This is always a fun topic. IMHO, and from what I've read, it kind of goes like this: Tagging studies show very low (25% ????) re-catch rates for walleye. I don't think we are so silly as to think that these fish "learned their lesson" for trying to eat something with a hook in it, so we need to look at what/why these fish aren't showing up in later years. I'd suggest:
1. Any walleye caught from a body of water with temps above 65 degrees has a reduced chance or surviving.
2. Any walleye pulled up from a depth of 15 ft has a reduced chance of survival.
3. Any walleye that is exhausted from a lengthy fight because you choose to use 4 lb test line is likely to have a reduced chance of survival.
4. Any walleye that has been held in any way that doesn't support it's mid-section is likely to have a greatly reduced chance of survival. That's right, we kill lots of those nice 28" walleyes every whenever we hold them up by the gills for a quick picture before we release it and pat ourselves on the back.
The bottom line is that if you go out and catch 10 fish to bring home a limit of 5, you probably killed 6 or more fish for that five fish limit.