Hi Cecil and thanks for the reply.

We caught some nice sized perch earlier this spring but lately nothing larger than 6-8". The larger ones may have had some winterkill but you would have thought I would have seen some evidence of it. I was chipping the dead catfish out of the ice and scooping them off the bottom, they seemed to be concentrated in one area of the pond.
As far as preventing winterkill, I purchased a small surface aerator in mid-January last year but apparently I was too late. We had a very tough winter in these parts, pond froze over in early Nov., then was covered with 2 1/2 feet of snow, then tried to melt for a few days, refroze and covered with several feet of snow again. There was 8" of ice then about 6" of slush then another 6-7" of ice on top of that in mid Jan. when I cut out a hole for the aerator. You could smell the gas escaping as soon as I poked through the ice. Hopefully, running the aerator all winter this year will prevent another kill.
Followed your advise and found a couple hatcheries closer to home that I didn't know existed. Does 15 sound like a good number to stock with my conditions? Thanks again.

Tyler