I still think cloning is a great Idea. At least collect the samples now.

As far as habitat goes, fish need it yes, but besides the loss of it (I.E DAMS) I dont believe Its one of the main contributing factors in the decline of the salmon and steelhead. I have silvers running in a small ditch along the road and the water is anything but clean and there is not the right size gravel in it Yet fish run it every year. There is also a simular case in silverdale a city creek that barely runs year round (its a trickle in the summer) it gets plenty of fish.