Effects of Nutrient Enhancement on Juvenile Sockeye Salmon Growth

Document Type

Article

Journal/Book Title/Conference

Lake and Reservoir Management

Volume

9

Issue

1

Publisher

Routledge

Publication Date

1994

Keywords

effects, nutrient enhancement, juvenile, sockeye salmon, growth

First Page

140

Last Page

145

Abstract

The Snake River strain of sockeye was declared endangered in 1991 in response to the decline in the number of anadromous adults returning to nursery lakes in the Snake River watershed. These fish historically migrated over 1,400 km from the Pacific ocean to five lakes in the Sawtooth Valley of central Idaho (Redfish, Pettit, Alturas, Stanley, and Yellow Belly lakes) which served as both the spawning grounds for the returning adults and as nursery lakes for juveniles (Bjornn et al. 1968). The decline in the number of adults returning from the ocean has likely lead to decreased productivity of nursery lakes in that fewer decomposing carcasses added marine nutrients to the freshwater lakes (Krohkin 1967, and Donaldson 1967 in Kyle et al. 1993). Because whole-lake fertilization has successfully increased sockeye production in coastal Alaskan and British Columbia Lakes (Kyle et al. 1988; Stockner 1987, 1992), nutrient enhancement has been proposed as one possible management strategy for aiding in the recovery of this endagered population. This approach to sockeye management could decrease water clarity and thus the aesthetic value of the lakes to recreationists. The potential conflict in management goals suggests that for whole lake fertilization to be implemented, strong evidence that nutrient enhancement improves sockeye growth or survival should be demonstrated and weighed against the expected loss of water clarity.

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