I'll let you decide on which ones to remove.
I'd think long and hard with a pencil and a piece of paper figuring out the size of the LMB in the pond, and the size and quantity of BG that I could source for the pond. BE VERY CAREFUL that you can identify a Northern BG. There are other fish that people think are BG, but aren't. Hybrid BG won't spawn enough to feed the LMB. RES won't spawn enough to feed the LMB. Crappie are a no-no in a small pond - they spawn before LMB and BG, eating both and competing with LMB for food when smaller.
Usually you want 20 to 30 BG per LMB. Probably 30%-50% more if you are stocking BG in the size range that the LMB can eat.
Also, be careful if you transfer fish from another BOW (Body of Water). You can bring in parasites, diseases or unwanted plants with the fish......
There is a relative weight (WR or RW) chart in the archives. Open it and print out the one for LMB. When catching LMB, remove the ones that are under 100% WR. Right now, probably all of them are over 100% WR because of being in pre-spawn condition. After spawning they'll weigh a lot less.
Somewhere on here there is a study that was made, showing the % of each size class of LMB in a healthy pond. That can give you an idea if what the size distribution in the pond should be.
If you want to track individual fish, Greg Grimes
http://lakework.com/ (and others - Herman Brothers, etc.) sell a fish tagging kit so you can tell if you've caught that particular fish before. A scale that can weigh in 0.1# increments and a good ruler along with a note pad to record the fish caught are very good management tools.