That stinks! As I was reading your post I was like "ahhhh man that sucks" as soon as I got to the part about the mandarin! I love my mandarins and would cry if that happened!

You could always use traps...but the thing I hate about traps is you always catch the ones you didn't want to catch and in this case that might not be a good idea. IE;...you set the trap, go to sleep and wake up with a half eaten powder blue and a happy lobster both in the trap :(

I would save yourself the time upfront and just set a couple of hours aside to move the reef and catch the little *******

Good luck.