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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 - PowerPoint PPT Presentation

Text of Beavers and Salmon

  • Beavers and SalmonRachel CastorNovember 10, 2012

  • The BeaversEuropean Beaver - Castor fiberFound in Europe and AsiaUnable to reproduce with C. canadensisAmerican Beaver - Castor canadensisFound in North AmericaIntroduced into South America, become invasiveNot the Mountain Beaver - Aplodontia rufa

  • American Beaver: Castor canadensisSecond largest extant rodent species (after capybara)Herbivorous (does NOT eat fish, insects, etc)Clumsy on land with rear feet webbedCreates its own habitat by damming running waterLives in constructed lodge or in burrows on bank

  • Eurasian Beaver: Castor fibreHunted to near extinction in EuropeExtinct in UK by 1600 ADExtinct in Denmark by 1000 AD8 populations survived and were used to repopulate other European countries, where it has been used to restore wetlands.

  • History of Beaver in N.AmericaUbiquitousarctic 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.AmericaTrapped forFur - Clothing and hatsCastoreum musk - for perfumes and medicinal uses1630 to 1640: 80,000 beaver taken per year from the Hudson River and western New York. 19th century California Fur RushHudson Bay Company (HBC) Scorched Earth policy1826-1834 HBC took 3,000 beaver per year PNW1850 - only 438 beaver taken as population decreasedNearly extinct by 1900

  • ProtectionPopulation rebounded to an estimated 10 to 15 millionOriginally estimated 100 to 200 million before fur trade 1900 The Lacey Act1903 Roosevelt establishes first Federal Bird Reservation. Goes onto establish Wildlife Refuges, National Parks, and National Forests, protecting 230, 000,000 acres1937 The Federal Aid in Wildlife Restoration Act (Pittman-Robertson Act) 1973 The Endangered Species Act State Laws governing wildlife proliferated in 1990sOR 498.002 Wildlife is state propertyOR 498.022 Selling of wildlife & furs is prohibited

  • Keystone SpeciesThe 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 studiesIs the decline of salmonids related to the decline in beaver populations?Sagehen Creek Study, CABeaver dams increase # and size of troutColdwater River Study, BCBeaver ponds preferred by Coho for rearing habitatOver wintering and flood protectionStillaguamish River Study, WALoss of beaver ponds = 89% reduction in Coho smolt productionBeaver pond increase smolt production 80x > Large Woody Debris

  • Stream Flow and Water QualityBeaver ponds increase stream flow in dry seasons by storing run-off in rainy season.Increases groundwater tablesRemove sediment and pollutantsHarmful bacteria reduced in beaver pondsIncreased wetland functions

  • Beaver and TreesBeavers once thought to cause deforestation.Still killed and relocated for causing damage to treesForests damaged in South America where beaver are introduced, invasive species and where wetlands do not form or function as they do in the NorthwestStudies show beaver activity increases woody plant coverTrees provide shade and woody debris necessary for salmon survival

  • Stream Restoration

    Conservation Corps 1930sBeaver stop soil erosion in streamsOregon, Washington, Wyoming, UtahEach $5 beaver completed $300 of work

    Instead of DamsWA Lands Council pilot studyIn 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, ORTypical reach without beaver activityReach with beaver dam activity - notice large riparian zone

  • ESTUARY RESTORATIONRecently, 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)

  • Do Dams Block Salmonids?

  • Restrict salmon during seasonal droughtTrout shown to cross 14 consecutivelyCoho jump up to 2mAnadromous trout and salmon found above beaver damsDownstream migration unaffected by beaver dams

    Salmon Move Through Beaver Dams

  • Modern Threats to BeaverTrapping for International Fur MarketPest StatusDOA Killed 100,000 beaver in past 5 yearsHabitat DegradationExcessive Grazing in arid West

  • Overgrazing :cause of beaver and salmon declines

  • SourcesMorgan, 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 753762. 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: 749760. 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: 248276. Available: (November 12, 2012).Ruedemann, R.; W. J. Schoonmaker. 1938. Beaver-dams as geologic agents". Science: 88:2292 523525. Available: (November 12, 2012).Science Daily. 2008. Busy beavers can help ease drought". Science Daily. Available: (November 12, 2012).

  • SourcesBrown, 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 (19882004) of beaver dams along Bridge Creek in Central Oregon. Northwest Science 82 (4): 309318. 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): 221242. 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: 91101. 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): 2530. 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:

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