Chunqx, theres a couple on the north arm, I think these are your options;
Blue Riviera Ph: 0402 459 293
Victor Boat Hire Ph: 0409 403 001
Portside Boat Hire Ph: 0438 087 885
I read an article recently about the local commercial fishos granted some sort of license to fish the north arm during winter/spring at night, so you may need to head down to the main arm and turn right up toward Kalimna/Nungurner or take the channel round the back of Rigby, Fraser & Flannagan Islands and fish the sand flats.
http://goo.gl/maps/Ayriz