> Of course there are blues in a system of lakes in western Quebec< >It's not that they have trouble believing that it could happen, in fact, I'm sure that the icthyologists believe that that is EXACTLY what did happen. However, they recognize that the two varieties were effectively isolated by the falls which established separate gene pools and the possibility for genetic divergence. < What's the argument against reintroducing an extinct species, where humans' pollution is the cause for the extinction, based on a unprovable assumption that there MAY be genetic drift from the original species? I could see if the original species had some number still present. Or if the reason for extinction were natural. Something WILL fill the empty niche left be the original. It would seem preferable to me that it be a variant of the original species rather than a different species, especially if non-native species. In general, I believe it's futile to try to tinker with "mother Nature." The interconnectivity of environment is way too complex for us to try to engineer a better one. But I can see some merit in trying to repair or the damage that's been done in this example. I'm not being adversarial, I would like to understand the reasoning better. Bill Vannerson http://ourworld.compuserve.com/homepages/william_vannerson