I was able to get your email but I am not able to send a response right now due to problems with my server. They are upgrading the email portion of the server and although I can get emails I cannot send any out.
In regards to your question on how I get only female perch, my suppler seines his ponds early enough when it is very evident which ones are females by the distended abdomens. And I only purchase the females for optimum size and growth. It would be a waste of time to feed males for my market. However I apparently did not get all females from my first supplier (I have found out since he is somewhat of a shyster) as I have a few small perch swimming around in my bass pond.
And yes as you surmised female perch grow faster and larger than males.
You're probably aware of this, but one can also produce all female perch and other species by 1.) treating the fry with testosterone via their diet. This sex reverses the genetic females altering their chromosones 2.) the hormone treated females are raised to sexual maturity and their eggs are crossed with normal males. This produces all female offspring and leaves no hormone residue in the offspring.
Here's a link for some very good info: http://ag.ansc.purdue.edu/aquanic/ncrac/wpapers/yp32900.htm#BIOLOGY_AND_PRODUCTIO N_TECHNOLOGY