Salmon in 1938: Bonneville Dam · 597

Anadromous fishes that move ocean fat onto spawning gravels -- and into forests, treaties and hydropower fights. Most Oncorhynchus (Pacific) are semelparous. Salmo salar can spawn more than once. The postcard of corpses on gravel is a Pacific-weighted image. Isotope studies show marine nitrogen in riparian trees and songbirds. Bears and eagles are the visible vectors; the trees keep the receipt.

What did the Elwha dam removals show? After 2011-14, sediment flushed and salmon recolonised reaches above the old dams faster than some models feared -- a rare full-height teardown. Are hatcheries a solution or a delay? They keep harvest numbers up and can dilute wild fitness. The argument is now about proportions, not existence.

Why are Atlantic salmon a different politics? Wild S. salar collapsed in much of Europe and New England. Farmed Atlantic salmon in net pens are a separate industry with sea-louse and escape files. Many Alaska runs are still large and limited-entry managed. That success is not transferable to a heavily dammed Columbia without the same habitat.