I don’t know of any really easy way to do this. The first thing I can think of is mostly doing it yourself. Basically I would decide how many segments I would want the curve to have and then draw each segment on the HUD canvas using Draw3DLine().
Maybe another thing that might work is an animation tree. You could make nodes that bend the pole when the fish is pulling on it. You could also have a loose and taut state for the line, and you could move the line and the rod’s rotation based on direction to the fish.