Just a thought on this topic.
Making sure all toons are lvl 1 (option to put newbie points in to fishing) and give them 15mins Fishing time in each zone you choose.
Put them in teams of 3 or so ( Makes fishing alot nicer if you are in group and have someone to chat to.)
Try and pick zones that have something unique about them. i.e OOT has seaweed, CS has Cod.
Give people bonus points if they catch a specific zone item, and say 1 point per fresh fish...Try and stick to things stackable as level 1's are limited to 1 backpack..in other words those rusty daggers and shoes get tossed back in.
Might take a bit to research where and what fish..Do a test run and fish a few areas as well as a safe place for a lvl 1 toon.
Don't forget FV has different size fish too. The bigger the fish the more points they get =D..
Hope this helps.