Thats all fair, and in a perfect world that would make sense. My point in the great lakes is that with species like the alewife, elimination could lead to a total collapse in parts of the foodchain. Sure, given enough time its possible that the lakes could recover to resemble what they were before we messed things up, but at what cost in the meantime? In michigan, if the food chain brakes down and and the salmon fishery goes away, so goes all of the funding for other DNR projects. Also, even if we had the will to carry out eradication on that level, what is the initial financial cost to do so? We don't even have the resources to effectively combat sea lamprey, how can we possibly fix all of the other problems? I'm not saying we shouldn't always be searching for ways to help the ecosystem, but we must do so in ways that we can realistically help and not just wast money.