Pre-Run Temperature Monitoring
A number of people have asked me, "Why all the fuss about stream temperatures early in the run?" Well, putting all of the technical literature aside regarding initial upstream migration temp thresholds, the following historical raw return numbers vs. stream temperatures illustrate part of the the point pretty well. What you are looking at in other words are the numbers of steelhead which returned to trap at a particular temperature range: ~5-8 degree spread. And I apologize, I don't recall specifically how many years of return data are represented here, but it's over 3000 fish sampled, so I would call that a pretty good data-set. For those of you who have been following along for a while now, "Magic 40" and all that...