Some really juicy stuff, Parker. To add to one of your points, I've read studies that latitude of river system has effects on % repeat spawners in a given population as well. For example, some rivers in the northern Great Lakes region might have repeat rates approaching 35%. Similar trends (but less in magnitude) have been mentioned in the PacNW as well, but I can't remember which study I found that.

O mykiss is an interesting critter regardless of how you approach him.