There is a lot here on crappie in ponds. They are an enigma within a conundrum - no easy answers.
I do want to point out the issue of catchability. Lots here on the subject as well and worth looking at wrt your problem. Every pond specie that I know of has a built in fear/harm/stress release indicator or several. When a fish is caught (hook & line) it releases those indicators (visual/chemical/other) and the other fish know to watch out.
Crappie is about the last fish I have ever had a problem with catching multiples in one spot, actually just the opposite, I have pulled 30 and 40 of them in twenty minutes off of one little piece of brush during the spawn and even when they are not in spawn mode they seem to travel and dwell in schools, 9 times out of 10 where you catch one if you will cast back into the same place you will catch more, but then that's just been my personal experience, I do know catfish, especially BC are bad about making noise that will keep others from biting for 5 to 10 minutes almost every time.
