Our experience with lake sturgeon is exactly what was said about BC Hydro.
One point that I think would be useful is that the original drafting of the legislation seems to have been focused more on terrestrial species, so the concept of critical habitat worked more effectively for something that has a nest. The fish range up and down the river, and they don't typically stay in one place, ever. But there are, as was just said, some very special circumstances that become critical, like the spawning, and that is what you would protect, very specially.