I have witnessed crappie spawning alot deeper than most would believe, especially when the water is gin clear in deep lakes because of drought conditions, such as we now have. When the eggs are mature, and ready to drop, they cant just hold the eggs until the temperture gets to a given number, they re gonna deposit those eggs in the best place they can find, at the time they are ready. If you go into a cove on a lake and its really clear, you arent going to catch anything near the bank, look deeper, or go to a cove on a north bank thats stained. Also, think of this,, if a crappie is spawned on a logpile, or brushpile, in deeper water, because of drought conditions, in say 12 feet of water. when that crappie matures to reproductive age, where do you think she will likely spawn her eggs? I think the same place she was spawned if conditions are similar. There ALOT more going on during the spawn period than temperture " seasonal migration movements. I believe they will spawn as shallow as they can, but deep if they need to. I think if you pay too much attention to water temps, your gonna miss the bus. start looking for spawners abt 2 weeks after the last coldfront, and pay attention to water clarity, and baitfish locations moreso than anything else. Alot of lakes will likely be low this coming spring, so start deeper and work your way shallower, instead of the other way around and you might find the crappie nobody else will find. This is just my opinion, based on my personal experiences, and Im sure theres others, just sharing mine.

Is the temperture measured at the surface or at a given depth?
Good post, i will keep it.