"...smallest perch I stocked 2 years ago were 4-6 inch fish, so my thinking is these are proof of reproduction has taken
place."
The YP in your pictures that are in your hand seem to be 4-5" max if my hand is similar in size, so I would guess you've pulled off a YP spawn with some recruitment.
Regarding the GSF potentially eating all the YP fry, I think you'd have to be way overpopulated with GSF to get no recruitment from other fish species. The better cover you have for YOY, the better recruitment you'll get.
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