salmon decline

Umpqua Watershed, Oregon, USA

* The Singing Falls Stream Restoration Project *

Factors Responsible for the decline in Salmon abundance and distribution in the Pacific Northwest

The numbers after each category relate to the list at the bottom of the page.

MAJOR FACTORS

Agriculture: 1, 2, 4, 5, 6, 8, 9, 10, 18, 21, 22

Fishing: 16, 19

Dams: 9, 11, 18

Forestry: 1, 2, 4, 6, 7, 10, 21, 22

Drought: 9, 10

Urbanization: 1, 3, 5, 6, 7, 8, 9, 10, 11, 21, 22

*POTENTIALLY IMPORTANT FACTORS **

Gravel Harvest: 6

Irrigation: 9, 12

Bycatch Mortality: 16, 19 (salmon killed during fishing for other species)

Hatchery Fish Interference: 19, 20

Poor Ocean Conditions: 13, 14, 15, 16

Illegal Fishing: 16, 19

MINOR FACTORS

Bird Predation: 17

Marine Mammal Predation: 16, 17

Components Of The Factors Causing Salmon Decline

1. Loss of Streamside Vegetation and Functions

2. Pesticide Exposure

3. Industrial Pollutants Exposure

4. Increased Amount Of Sediment Entering Streams

5. Stream Straightening and Channelizing

6. Habitat Destruction

7. Decreased Amount Of Large Logs In Streams And Loss of Deep Pools and Channel Form

8. Filling of The Side Channels of Streams

9. Reduced Fresh Water Flow In Rivers and Streams

10. Exposure to Abnormal Temperatures

11. Habitat Area Loss

12. Lack of Screening of Water Diversion Canals to Keep Fish Out

13. Reduced Upwelling

14. Altered Ocean Currents and Flow

15. Decreased Food Abundance

16. Reduced Numbers of Adults Reaching Their Spawning Grounds

17. Reduced Numbers of Young Fish Making It To The Sea

18. Barriers Preventing Salmon From Migrating Upstream or Downstream

19. Loss of Genetic Integrity and Diversity

20. Competition Between Hatchery and Wild Fish

21. Forest Fragmentation

22. Estuary Degradation

* Insufficient data exists for an appropriate assessment of magnitude.

Table based on studies of rivers in Western Oregon and Northern California. Adapted with permission by Pacific States Marine Fisheries Commission from Status and Future of Salmon of Western Oregon and Northern California: Overview of Findings and Options by Botkin, Cummins, Dunne, Regier, Simpson, Sobel, and Talbot. For a copy send $17 to The Center for the Study of the Environment, P.O. Box 6945, Santa Barbara, CA 93160.