If you are going to release fish, knowing how to handle them makes it more likely they will swim away safely.
"The fate of fish after release is primarily determined by angler behavior -Brownscombe et al 2017
Here is some excellent “why” and “how” information. It’s aimed at steelheaders but it stands up wherever you fish.
Keep Fish Wet and the Wild Steelhead Coalition have collaborated to highlight how people can safely play, handle, and release a wild steelhead to improve its chances of survival after it swims away.
There’s even a handy QR code thingy in the upper left corner of the infographic below.