Fishing lockout?

[Nyalia]

yeah, just fish ONCE at another spot = unlocked

Exactly.

Note it's not necessarily another fishing hole, just another fishing spot. Like, move a few feet to the side and try again.

The only place this is a big problem is the Exploratory Fishing Hole in Coerthas (because it's so small). The workaround there is to fish from maximum distance and, if you get the message (or ever few throws) move to the maximum distance spot 120 degrees around the hole. Like, imagine a triangle around the hole with each vertex the max distance away where you can still fish. Fish at those points. It seems to look at distance from where YOU were when you "overfished," not the distance from where your theoretical hook would have hit the water.