Well, in my view/experience, the pond may be light on forage. An initial stocking of 3000 gills/redears would have been better, IMO...even more if practical.
You can get a great deal
of very useful info from recording relative weights...see the article at http://www.aces.edu/pubs/docs/A/ANR-1193/ANR-1193.pdf
There are other good sources on relative weights out there available also. A little time spent reading up on it will be worth your time.
So, if you are light on 'gills. You have some good options:
1) stock about 30 pounds or more of Tilapia when water temps get to be reliably above 65 deg. They will take a lot of pressure off your 'gills and allow then to repopulate naturally.
2) Take out all small bass, anything less than about 13, 14 inches
3) maybe add some adult bluegills...expensive option but adding smaller 'gills a waste of money.
4) other forage possibilities include big shiners...run about $10 per pound at my bait shop and maybe try threadfin shad...but your pond is probably too small and too far north to expect to get them established, so expensive snack.