I found a great spot that is set apart from the battleground area even though you get flagged as soon as you enter. You're in Wintergrasp, there's not much you can do about that, but I didn't see one single person while I was there. Wranngar can hold his own but it has been a looong time since I did any PvP on Gomorra.


So I had good luck in the southeast corner of Wintergrasp and got in and out on both without any PvP resistance. I did this during a time when we were in control of Wintergrasp, but where I was fishing I don't think it would have mattered if the Horde controlled it or even if we were in battle.
Update: I have had just as good luck flying into the Alliance flight point in Wintergrasp and fishing in the Sunken Ring right there. If you have the flight point it will be quicker and easier to just fly in, fish there, and fly out.
This was the last of the 5 daily fishing quests Marcia Chase had for me to do so when I turned these in on Gom and Wrann they both got the achievement Chasing Marcia.
Good Luck :)
-Wranngar