"For some reason the Japanese commercial guys think they own the water." I experienced that attitude first hand, and was told as much by my Japanese in-laws. I was also told to smile back and to politely ignore them, even when they said: "#@! Gaijin @%&$!!!"
Sumimasen!
Pulling up a sabiki rig full of aji right in front of them would almost always set them off. I soon learned not to fish in the middle of the local fishing fleet.
Btw, where do you get your Japanese tackle? There used to be a high end tackle shop in the Daiei Mall, but I hear that it is now closed. I used to spend most of my allowance in there.