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Beavers and Salmon. Rachel Castor November 10, 2012. The Beavers. European Beaver - Castor fiber Found in Europe and Asia Unable to reproduce with C. canadensis American Beaver - Castor canadensis Found in North America Introduced into South America, become invasive

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beavers and salmon

Beavers and Salmon

Rachel Castor

November 10, 2012

the beavers
The Beavers
  • European Beaver - Castor fiber
    • Found in Europe and Asia
    • Unable to reproduce with C. canadensis
  • American Beaver - Castor canadensis
    • Found in North America
    • Introduced into South America, become invasive
  • Not the Mountain Beaver - Aplodontia rufa
american beaver castor canadensis
American Beaver: Castor canadensis
  • Second largest extant rodent species (after capybara)
  • Herbivorous (does NOT eat fish, insects, etc)
  • Clumsy on land with rear feet webbed
  • Creates its own habitat by damming running water
  • Lives in constructed lodge or in burrows on bank
eurasian beaver castor fibre
Eurasian Beaver: Castor fibre
  • Hunted to near extinction in Europe
  • Extinct in UK by 1600 AD
  • Extinct in Denmark by 1000 AD
  • 8 populations survived and were used to repopulate other European countries, where it has been used to restore wetlands.
history of beaver in n america
History of Beaver in N.America
  • Ubiquitous
    • arctic tundra to the deserts of northern Mexico
    • from the Atlantic to the Pacific Oceans.
  • Explorer David Thompson (crossed North America in 1784)
    • "this Continent...from the Atlantic to the Pacific Ocean, may be said to have been in the possession of two distinct races of Beings, Man and the Beaver."
  • Historic Population = 100 to 200 million pre- fur trade
history of beaver in n america1
History of Beaver in N.America
  • Trapped for
    • Fur - Clothing and hats
    • Castoreum musk - for perfumes and medicinal uses
  • 1630 to 1640: 80,000 beaver taken per year from the Hudson River and western New York.
  • 19th century California Fur Rush
  • Hudson Bay Company (HBC) Scorched Earth policy
  • 1826-1834 HBC took 3,000 beaver per year PNW
  • 1850 - only 438 beaver taken as population decreased
  • Nearly extinct by 1900
  • Population rebounded to an estimated 10 to 15 million
  • Originally estimated 100 to 200 million before fur trade
  • 1900 The Lacey Act
  • 1903 Roosevelt establishes first Federal Bird Reservation. Goes onto establish Wildlife Refuges, National Parks, and National Forests, protecting 230, 000,000 acres
  • 1937 The Federal Aid in Wildlife Restoration Act (Pittman-Robertson Act)
  • 1973 The Endangered Species Act State Laws governing wildlife proliferated in 1990’s
  • OR 498.002 Wildlife is state property
  • OR 498.022 Selling of wildlife & furs is prohibited
keystone species
Keystone Species
  • The beaver is a keystone species, increasing biodiversity in its territory through creation of beaver ponds and wetlands.
  • Aquatic plants colonize newly available watery habitat.
  • Insect, invertebrate, fish, mammal, and bird diversity are also expanded.
beavers and fish modern studies
Beavers and Fish: modern studies
  • Is the decline of salmonids related to the decline in beaver populations?
  • Sagehen Creek Study, CA
    • Beaver dams increase # and size of trout
  • Coldwater River Study, BC
    • Beaver ponds preferred by Coho for rearing habitat
    • Over wintering and flood protection
  • Stillaguamish River Study, WA
    • Loss of beaver ponds = 89% reduction in Coho smolt production
    • Beaver pond increase smolt production 80x > Large Woody Debris
stream flow and water quality
Stream Flow and Water Quality
  • Beaver ponds increase stream flow in dry seasons by storing run-off in rainy season.
  • Increases groundwater tables
  • Remove sediment and pollutants
  • Harmful bacteria reduced in beaver ponds
  • Increased wetland functions
beaver and trees
Beaver and Trees
  • Beavers once thought to cause deforestation.
  • Still killed and relocated for causing damage to trees
  • Forests damaged in South America where beaver are introduced, invasive species and where wetlands do not form or function as they do in the Northwest
  • Studies show beaver activity increases woody plant cover
  • Trees provide shade and woody debris necessary for salmon survival
stream restoration
Stream Restoration
  • Conservation Corps 1930’s
    • Beaver stop soil erosion in streams
    • Oregon, Washington, Wyoming, Utah
    • Each $5 beaver completed $300 of work
  • Instead of Dams
    • WA Lands Council pilot study
    • In response to DOE plan to build $10,000,000,000 worth of dams for flood control

Support structures installed along Bridge Creek to encourage increased beaver activity in the John Day River drainage of E.Oregon.

bridge creek or
Bridge Creek, OR

Typical reach without beaver activity

Reach with beaver dam activity - notice large riparian zone

estuary restoration

“Recently, beaver have been discovered living in brackish water in estuarine tidal marshes, where Chinook salmon (Oncorhynchus tshawytscha) densities were five times higher in beaver ponds than in neighboring areas.” (Mapes 2009)


Salmon Move Through Beaver Dams

  • Restrict salmon during seasonal drought
  • Trout shown to cross 14 consecutively
  • Coho jump up to 2m
  • Anadromous trout and salmon found above beaver dams
  • Downstream migration unaffected by beaver dams
modern threats to beaver
Modern Threats to Beaver
  • Trapping for International Fur Market
  • Pest Status
    • DOA Killed 100,000 beaver in past 5 years
  • Habitat Degradation
    • Excessive Grazing in arid West
  • Morgan, L. H. 1868. The American Beaver and his works. J. B. Lippincott. Rochester, NY. Available: (November 12, 2012).
  • Naiman, R. J.; C. A. Johnston, and J. C. Kelley. 1988. Alteration of North American streams by beaver. BioScience: 38:11 753–762. Available: (November 12, 2012).
  • NPS (National Parks Service). 2012. Theodore Roosevelt and conservation. Available: (November 12, 2012).
  • Oregon State Law. Available: (November 12, 2012).
  • Outwater, A. 1997. Water: A natural history. Basic Books, New York. Available: (November 12, 2012).
  • Pollock, M. M., M. Heim, D. Werner. 2003. Hydrologic and geomorphic effects of beaver dams and their influence on fishes. American Fisheries Society Symposium 37. Available: (November 12, 2012).
  • Pollock, M. M., G. R. Pess, T. J. Beechie. 2004. The importance of beaver ponds to coho salmon production in the Stillaguamish River Basin, Washington, USA". North American Journal of Fisheries Management: 749–760. Available: x (November 12, 2012).
  • Pollock, M. M, T. J. Beechie, C. E. Jordan. 2007. Geomorphic changes upstream of beaver dams in Bridge Creek, an incised stream channel in the interior Columbia River basin, eastern Oregon. Earth Surface Processes and Landforms. Available: (November 12, 2012).
  • Pollock, M.M., J.M. Wheaton, N. Bouwes, and C.E. Jordan. 2011. Working with beaver to restore salmon habitat in the Bridge Creek Intensively Monitored Watershed: Design rationale and hypotheses, Interim Report. NOAA Northwest Fisheries Science Center. Seattle, WA. Available: (November 10, 2012).
  • Rosell, F., O. Bozser, P. Collen, H. Parker. 2005. Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems". Mammal Review: 248–276. Available: (November 12, 2012).
  • Ruedemann, R.; W. J. Schoonmaker. 1938. Beaver-dams as geologic agents". Science: 88:2292 523–525. Available: (November 12, 2012).
  • Science Daily. 2008. Busy beavers can help ease drought". Science Daily. Available: (November 12, 2012).
  • Brown, R. D. 2007. The History of wildlife conservation and research in the United States – and implications for the future. North Carolina State University College of Natural Resources Paper. Raleigh, NC. Available: (November 12, 2012).
  • Demmer, R., R. L. Beschta. 2009. Recent history (1988–2004) of beaver dams along Bridge Creek in Central Oregon. Northwest Science 82 (4): 309–318. Available: doi:10.3955/0029-344X-82.4.309. (November 12, 2012)
  • DFW (Department of Fish and Wildlife). 2009. Conservation history: origins of the U.S. Fish and Wildlife Service. Available: (November 12, 2012).
  • Gard, R. 1961. Effects of beaver on trout in Sagehen Creek, California. Journal of Wildlife Management 25 (3): 221–242. Available: (November 12, 2012).
  • Groc, I. 2010. Beavers sign up to fight effects of climate change. Discover, April 2010. Available: (November 12, 2012).
  • Halley, D. J. & F. Rosell. 2003. Population and distribution of European beavers (Castor fiber). Lutra: 91–101. Available: (November 12, 2012).
  • Hays, W. J. 1871. Notes on the range of some of the animals in America at the time of arrival of the whitemen. The American Naturalist 5 (7): 25–30. Available: (November 12, 2012).
  • Hood, W. G. 2009. An Overlooked ecological web: sweetgale, beaver, salmon, and large woody debris in the Skagit River tidal marshes. Skagit River Cooperative. Available: (November 12, 2012).
  • Jahn, E., and N. Fisher. 2010. Beaver assisted restoration. Oregon Field Guide. Oregon Public Broadcasting. Available (November 10, 2012).
  • Komarov, S. 2004. Why beavers survived in the 19th Century. Innovations Report. Available: (November 11, 2012).
  • Lichatowich, J.A. 1999. Salmon without rivers: A history of the pacific salmon crisis. Island Press, Washington, D.C. 317 pgs.
  • Mapes, L. V. 2009. Scientist discovers beavers building prime salmon habitat in Skagit Delta. The Seattle Times. Available: (November 12, 2012).
  • Milishnikov, A. N. 2004. Population-genetic structure of beaver (Castor fiber L., 1758) Communities and Estimation of Effective Reproductive Size Ne of an Elementary Population. Russian Journal of Genetics: 40:7 pp772–781. Available: (November 12, 2012).
  • Sun, L., D. M Ver-Schwarze. 2003. The Beaver: Natural history of a wetlands engineer. Cornell University Press. Ithaca, NY. Available: (November 12, 2012).
  • Swales, C., D. Levings. 1989. Role of off-channel ponds in the life cycle of Coho Salmon (Oncorhynchus kisutch) and other juvenile salmonids in the Coldwater River, British Columbia". Canadian Journal Fisheries Aquatic Sciences 46: 232–242. Available: (November 12, 2012).
  • Tyrell, J. B. 1916. David Thompson\'s narrative of his explorations of Western America 1784-1812. Greenwood Press. New York. Available: (November 12, 2012).
  • Wild Earth Guardians. No date. Beavers: climate heroes. Available: . (November 12, 2012).
  • Wildlife Habitat Initiative. No date. Effect of livestock exclusion in Eastern Oregon. Available: (November 12, 2012).
  • Wright, J. P., C. G. Jones, and A. S. Flecker. 2002. An ecosystem engineer, the beaver, increases species richness at the landscape scale. Oecologia 132 (1): 96–101. Available: (November 12, 2012).
photo credits
Photo Credits
  • [A] Ramstad, Kristina. 1997. Sockeye salmon jumping over beaver dam. Lake Aleknagik, AK. Wikipedia Commons. Link
  • [B] Robertson, D. Gordon E. 2010. “Canadian Beaver (Castor canadensis). Gatineau Park, Quebec, Canada. Wikipedia Commons. Link
  • [C] Začek, Sven. 2006. European beaver (Castor fiber). Tartu County, Estonia. Wikipedia Commons. Link
  • [D] Harding, Arthur Robert. 1907. Steel Traps. A.R. Harding Publishing Co, Columbus, OH. Gutenberg Book Project. Link
  • [E] Mark, William-Mathieu. 1992. Beaver pelt, wood and twine. Canadian Museum of Civilization. Gastineau, Quebec. Link
  • [F] Wheaton, Joe. Beaver dam on Bridge Creek. Eastern Oregon. Link
  • [G] Wheaton, Joe. A series of beaver dam support structures in Bridge Creek. Eastern Oregon. Link
  • [H] Pollock, M.M., J.M. Wheaton, N. Bouwes, and C.E. Jordan. 2011. Working with Beaver to Restore Salmon Habitat in the Bridge Creek Intensively Monitored Watershed: Design Rationale and Hypotheses, Interim Report. NOAA Northwest Fisheries Science Center: Seattle, WA. Link
  • [I] Berner, Allen. 2009. The Seattle Times. Seattle, WA. Link
  • [J] Juliux. 2007. European Beaver (Castor fiber) dam. Inkūnai, Anykščiai district, Lithuania. Link
  • [K]Wild Earth Guardians. Beavers: Climate Heroes. Public Domain. Link
  • [L]Wildlife Habitat Initiative. Squaw Creek in Freemont County, WY. Freemont County, WY. Link