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This study explores the effects of nutrient enhancement on salmon restoration efforts, focusing on the nutrient value of salmon carcasses and their impact on nursery lakes and rivers. It examines the benefits and potential harmful effects of increased nutrient and toxin loads.
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Harvest was depriving nursery lakes of nutrients from salmon carcasses
B.C. Salmonid Enhancement Program/Lake Enrichment Program Total sockeye returns for Barkley Sound – 1903-1994 Kim Hyatt, Pacific Biological Station
Pacific Northwest streams and rivers showing increased productivity in response to nutrient additions Berry Creek, Oregon Kalama Springs, Washington Carnation Creek, B.C. Keogh River, B.C. Nechako River, B.C.
Estimated nutrient value of salmon returning to the Columbia River Basin * Prior to 2000 change in ocean conditions Gresh et al. 2000
Juvenile salmonid density Bilby et al. 1998
8 Carcasses 7 No Carcasses 6 Average Weight (g) 5 4 3 2 Oct. Nov. Dec. Coho salmon growth Bilby et al. 1998
Carcass Analogs Lower Columbia River Fish Enhancement Group
Effectiveness monitoring of carcass placement Jul Jul Wilzbach et al. (2005): “In our experiment, the addition of salmon carcasses did not detectably affect total or age-specific salmonid biomass, density, or growth.” Aug Sep Oct Claeson et al. 2006
Potential environmental concerns Water quality Pathogen spread Toxin inputs
“There are many unresolved issues surrounding nutrient enhancement in salmon restoration, particularly in the Oregon Coast Range. Decisions about salmon restoration must balance the benefits for aquatic and terrestrial organisms with the potentially harmful effects of increased nutrient and toxin loads.” From Compton et al. (2006) Ecological and water quality consequences of nutrient addition for salmon restoration in the Pacific Northwest. Frontiers in Ecology and Environment 4(1).