Why did salmon catches in the Columbia River decline after the 1880s?

The decline of salmon populations in the Columbia River following the 1880s is primarily attributed to the cumulative impact of human industrial activity and infrastructure development. While the river was historically abundant with fish, the rapid expansion of the commercial fishing industry—which saw 30 canneries operating by 1881—placed significant pressure on stocks through the use of nets, traps, and wheels.1

Over time, this decline was exacerbated by several critical environmental and structural factors:

• Dams and Infrastructure: The construction of dams created physical barriers that obstructed upstream migration and resulted in the loss of spawning grounds through inundation.12
• Water Quality: The operation of spillways led to the supersaturation of water with nitrogen, which is harmful to fish, while the loss of the river’s natural current hindered the ability of spawning fish to navigate.1
• Hatchery Impacts: The introduction of hatchery-raised fish has led to the displacement of naturally spawned populations.1
• Migration Obstacles: Power-generating equipment and turbines at dams have further impeded the safe passage of both adult and juvenile salmon.12

These combined pressures have reduced annual catches to approximately 10 percent of the record levels seen in 1883.1