While the animals around Chernobyl are apparently thriving, an episode of River Monsters that I caught that focused on the fish in the waters in the area ended up saying that they're not quite right. the show is about going out and catching giant freshwater fish. It turns out that giant Wels catfish live in the cooling ponds. However, examination afterwards showed that problems like the fish being about twice as old as its size indicated it should be. So they're being stunted by something, probably by the radiation because there was lots of prey fishes in the waters. I'd go for landmines for best species preservation.