Ever catch a fish a fish that was too small to keep, and you knew as soon as you reeled him in that you were going to have to release him? But then as soon as you try and remove the hook, you have a problem! The hook is in too deep. It's stuck!
You may be trying really hard to remove the hook carefully so as not to hurt the fish, but no matter how hard you try, the hook is stuck. The fish may be under the size limit, and you know you can't keep him.
But you also know that the more you handle the fish and struggle to remove the hook, the more damage it will do to the fish. And you know there is no way the fish will survive long back in the water with damage to the lip (from hook removal) and scales (from handling him).
What should you do?
There is a solution to this problem that works for the fish - even though it might not sound too attractive to us humans (unless you're in to body piercing).
When faced with this problem, the best course of action is to cut the line as close to the hook as possible. Many hooks will dissolve in the underwater environment - unless they're made of stainless steel.
So when fishing, the best practice is to never use stainless steel hooks. If you do, you're back to the initial problem without a good solution!