The steps you can take to keep the fish alive start before you catch it.
Different techniques can affect the survival rate:
A: Bait hooks are often swallowed and are more likely to cause serious injury than lures, which tend to be mouth-hooked.
B: Using single hooks will minimize lethal hooking and are easier and quicker to remove. Avoid using cadmium plated hooks, which are toxic when they decompose.
C: Catching the fish as quickly as possible will reduce exhaustion. Light tackl tends to prolong the fight.
D: Exhaustion comes much quicker to the fish in warmer water.
E: Handling should be kept to a minimum and be as gentle as possible.
Obviously, conditions determine techniques, and the desire for a sporting battle can conflict with some of these points. In fact the only way to meet most of them would be to jigfish with battery cable and back down like a big dog, and that's not very sporting. But keep these points in mind as you make your fishing decisions and you'll give the fish a fighting chance for survival.
At the arrow you see the tag, just a small thing that doesn't harm the fish at all.
Know how to tag
The first thing you should have is proper tagging gear. That means a tagging stick at least 4 feet long and NMFS or TBF tags. Tags are available through most fish weigh stations and fishing clubs, or contact the organizations below if you need supplies.
The preferred tagging zone is near the base of the dorsal fin, no closer than a foot to the head and gill plate.Insert the tag well above the lateral line running along the body. Placing the tag high on the body decreases the chance of causing serious injury to internal organs and reduces internal hemorrhaging, since the upper torso has fewer blood vessels than in the lateral line region.
The act of tagging is similar to gaffing in that you want to get it right the first time. Never try to tag the fish until the crew has it fully under control. Push the tag into the fish with a single strong thrust - the metal rod holding the tag should fully enter the flesh of the fish. And have a second tag unshipped and standing by ...just in case.
Know how to release
Never, never, NEVER release a marlin without first reviving it. Imagine you're found near death after a fight, and are brought home and left to die on your front porch by someone who leaves thinking they've done a good thing. That's what you do if you simply release a marlin without taking steps to insure its survival. It doesn't take that much time, and I swear to you it will be worth it ... more on that later.
Once the fish is controlled and tagged, you must remove the hook. Grab the bill with one hand (cotton gloves are good here ... the bill is just like a rasp) and use a pair of fishing pliers to remove the hook with your free hand. If the hook cannot be easily removed, or the removal itself may cause excessive injury, cut the leader as close to the hook as possible. Time is of the essence in this operation. Since both of your hands are on the fish, it's a good idea to have someone hold you by your rod belt as you work
Now it's time to revive the fish. If you have a swimstep, you can do this while lying on it (although you'll get wet); if not lean over the side ... but you definately need that helping hand on the rod belt now. Hold the bill and push it down so the fish's entire mouth is underwater. At minimun throttle, put the engine in forward gear if you have two, use only the one opposite the side from where you are working. As the boats starts forward, water will run through the mouth and over the gills. Now here's the reward I mentioned above: you will feel the fish come back to life you will see the color come back into his body. It usually takes 30 seconds or less, and the bill will begin to twitch ... the fish is telling you it's time to go. Gently release the fish and watch it gracefully sink out and swim away. It is the most incredible fishing experience you can have ...and far better a memory than any picture of a trophy fish on a meathook.
If You Catch A Tagged Fish
According to David Holts, who runs the tagging program for the NMFS, you should clip and save the old tag, and retag the fish before release. If you do intend to keep the fish, NMFS would like both the tag and a sample of the tissue around it, so they can study the healing process . Contact David for information on shipping the samples to him.
reprinted with permission from Southern California Marlin Online