Pop Line - Left Mouse Click (x1).
Jerk Line - Left Mouse Click (x2).
Slow Reel - Hold Left Mouse Click.
Fast Reel - Left Mouse Click (x2) and then hold.
Once a fish is hooked alternate between a slack and taught line and keep the marker within the secure area of the fishing bar.
Follow ingame tutorials for additional info.
Spoon - Slow reel.
Jig - Alternate fast reel and stop.
Fly - Cast and wait. Recast if no bites in a few seconds.
Plug - Alternate slow reel and pop line.
Bait - Cast and wait. Recast if bait dies in the water.