Catching keepers in deep water often means releasing fish that don't make the cut. In water over 50 feet deep, fish can often suffer from barotrauma where the air in their swim bladder expands as they surface abruptly on the end of your line. If released, this condition often renders them unable to submerge themselves and return to the bottom. Seeing as the whole purpose of releasing undersized fish is to further the health of the stock, then it makes sense that anglers do so in a way that ensures the fish survive.
Various devices have been developed for this purpose including many improvised solutions developed by anglers. For a time, venting tools which is basically a needle used to release air from the bladder, were commonly found. However, stickling the fish you are trying to save with a needle never seemed like a great idea. Descending devices use a weight to help the fish overcome the increased buoyancy resulting from barotrauma and return to their natural depths. Studies have shown that descending devices increase the survival rate of released fish.
Return 'Em Right is a new program to reduce catch and release mortality from barotrauma in recreational reef fisheries in the Gulf of Mexico. You can sign up today to receive a descending device developed through several years of research and funded through various conservation organizations.
If you don't want to wait for your free descending device, you can order one or just see what other models are available.