If there is any reason to doubt the -innocent- nature of a ship (or, in your example, a fleet of ships), then the host country can deny the ship(s) entry into its waters. If the offending ships do not respond, the host country can board the ships, ram them, shoot warning shots or do anything in their power to stop the ships. In a tense situation, non-innocent ships would be the ones doing anything else than steaming at full speed to get out of territorial waters as soon as possible.
Now, what is more is that inside a country's EEZ (exclusive economic zone), the host country controls ALL economic activity. This includes trawling. Any trawlers entering the zone can be turned around by the coast guard (or, read above). That is, unless they have a logical reason to be there outside trawling. In your example, the trawlers are trawling. Thus conducting economic activity. Which would be unlawful.
If we are talking about a SOSUS-system outside China's EEZ, we're surely entering the waters of South Korea or Japan, which would most likely be impossible to do, as these countries would surely know if the Chinese were deploying their system there, and could thus simply disable the system as the Chinese are laying it, as they are at full right to dispose of anything inside their waters.
PS: When talking about the Geneva convention etc. I think you guys forget one thing. The UN Charter is lex superior, meaning if in dispute, it trumps all other treaties. The UN Charter makes it clear that all countries are allowed to defend themselves with arms. Provision no. 2 is to have the response be proportionate to the threat. If a fleet of trawlers is damaging your submarine defence, then they are causing major and critical damage to China's defence ability, thus allowing a similarly urgent and effective military response. The rights of a few fishermen WILL be trumped by a major power's ability to defend itself.
