Has anyone here ever seen a real life example of Bluegill taking over a pond? I'm starting to think it's a myth.

Now, I very familiar with the issue of Gizzard Shad taking over a pond. Adult Gizzard Shad grow too large for LMB to eat. When those large Gizzard Shad get crowed, spawning declines. Without successful baitfish spawns, the predator fish fail to grow. Thus allowing even more over-sized gizzard shad to escape predation, and so on.

My understanding is that overpopulated Bluegill will stunt, making them easy prey for LMB. Plus even if some Bluegill grow large enough to escape LMB predation, they still spawn well. So there's no way they can take over the way that Gizzard Shad do. For this exact reason they make a great forage fish.

If someone says they've seen it happen, I'll believe you. Otherwise I'm calling this one a total myth.

-Scott

I'm with you Scott, I can recall many ponds that have overpopulated and stunted with LMB (and even CC), but don't remember any that went that way with BG...Not that I've spent alot of time at alot of ponds. Just saying. I think that the high tendency for LMB to overpopulate reduces the likelihood that the BG will. I do believe that if a pond was just stocked with BG you would see that's it's not a myth, but I have know no one to just stock panfish without LMB.

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-pennsylvania

STOCKING 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.

More

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.

Do you know how the Bluegill were interfering with the LMB spawn?

Relation of Largemouth Bass Reproduction to Crowded Sunfish Populations in Florida Ponds
D. Hugh Barwick
Florida Game and Fresh Water Fish Commission, Eustis, Florida, 32726 USA

Dennis E. Holcomb
Florida Game and Fresh Water Fish Commission, Eustis, Florida, 32726 USA

D. Hugh Barwick
Florida Game and Fresh Water Fish Commission, Eustis, Florida, 32726
Dennis E. Holcomb


Abstract
Largemouth bass (Micropterus salmoides) were studied in an effort to determine if a repressive factor or predation by sunfishes (Lepomis sp.), or both, caused failure of bass reproduction in ponds crowded with sunfishes. In addition, we observed anosmic bass to determine if lack of olfaction would allow bass to spawn, in the event that a repressive factor operating through the sense of smell was the inhibitor. However, neither a repressive factor nor sunfish predation was believed to be responsible for lack of reproduction. Lack of reproduction was apparently associated with a physical factor that in some way interrupted normal bass breeding activity.


Behavioral Suppression of Spawning in Largemouth Bass
by Interspecific Competition for Space
Within Spawning Areas •
STEPHEN LEE SMITH
Florida Game and Fresh Water Fish Commission
Eustis, Florida 32726
ABSTRACT
Florida largemouth bass, f ail to spawn i n association w ith
Dense p opulations o f stunted sunfish. A recent study indicatedt hat a "physicalf actor" rather
than a chemical factor may be responsible.
Three hatcher• pondsc ontainingm arkedb assw ere stockeda t different pointsi n the bass
reproductivec yclew ith concentrationosf sunfishk nownt o suppresss pawning.I t was determined
that reduced or complete inhibition of spawning of largemouth bass is related to interspecific
populationd entities in the spawning area and is behavioral in nature. Suppression is linked to
aggressive interaction with other species,primarily affects the male bass, and is effective in
suppressing the spawning behavior sequence even before nest construction.
Other workers have reported the failure of
largemouth bass to spawn in the presence of
large numbers of sunfish and concluded that
failure was due to either sunfish predation on
the eggs (Swingle and Smith 1943) or to a
repressive factor excreted by sunfishes which

Barwick and Holcomb (1976) were the first
to indicate that some other factor may be
responsible. By segregation of bass and sunfish
while allowing free flow of water between areas
they obtained successful bass reproduction
and concluded that suppression of spawning
was probably not due to a chemical substance
excreted into the water. It was postulated
that "lack of reproduction was apparently
associated with a physical factor that in some
way interrupted normal bass breeding activity."
The study reported here was an attempt
to determine the nature of this "physical
factor" and the point in the reproductive cycle
at which it is effective.

That report makes me wonder if a pond with an ample population of BG/GSF, where there is only a limited population of LMB will ever reconcile a successful spawn by those LMB.

If that is the case, then what number of LMB would be minimally needed to attain success?

Fascinating the differences between northern and southern ponds.

The bottom line is that every pond is unique. Or, as often said,we really don’t know. Eric, I did not know that Swingle was studying this stuff in 1943.

I saw several ponds that were effectively taken over by BG when I was a kid (1960's). These were ponds that were "managed" by taking out every eating sized fish that was caught - including almost all of the LMB.

One of the most accurate statements I have seen on the subject of pond population balance in BG/LMB waters is that maintaining balance is like trying to balance on the edge of a knife blade. It can swing either way quickly and either way you get cut. There are numerous things that can start an imbalance from a temp drop to a poor plankton hatch or even to much or to little harvest.

Dave I think Swingle studied everything about fish - an enquiring mind !

Ok so it seems like it may depend on what you define as an overpopulation. Some folks really want to catch eating size Bluegill as one of their pond management goals. So for them, "overpopulation" might look like loads of forage-sized fish. On the other hand, if I only wanted to fish for LMB, that same pond might seem perfectly well balanced. Does that sound right? Am I missing something?

I just never hear anyone complaining that their Bluegill are SO overpopulated that they are harming the LMB population. It makes sense that it could happen up north where the bass grow slower; I've just never heard anyone say that they've seen it happen. I know it happens all the time with Crappie, I just never hear about it actually happening with Bluegill.

Am I wrong? Or is that sort of overpopulation really as common as overpopulation of LMB and Crappie?

It is not as common as with crappie. But stunted LMB and stunted BG are two sides of the same coin. You don't see BG stunting to the extent of no LMB reproduction very often but it does happen both north and south.

I've seen it with BG in an Ohio pond, maybe 1-1.5 acres. Enormous numbers of BG, hardly any larger than 3 or 4 inches, with no LMB that we could find. Fished it hard, but the catch never varied. Might be overpopulation of green sunfish, I was too ignorant to know the difference at the time.