CogKnoSys

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Physical

Columbia River Salmon Runs

Columbia River salmon runs are the yearly journeys of salmon from the Pacific Ocean up the Columbia and its tributaries to spawn where they hatched.

↓ Specific: nothing more specific yet

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The idea

A salmon run is a yearly migration in which salmon swim from the ocean back up rivers to spawn on the gravel beds of small creeks. Salmon are anadromous. They hatch in fresh water, swim out to sea, where they spend their adult lives and gain most of their weight, and then return upstream to breed. They usually come back to the river where they were born, and even to the exact spawning ground. At sea they are thought to find their home river by sensing Earth's magnetic field. Near the river, they use smell to find the right stream.

The Columbia River system hosts many species of anadromous fish that travel between fresh water and the salty Pacific Ocean. These fish, especially salmon, were the main food of native peoples. The Columbia and its streams have been central to the region's culture and economy for thousands of years. Most salmon species migrate during the autumn, from September through November.

After spawning, all species of Pacific salmon die. Their bodies bring nitrogen, phosphorus and other ocean nutrients to inland streams, wetlands and riverside woods. These nutrients feed living things from tiny invertebrates to bears. In Northwest America, salmon are keystone species, which means their effect on other wildlife is greater than their biomass alone would suggest. A salmon run is also a major feeding event for predators such as grizzly bears and bald eagles.

Check yourself

Question 1 of 3

In 2007, the removal of which dam became the first dam removal in the Columbia River system?

Pick one. The first pick counts.

Composition

what it's made of

  • Spawning grounds — Gravel beds in small creeks in the upper reaches of rivers, where salmon lay their eggs.
  • Young salmon — Juveniles that hatch in fresh water and spend their early life in rivers or lakes.
  • Ocean years — The adult stage at sea, when salmon gain most of their body mass.
  • Homing — The return trip to the home river, guided at sea by magnetoreception and near the river by smell.
  • Carcass nutrients — Nitrogen, sulfur, carbon and phosphorus from dead salmon that feed riverside plants and animals.

Connection

how it relates

Under Lower Columbia Ecosystems and Wildlife

Related

  1. Bonneville Damstrength 70 of 100

    Dams on the Columbia, such as Bonneville, have become barriers that salmon must get past to reach their spawning grounds.

  2. Columbia River Gorgestrength 50 of 100

    Celilo Falls, at the eastern end of the gorge, was a major salmon fishing site for Native Americans until dams submerged it.

  3. Multnomah Peoplestrength 40 of 100

    Salmon was one of the main foods of the Multnomah, a Chinookan people of the lower Columbia.

Cause and effect

  1. Food Chainsstrength 60 of 100

    Salmon carry ocean nutrients inland, feeding bears, eagles, small invertebrates and the plants along rivers.

Change

how and why it evolves

Past
Salmon fed native peoples along the Columbia long before outsiders arrived. Since the early 20th century, dams have been built across the river for power, navigation, irrigation and flood control, and they have become barriers to fish migration. In 2007, the removal of Marmot Dam on the Sandy River became the first dam removal in the Columbia system.
Now
Chief Joseph Dam has no fish ladders, so it completely blocks fish migration to the upper half of the Columbia River system. With the river slowed by dams into a chain of slackwater pools, young salmon take much longer to reach the sea, and more of them die on the way.
Next
Efforts to help salmon get past dams and to restore spawning streams will probably shape how large future runs can be.

Knowledge you can walk. Read the idea, then step up, across or down.

Columbia River Salmon Runs

Columbia River salmon runs are the yearly journeys of salmon from the Pacific Ocean up the Columbia and its tributaries to spawn where they hatched.

Learn, discuss, create, buy or invest

The idea

A salmon run is a yearly migration in which salmon swim from the ocean back up rivers to spawn on the gravel beds of small creeks. Salmon are anadromous. They hatch in fresh water, swim out to sea, where they spend their adult lives and gain most of their weight, and then return upstream to breed. They usually come back to the river where they were born, and even to the exact spawning ground. At sea they are thought to find their home river by sensing Earth's magnetic field. Near the river, they use smell to find the right stream.

The Columbia River system hosts many species of anadromous fish that travel between fresh water and the salty Pacific Ocean. These fish, especially salmon, were the main food of native peoples. The Columbia and its streams have been central to the region's culture and economy for thousands of years. Most salmon species migrate during the autumn, from September through November.

After spawning, all species of Pacific salmon die. Their bodies bring nitrogen, phosphorus and other ocean nutrients to inland streams, wetlands and riverside woods. These nutrients feed living things from tiny invertebrates to bears. In Northwest America, salmon are keystone species, which means their effect on other wildlife is greater than their biomass alone would suggest. A salmon run is also a major feeding event for predators such as grizzly bears and bald eagles.

Check yourself

3 quick questions, instant feedback.