Of course that would not be smart to say that dams are the only thing responsible for the decline of anadromous fish species. but it can and has been proven undeniably that they are a piece of the puzzle. they provide prime habitat for warmwater species that eat salmon and steelhead fry and smolt, in many cases they prove to be an impassable barrier to returning fish.

yes, yes I know it has been shown in studies that many fish do make the out migration through the turbines and and many fish survive the ride down the spillway but even after that they make tasty treats for pikeminnows and birds after they become disorientated and temporarely incompasitated
due to water turbulence and hyper-oxegonation.

Bottom line is they are not good at all for the native anadromous fish so why even start to defend them.

of course I do enjoy the electricity they produce but I would rather have fish.