When it was breached in 1931, the sockeye began to return in greater numbers. Eventually, however, eight dams would block the sockeye's path ton the ocean. The numbers of sockeye and other salmon began to plummet. By the 1980s, their numbers fell into the single digits. No one is suggesting the sockeye face serious threat from harvest, and the spawning habitat is sufficient.
Dams are the key element in their decline.
The peregrine falcon's man-made foe is gone. But salmon continue to face theirs. Ultimately, captive breeding will not be enough. The Northwest, will have to seriously address the issue of dams on the Snake River, and that means breaching.