I recently read an article in a fishing magazine in a doctors office, I do not remember the name of the magazine. Tha article stated that opposed to the common belief (scientific/public) that steelhead evolved from rainbow trout that they are actually in no way related. They commpared this to the long beleif of Dolly Varden and Bull trout being the same fish, which was recently discovered that they are not. It said that Bull trout are a mimic (sp) of Dolly Varden that evolved withen the last 8,000 years, and a 4,000 years before that you would not have recognised the fish. Anyway, back to the point. It said that rainbow and steelhead do not share the same parent spiecies, but that the steelhead made its presence only around 19,000 tears ago and they have not yet determind what it evolved from. But they were possitive it was not the Rainbow. Something about sea levels and comming out of an ice age and location and a bunch of stuff about DNA. I have no idea how correct the Stealhead info is, but the Dolly/Bull info is pretty much scientific common knowledge now, even though the full story has not yet spread to all anglers. I have read several articles on that subject and when the info was just starting to surface my highschool marine biology class went over it.