Wild steelhead, as Jerry said, returned 12 months of the year.
Wild steelhead used to spawn at least January-July, and maybe even wider
In places where they are abundant, wild steelhead have 50-80+% repeat spawners instead of next to nothing.
Wild steelhead, in PS, used to have significant numbers of age-1 smolts. Canadian research has shown that the same river produces numerically more smolts if they are age-1 than if age-2 and more smolts if they are age-2 than if age-3, and so on.

We have taken a fish that had a successful life history pattern and removed all the parts we found inconvenient. Kill off the earlies so we can catch chum and hatchery steelies, kill off the lates so we can fish springers, kill off the repeat spawners so we can kill them this year, and so on.

Stelhead are just too inconvenient to have around; they make management way too difficult.