Interesting TV show

I'm sitting here, watching a show called "Whale Wars"
If you havent seen it, it concerns a group of people out to stop the Japanese whaling fleet, by using harrassing tactics like prop fouling lines, paint guns, etc.
The whalers are using water cannons and aggressive manuevering to try and stop them.

My question is whay arent the whalers using gun fire to repel the anti-whalers?
It seems that these anti-whalers, by using small boat attacks and their other tactics, would be guilty of piracy.
The skipper of the whaling ship has every right, and the legal duty, to protect his ship.

Its actually funny that the anti-whalers say they wont allow the Japanese to do anything that would endanger their own crew, but they dont seem to have any problem endangering the lives of the whalers, who are doing nothing illegal.