The Salmon River is one of the upper branches of the Oregon or Columbia and takes its rise from various sources among a group of mountains to the northwest of the Wind River chain. It owes its name to the immense shoals of salmon which ascend it in the months of September and October. The salmon on the west side of the Rocky Mountains are, like the buffalo on the eastern plains, vast migratory supplies for the wants of man, that come and go with the seasons. As the buffalo in countless throngs find their certain way in the transient pasturage on the prairies, along the fresh banks of the rivers, and up every alley and green defile of the mountains, so the salmon at their allotted seasons, regulated by a sublime and all-seeing Providence, swarm in myriads up the great river and find their way up their main branches, and into the minutest tributary streams so as to pervade the great arid plains and to penetrate even among barren mountains. Thus wandering tribes are fed in the desert places of the wilderness, where there is no herbage for the animals of the chase, and where, but for these periodical supplies, it would be impossible for man to subsist.
The rapid currents of the rivers which run into the Pacific render the ascent of them very exhausting to the salmon. When the fish first run up the rivers, they are fat and in fine order. The struggle against impetuous streams and frequent rapids gradually renders them thin and weak, and great numbers are seen floating down the river on their backs. As the season advances and the water becomes chilled, they are flung in myriads on the shores, where the wolves and bears assemble to banquet on them. Often they rot in such quantities along the river banks as to taint the atmosphere. They are commonly from two to three feet long.
Washington Irving
The Adventures of Captain Bonneville, U.S.A., in the Rocky Mountains and the Far West, 1843