Does China interfere with commercial shipping passing through the Taiwan Straits?

I have read that China considers the Taiwan Straits to be its "sovereign territory" which differs from international law that defines bodies of waters 12 miles or more offshore as international waters open to all.

Is China's claim merely words, or do they interfere with merchant shipping passing through the straits? By "interference" I mean: (1) stopping vessels with warships and boarding them and inspecting them, (2) requiring vessels to get permission to pass through the straits, (3) requiring vessels to identify themselves, and/or contact Chinese authorities to be able to pass through the strait, (4) forbidding vessels of particular countries to pass through the straits.