From what I have read and think I understand is that if the GSF get established early they can really wreck a persons stocking plans, particularly if that individual has high expectations and goals for the fishery and GSF is not one of those goals.
Inch for inch, they basically have the same mouth size as LMB the same size.
So the problem comes in if a person already has GSF 6 inches long in the pond and he stocks his pond with new 2" long FHM, BG and RES, he just put in the perfect size fish for the GSF to eat. In such a situation if the GSF are already well established and thick, almost none of the original stocked fish might survive. Thus any fast track fish goals may be completely thwarted. With the only result some fat and sassy GSF. Then if the person has not realized the mistake and six months later puts in his LMB and the GSF have grown to a size to promptly eat them, you can see how someone with trophy LMB goals could be sorely disappointed. Even if a few of the LMB escape the GSF and produce a LMB population, with GSF as pretty much the only remaining forage fish, his LMB trophy goals have been pretty much trashed by the GSF.
So that is the danger as I see it. But there are workarounds as my thread on
100% green sungish saga shows. But the result of my old pond, while perfectly acceptable for my second pond, would be a big disappointment for anyone wanting a trophy LMB pond.
So as long as you are good with the GSF being there and understand the management requirements to overcome their large aggressive mouth (namely that any fish you subsequently stock have to be big enough the GSF can't eat them), in my opinion you can still achieve a decent general fishing pond with them as part of it. But I have only been doing this pond management stuff for 4 years, so take that information for what it is worth to you.
