Many BOWs I fish have Gams and here are a few thoughts. As has already been mentioned, they should only be stocked where they are common and native to your watershed. In this case, however, it may be hard to keep them out.
They are native here and whether they were stocked in these BOWs I do not know. What I can say is that there are a few BOWs where I have not observed them. In these cases, they may have been extirpated but I my general sense is that they have never been there. Shoreline shallows seem to provide just enough cover to protect a breeding population. In BOWs that have GAMs I notice much better condition of BG and a higher frequency of small LMB. From my posts, you will notice that I like to fly fish for large bluegill and so I tend to focus on fishing ponds which have GAMs ... that is unless ... I am fishing for bait for bass and catfish. LMB though capable of growing to 2 lbs in one year, infrequently outweigh BG after their first summer in a mature pond. O year bass and bluegill compete directly for resources and O year bluegill quickly outgrow the gape of 0 year LMB. The presence of GAMs can alter that scenario by providing a
type of forage that the O year LMB can more effectively utilize than the O year BG. O year LMB growth is benefitted in the presence of GAMs.
Potential Problems for trophy LMB:
1. GAMs prefer the same foods that 0 year BG prefer and compete for these resources. They tend to be predators that do not convert primary algal production to forage. In this sense they will inhibit BG reproduction, help BG outgrow the gape of predators for the same reason and as a source of forage. Because of this, GAMs make BG less available as forage for LMB.
2. The presence of GAMs reduces BG competition with 0 year LMB and provide forage that O year LMB are better at capturing. Increased survival of young LMB (1-2 years) hamper growth of larger LMB by two influences. They reduce BG survival and help BG grow more quickly (individually). So the surviving BG are more capable of escaping predation.
For trophy LMB, it would seem that prey items which can utilize primary algal production are better choices as they do not directly inhibit BG reproduction. PK shrimp are examples of such forage. Ultimately, cover, weeds, and brush are necessary to establish breeding populations of the kinds of things which will assist in the production of BG forage. Minnows of any kind, though very good for young bass may not help with the goal of trophy LMB. If one the other hand one is interested in the production of eating size LMB, then they would be a good introduction that helps with early growth and recruitment.
Benefits for Trophy Bluegill:
1. Gams help LMB recruitment and directly compete with YOY BG reducing BG survival and boosting surviving BG growth as forage.
2. Gams have been shown to increase pond production
(
Swingle). But keep in mind this was in the absence of other possible forage choices.
Whether I would stock GAMs in a trophy BG pond might depend on whether I also had a small forage pond in which I could grow FHM. Though FHM would be unable to reproduce in the trophy BG pond, a small forage pond might provide a significant amount of fry to stock the main pond. Clearly, FHM's utilization of primary production would increase both BG and LMB forage. The question might then be whether increased BG survival (over GAMs)would present challenges for larger BG.
All in all, for bigger BG and LMB recruitment, GAMs appear to be very beneficial at least from my observations.