The recent issue of PB has an article about if fish grow during the winter, but the author talks about New York ponds and their temperature profiles. From that article, one would read that LMB have a very short and finite growth period in NY ponds due to fewer 'warm' days.
If you buy into that, then LMB may not be the optimal predator fish for your pond, but considering the actions you took in adding BG and culling LMB, I would want to see what results you get from that. I'd keep culling LMB, and be feeding the BG heavily.
And then see what happens.
