While I won't belittle the ocean mortality issue I think a bigger one is that steelhead have very poor R/S for survival to first time spawners, I have never seen a compete data set (count escapement, age for all adults) where the R/S even averaged 1.0. Repeat s[pawners are required.

That means that any steelhead killed on their first return fisheries are also not returning in subsequent years.

Data from both BC and WA showed that as the smolt age lowers you get a better R/S. The =1.0 is about at a mean smolt age of 1.5. To get age 1 smolts, as BC showed, you need the nutrients in the streams. They did it with fertilizers and then pinks. You also got more smolts when the smolts are younger. Finally, the experiments showed that they got sustainable returns in the fertilized stream even in years of poor ocean survival in neighboring streams.

This data has been around for 30 years or more; but since the easiest solution to nutrient delivery is spawning salmon it is DOA.