Your distribution map for GS was created from old data sets. My Atlas of North American Freshwater Fishes (1980) shows your map as the Former Distribution; Present distribution of GS includes all of NY except the northern upper third of the state.

Hopefully your sunfish are pumpkinseeds. They will be a lot less of a fish management problem than GS. Try to catch one of the males guarding the nest and get a close-up photo. I will try to identify the fish just from a photo. If you drag a rake through the sunfish nests every few (4-6) days you will prevent a lot of the eggs from hatching.

Do your best to try and locate some fingerling SMB for stocking this fall. Have you checked with Zetts Fish Hatchery in Drifting PA? They send fish air freight. SMB will help control this years sunfish that have hatched.

You will need to get yourself some various sizes of fish traps for help with fish monitoring, thinning and management. Hopefully Pond Boss magazine will have an article before next spring about building homemade fish traps. Several styles of fish traps are available for purchase on the internet and in fish supply stores. Longer (20-50 ft) minnow seines ($25-$100) pulled through the shallows and or beach areas will catch a lot of small fish.

aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management