I'm surprised they are risking trawling there anyway. So much rubbish (including whole caravans) went out to sea during the big flood the bottom must surely be already littered with junk.

They need to do this via the media. Look what happened when the NZ Herald got hold of the Korean fishing boats story.
Once it gets publicised the rest of the media (TV as well) will start sniffing around and phoning various politicians for comment.

I've told them they should photograph or video the boats and send it to the media