1. Ecological role of anadromous salmon in aquatic ecosystems: A literature survey on the nutrient inputs in Pacific salmon habitats Janice Liang ‘16 Environmental Studies, Colby College Case Study: Washington State Problem: Salmon population on decline in Washington Evidence of nutrient deficit The low productivity of streams in the Pacific Northwest means that no other nutrient sources are available to compensate for declining returns of adult salmon Solution: Hatchery carcasses placed in streams Tethered or anchored in place (natural anchors or biodegradable tethers used if possible) In SW WA, marine-derived nitrogen in the muscle tissue of juvenile salmonids increased as much as 39% following carcass placement Analogs (dried, processed hatchery salmon) are another alternative Background: Pacific salmon are anadromous and semalparous 3 ways salmon contribute to the nutrient subsidy in aquatic ecosystems: Live salmon excretions Eggs Salmon carcasses Salmon-nutrient inputs can: Impact stream productivity Increase phytoplankton and zooplankton availability Increase juvenile salmon populations Important because salmon populations are currently on the decline Dams in particular impede migration and block nutrients in the sediment to flow to spawning grounds Conclusion: From a conservation standpoint, analogs and hatchery carcasses are a good, temporary fix to salmon population declines Abundant use of these alternate nutrient inputs could stimulate nutrient subsidies and population growth in areas of low nutrients and salmon populations Alternative option to salmon carcasses going to landfill; using nutrients in practical and effective way Until we can adequately target larger problems, like the removal of dams that are blocking salmon runs, artificial nutrient inputs are necessary to compensate for the nutrients from salmon that do not make it back to their spawning grounds Uncertainties: These solutions are not very well-understood Some research supports the use of analogs and hatchery carcasses, but only as temporary fixes Other research has shown live salmon nutrient inputs (excretions and eggs) being more beneficial in stream productivity than analogs Discrepancies among habitats; more research needs to be done for more focused results References: Bilby, R., B. Fransen, P. Bisson, and J. Walter. 1998. Response of juvenile coho salmon and steelhead to the addition of salmon carcasses to two streams in southwestern Washington, U.S.A. Canadian Journal of Fisheries and Aquatic Sciences 55: 1909-1918. Cascade Columbia Fisheries Enhancement Group. 2014. Nutrient Placement Feasibility Study. http://www.ccfeg.org/completed-projects/ studies-and-assessments/nutrient/. Accessed April 2014. FishEx Quality Seafoods. 2014. The Fasciniating Life of an Alaskan Salmon. http://www.fishex.com/seafood/salmon/salmon-life-cycles.html. Accessed April 2014. Gende, S., R. Edwards, M. Wilson, and M. Wipfli. Salmon in aquatic and terrestrial ecosystems. BioScience 52: 917-928. Gresh, T., J. Lichatowich, and P. Schoonmaker. 2011. An estimation of historic and current levels of salmon production in the Northeast Pacific ecosystem: Evidence of a nutrient deficit in the freshwater systems of the Pacific Northwest. Fisheries 25: 15-21. Kohler, A., T. Pearsons, J. Zendt, M. Mesa, C. Johnson, and P. Connolly. 2013. Nutrient enrichment with salmon carcass analogs in the Columbia River basin, USA: A stream food web analysis. Transactions of the American Fisheries Society 141: 802-824. Levy, S. Pacific salmon bring it all back home: Even in death, these fish fuel life in their natal streams. 1997. BioScience 47: 657-660. Miller, K. 2002. North American Pacific Salmon: A case of fragile cooperation. FAO Fisheries Report 695: 105-122. Schindler, D., M. Scheuerell, J. Moore, S. Gende, T. Francis, and W. Palen. 2003. Pacific salmon and the ecology of coastal ecosystems. Frontiers in Ecology and the Environment 1: 31-37. Ties, S., P, Levi, J. Ruegg, D. Chaloner, J. Tank, and G. Lamberti. 2011. Ecological effects of live salmon exceed those of carcasses during an annual spawning migration. Ecosytems 14: 598-614. Washington Department of Fish & Wildlife. 2013. Salmon Hatcheries Overview. http://wdfw.wa.gov/hatcheries/overview.html. Accessed April 2014.