Is no one going to chime in on this? I mean it is pretty clear that those fishermen are there to help you get super rare summon fragments faster.

There was a moment yesterday, before the actual events were up. Fishermen event was on. I think I saw someone post a thread about it.

You sweep instances to get baits to fish at 3 different areas i.e. Konoha, Toad Mount, and Land of Waves. Different areas use different types of baits (Low-Med-Adv.)

Luckily I had a play with it. You fish and you will get points to redeem prizes and certain chance to get "Fish box" that contains items i.e. lots of Dangos and other stuff.

oh, thank you, I'm sad I missed the small margin to try it