Agree with others' input about culling.

I've found the best time to really put a dent in the crappie population is early in the year when they are schooled up.

You can catch them one after another, and that should help.

I'd also cull every one caught regardless of size.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."