i asked this question at TFF...they told me to bring it over here.

I have a hunting lease with a 15 acre or so lake. it is spring fed (clear) and full of food (minners, crawfish, etc)...i have fished it kinda hard and have yet to catch a fish over 10 inches or so. i have a feeling we need to cull out the small fish, which we are beginning to do...however, i am SURE there are some big sows in there somewhere? what do you think? i have tried large/small/ baits of all kinds and fished them just about every way i can think, but still nothing but dinks.
any ideas? should i ASSUME there other other species of game fish in the pond (cats, crappie, etc?) i have only caught bass out of it so far.

I wouldn't assume you have other species. Although rare in Texas, I have come across a number of ponds and lakes with bass only. It would be wise to survey your lake, find out exactly what's in it, then decide what to do. One thing for sure, harvesting small bass will help. And, don't be surprised if you don't see a big sow. It doesn't necessarily happen that way.
You may need to build the food chain, while culling bass, but a survey would certainly tell the tale.
Where in Texas is your lake?