SS1.07 Ecological Links to Population Dynamics and Productivity of Salmon
Date: Friday, June 14, 2002
Time: 11:15:00 AM
Location: Lecture Theatre
 
EdmundsonJA, Alaska Department of Fish and Game, Soldotna, USA, jim_edmundson@fishgame.state.ak.us
Mazumder, A, , University of Victoria, Victoria, Canada, mazumder@uvic.ca
 
ARE NUTRIENTS FROM SALMON CARCASSES IMPORTANT IN SUSTAINING PRODUCTIVITY?
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Increasingly, biologists and resource managers are recognizing that anadromous Pacific salmon, which die after spawning, transport large quantities of marine-derived nutrients (MDN) into freshwater through migration to their natal spawning grounds. Dispersion of MDN is assumed vital to the productivity, biodiversity, and overall ecosystem health of Pacific Northwest watersheds. However, little attempt has been made to synthesize the effects of consumers, species interactions, and trophic dynamics in this new context. Current research on salmon carcasses and MDN in aquatic ecosystems has shifted away from considering the “top-down” effects of consumers and mainly emphasized “bottom-up” effects of MDN on the biomass of different trophic levels. We examined the potential contribution of MDN to the production of sockeye salmon using a variety of data on trophic dynamics of Alaskan lakes. We suggest that if sockeye salmon carcasses provide strong bottom-up trophic level benefits to other salmonids, there will be a measurable loss of yield associated with high spawner densities and lower fry recruitment due to variable nutrient-foodweb dynamics within and among lakes. This kind of resource trade-off will pose major challenges for fishery managers.