12” limits are only for white crappie lakes, white crappie grow longer but not as wide as blacks, in a black crappie lake or with slow growth and with a limit that long you would have a stunting of small fish, 10” has been thouroughly studied on jordan as well as a couple yadkin lakes and it was implemented on jordan and works tremendously well, but the nc wildlife does not base its rules from a biological stand point, if you believe they do then you are being fooled, i could elaborate but its to long for here