I am no means an expert but I'll give you my opinion. Heck its free. 3-4" crappie in 2009 would probably be 2 year olds. They would have been capable to spawn in 2010 as 3 year olds. For sure in 2011 as 4 year olds. 2 growing seasons for your originals, at least in my ponds, would make them between 7-8". My guess is the fish caught last weekend were from your original stocking. Your offsping would now be in the 2-4" range depending on a 2010 or 2011 spawn.