you fish in the blue looking for large pelagics you use floating lines and buoys. Once you hit a big fish, if you don't want to let go of the rifle behind the fish, it is a good idea to have a system of releasing the rod from the rifle, which allows you to return to the surface with the rifle in your hand and let go of the fish bound only to the floatline and buoy.
All of this is doable with this simple accessory that transforms any rifle for rod release.
 
Version with swivel and clip.