There is a BIG diference between putting your finger under the gill plate and putting your finger in the gills.
Not all fish released after being hooked and fought will survive and to think so is only fooling yourself. There is a LOT of stress put on a fish during the fight, and many do not survive, even if it swims away right after being released.
If you are really worried about keeping those fish alive, don't hook them in the first place.