We do have a large number of turtles and many different species. What is the impact- positive or negative- of the turtles in the lake?
Turtles are an interesting topic. Most species are omnivores. Eat plants and animals. Larger species, like alligator snapping turtles, are carnivores. So even red-eared sliders eat fish. Generally speaking, if a turtle catches a fish, that fish needs to come out of the population anyway. It is probably old or diseased, or wounded. I don’t think I’ve ever seen a scenario where the turtle population has seriously damaged a fishery but never say never.
I’ve always viewed it as a pond or lake having a carrying capacity for all species, including turtles. Once that carrying capacity is reached, the population tends to stabilize. Now how has Vilbig reached the carrying capacity for turtles? Probably not. Also, things like removal or relocation are generally reasonably tricky. Because the turtles ultimately came from somewhere, and as you remove some, others typically fill in the gaps.
Like carp and gar, I have always viewed them as part of the overall ecosystem.