Do you love big bluegill?
What Ryan said. If you are interested in big bluegill, which I'm guessing you are to some degree since you're here, harvesting bass will mess that up. Ponds with 11" bluegill in your region don't come along often; that pond right now is something special. It would be a shame to mess it up. There are probably other ponds in the area that have better bass fishing - I'd suggest fishing those for bass, and leaving this one the way it is.
Uncontrolled ice fishing can decimate a population of big BG's. Lots of times they school tight in the winter, and , once located, can be hit hard. I would recommend the same thing I always do, returning the biggest males, and harvesting the smaller ones. A fish that is 11.75" and 21 ozs. has a relative weight of around 91%, that's not too bad but it could be better. I would try and remove some of the smaller BG's, say 8" and under. Do you feed the fish on this lake? It makes all the difference in the world.
11" is considered extremely rare in our waters. Like Tony said, best to preserve as much of the large ones over certain length. I, and a few of us who love panfishes over here, preserve anything larger than 9" when possible. We will harvest females after they off-load their eggs. Otherwise, try to keep those wonderful size fishes. Wow, 11-inchers. Man, that would be the day when I can land a few of those.
have you ever thought of throwing in some crappie in and taking out alot of those small bass? I dont know what this would do but I imagine that the crappie would act like those smaller bass and you have a bonus when fishing for those big bluegills.