If you only think on a watershed basis. Back when we were marking steelhead (100% of the smolts, 100% of the adults, 100% of the kelts) we got relatively few marked adults back to the trap and NO marked repeat spawners even though we had repeats annually. It appeared that the small-stream steelhead aren't really tied to just that stream. Same observation from BC.

This, at least up until a few years ago, was supported by genetic studies that showed not a whole lot of differentiation among watersheds.

If so, the long term survival of steelhead might be dependent on keeping good numbers in all the streams and not just select a few favorites.