The fish descender has got to be better than piercing the air bladder with a needle. You can use the design in that link with the hook barb pushed down, or you can also just attach a binder clip (used for paper) to the line and clip it to a fin or jaw. A gentle tug when you reach depth, and the fish will pull right off.
This can also be modified using a clip or ring to slide down your downrigger cable, so you can descend a fish while you keep trolling. Towing them around on the surface to revive them does not help the air bladder, or the temp change. Descending them back down to the right temp and pressure seems best.