BG can and do stunt (more up north) and then often LMB will not reproduce. See this from PSU on the subject.
In addition I have seen this event.
https://extension.psu.edu/management-of-fish-ponds-in-pennsylvaniaSTOCKING BASS-BLUEGILL PONDS
When small bass and bluegills of the same age were stocked simultaneously in Alabama, balanced populations always resulted. When this stocking strategy was followed in the North, the result nearly always was a stunted bluegill population and a bass population unable to spawn successfully. Research at Cornell University showed that to achieve successful bass-bluegill populations in northern states, the initial stocking must consist of bass that are at least 1 year older than the bluegills. This can be achieved by stocking yearling bass 1 year ahead of yearling bluegills or combining 2-year-old bass (over 6 inches) with yearling bluegills less than 2 inches long. Researchers currently believe that the proper number of fingerling fish to stock is 100 bass and 200 to 500 bluegills per surface acre. This stocking strategy has been shown to be successful in Pennsylvania ponds.
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The influence of stunted body size on the reproductive ecology of bluegill Lepomis macrochirus
D. D. Aday, C. M. Kush, D. H. Wahl, D. P. Philipp
Research output: Contribution to journal › Article
Abstract
Although stunting is a common phenomenon in fish populations, the consequences of stunted body size on the reproductive ecology of individuals has received little attention. The present study compares the reproductive ecology of bluegill in established stunted and non-stunted populations. Three ponds (two non-stunted and one stunted) were monitored for spawning activity throughout the summer. Parental male bluegill from both non-stunted populations were older, larger, and had greater mating success (number of eggs or fry within nests) than parental males in the stunted population. Stunted bluegill also experienced a shortened reproductive season owing to the delay in onset of spawning. The present study demonstrates that individual size and population size structure can have a marked influence on the reproductive ecology of bluegill.
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