Yes, the problem is pretty much the same as the Herschel debacle, but with many more players (Harbor seals, Sea Lions, gulls, terns, cormorants, diving ducks of various species, river otters, and other fish) involved Anytime there is a "choke point", either natural or man-made, predators gather to take advantage of the easy pickings. I agree with you that this fact should not come as a surprise. In this case however, I don't think the option of killing all of the predators on the smolts (including other salmon/steelhead) is going to be embraced by anyone. One aspect of the problem, same as happened on Lake Washington, is that the population of the fish you want to protect is low enough that if nothing is done, you may lose the species.