To survive, there are two things a salmon needs. To eat. And to not be eaten.
Dave Bitts, a fisherman based in Eureka, California, as quoted in this morning's New York Times story: West Coast Enigma as Salmon Vanish Without a Trace, which recounts how the Chinook simply aren't running in California waters this year. And nobody's entirely sure why.
If you were a West Coast Salish, or Haida, or a member of another Pacific tribe, who welcomed the salmon each Spring as a sign of the world's renewal, something like this would pretty indicate that the whole thing was winding down. As in the end of the world as we know it.
And an aside: I worked for a Norwegian immigrant and octogenarian a long time ago as his amanuensis, helping him compile his stories as a Bering Sea fisherman and Pacific Northwest logger and Seattle longshoreman in anticipation of a book. One of his stories was about the running of the salmon in the Pacific Northwest, and how the rivers teamed so fiercely when the salmon ran in the Spring that it was if they were boiling and the horses started in fear.
Those are the rivers that are quiet now.