I suspect more fish are killed because tournament fishermen do not know how to bleed pressure from swim bladders than in other reason, especially in the summertime. If a fish is not bleeding when placed in the livewell and dies afterward, something is wrong.(assuming a good livewell).Many of the fish that die just needed fizzing, pressure relieved from their swim bladders. Most fish that need fizzing(pressure bleeding) will swim at the top of water and not be able to stay on the bottom, will stay on their side a lot, or be upside down. If they display any of these symtoms, they need fizzing to stay alive and nothing else will help. All the rejuvinate, ice, o2 or anything else will not save them.
Actually injecting pure oxygen into the water might but most fishermen don't carry pure oxygen in their boats.
Fish that need fizzing are usually caught in excess of about 12 feet, however there are exceptions to every rule. Over 12 feet you can just about be assured they need fizzing. These fish would normally do this automaticly themselves if left in the wild but due to the stress of being caught and placed in the livewell many will not in the livewell.
It is a very simple procedure and gets easier with practice. It does require a syringe and needle. I'm not sure what size but the needle needs to be about 1 inch long and the syringe about the size that is used for a flu shot. I actually got one from my doctor but you can get one at a co-op or even your vet. One of the tournament trails that I fish provides them free of charge and will teach this procedure to anyone that ask. First throw away the plunger from the syringe.
The procedure:
While holding the fish by the lower lip with one hand lower the fish into the livewell water. With the other hand holding the syringe/needle slowly insert the needle down the fishes throat straight thru the middle of what looks like an a??hole until bubbles start appearing in the syringe. Hold in that position until bubbles stop. I have never measured the depth of the needle but I would guess 1/2 inch. The syringe must have water in it to see the bubbles therefore the fish must be in the livewell water. After the bubbles stop remove the syringe/needle and you are done. Keep an eye on the fish, occasionally they need additional fizzing, if so repeat the procedure. This will not harm the fish and will save its life if you intend to weight it later.
This can be done through the side of the fish, and was for years, but down the throat is much easier and more accurate(at least for me). If you are a tournament fisherman you need to learn this procedure and use it. It is really easy to do and we owe it to the fish..........
I don't have time to proof read, I hope it makes sense...........Al