It's netting sturgeon that kills them in great numbers. In the '90 s a friend of mine who was a gillnetter told me that the gillnetters on the lower Columbia in the fall were changing out the mesh size on their nets to target sturgeon. The "bycatch" was worth many times more than the coho fishery that they were carrying out. Nets were being set in the shallows where the sturgeon were known to be. My friend didn't fish the Columbia but had a place in Chinook as well as Bothell and he knew what was going on down there. He told me that that would be the end of the sturgeon because of the "bycatch" policy that our own WDFW was going with. Obviously my friend thought this was a wrong-headed policy. At the time our family had just begun to sport fish for sturgeon out of Chinook and the sturgeon were easy to catch and like others have mentioned hard to kill. I doubt very much that catch and release is harming the population much if any.