An interesting aspect of steelhead biology is that, in WA at least, the time of return is rather highly related to age at smolting. Age-1 smolts return before age-2 which return before age-3. Age at smolting is controlled by stream productivity; the more productive the stream the younger the smolts. This also holds in BC. By reducing salmon escapements we reduce productivity which produces older smolts which return later.

The relationship of age to return time holds for hatchery fish too. An age-2 smolt or an age-3 which didn't migrate when planted come back later than the age-1s that boogied.

It also holds for wild fish taken into a hatchery and then released are age-1s.

The time of return can also be affected by continuously selecting for the earliest spawners but it starts with smolt age.

The BC work also showed that younger smolts were more abundant and the stream overwinter capacity was higher for fish that in the fall were smaller and growing faster.

If you want more smolts and younger smolts and earlier returning adults work on increasing in-stream productivity. This only takes care of the freshwater part of the equation and if we don't fix the marine waters too we will still be paddling around in low numbers until we flush them all away.