Ok, Winston, I'm thinking your situation may be a little more complex(perhaps a lot more complex) than the average stunted LMB pond.
You may have a couple of extreme X factors....1)Tilapia and 2) other possibly unknown species (e.g. walking catfish).
I did a great deal of research on Tilapia several years ago before stocking them in my ponds. I found what seemed to be very reliable reports in Mexican lakes which were targeting the American LMB fisherman $ experiencing significant LMB fishing declines when their lakes were protected from commercial fishing....sounds counter intuitive, doesn't it? Well, the explaination by several knowledgable folks was that the Tilapia in those lakes (they overwinter with ease in Mexico) without commercial netting were reaching a size and maturity where their diets changed from primarily veggie to small fish fry. This theory was substantiated by comparison to Tilapia lakes in which commercial netting was practiced...commercial netting of Tilapia = great LMB fishing, no netting = not great fishing. This interesting data was of little concern to me because Tilapia die off each year in my area.
That may be a factor in what you are seeing...but only one factor.
Other unknown factors involve the other species and what their characteristics may be. Something has caused the virtual elimination of the BG in your pond....and until you can figure out what that is, then stocking more BG is probably not the answer.
My guess, and its really a WAG, is that you are seeing the effects of a combination of negative LMB factors. 1) not nearly enough removal of small LMB, 2) adverse effects of Tilapia on recruitment of all other species 3) a possible feast or famine situation for the LMB and 4) simply unknown effects associated with other species.
The feast or famine comment relates to the following: Tilapia do not spawn below 68 degrees water temps. Your water temps in winter are most likely below their spawning level. Your pond probably has zero winter time forage and excess summer time forage....feast or famine for the LMB. When you combine that factor with years of stunting because of no LMB removal, you have a LMB population that can not effectively utilize the larger Tilapia forage that is present in winters and so many of them that there may not be enough to go around in the summer months. Thats out of the box thinking, on my part, and may be completely misplaced. But I think there is more to your case than meets the eye at first.
It seems to me you have a complex situation. Suggestions for improving: 1) find out what else is in there and what their characteristics are 2) remove small LMB 3) try to find a way to remove the larger Tilapia, the ones most likely to be predacious and if and when you can get those difficult factors ubder control, stock 6 inch CNBG.
I don't know, Winston, but I'm thinking your situation is more complex than we have been giving credit for and the solutions may not be as simple as the standard LMB stunting solutions....but thats just my 2 cents worth.
