The other aspect of steelhead life history that is ignored for the most part is that they repeat spawn. Not because it is fun but because they evolved that way and need it to survive.

The complete data I have seen (rack counts, ages for all adults) hardly ever show a steelhead R/S even equal to 1 for survival to first spawning. Have seen one set that is >1 when the repeats are added to brood-year production and this analysis discounts the fact that most repeats are female and more fecund than virgins.

You get higher R/S when smolt age is lower, which may partially explain why hatchery programs were generally successful with the "salmon model" of spawn once.

I understand that some some runs in AK and Kamchatka have repeat proportions of 50-90% of the run. The R/S on virgins can't be very high.

As Salmon notes, this whole thing is way more complex and teasing out the answers will take lots of time and money. A steelhead broodyear may not have all the virgins back for six years. Which means that when you start a study that requires trapping, age analysis, and such that it takes six years for one complete data point. How many agencies have the institutional commitment to fund and operate a program for 15-20 years just to get basic information?