(1) Your No. 1 sentence is quite good. May I just revise it a bit:
I saw a film on the Animal Channel about the group Greenpeace,
which fights to obstruct whalership whaling.
(a) It might be more diplomatic NOT to mention the nationality of the
whalers. This is a most sensitive issue. Everyone already knows their
(2) I am not too sure about the meaning of No. 2. Perhaps it means:
The whalers claim that scientific research is involved in the hunting and
killing of whales in the Antarctic Ocean.
(3) I am not sure about No. 3, so I had better not guess.
********** NOT A TEACHER **********