Cooperative Research Units
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Abundance and Impact of predators on sockeye salmon in Lake Washington


September 2014 - June 2015


The Lake Washington fishery for sockeye salmon is an important recreational fishery in a large urban lake alongside Seattle. The fishery has been closed since 2006 due to insufficient spawning escapement by returning adult sockeye. Currently 94% to 99% of juvenile sockeye that enter the lake as do not survive to the presmolt stage in Lake Washington one year later. Previous studies have shown that predation by Cutthroat trout and Northern Pikeminnow could conceivably account for nearly all of the lake-phase mortality of juvenile sockeye, depending on the abundance and size structure of the predator populations in the lake. In addition, the populations of juvenile salmon and alternative prey (Longfin Smelt and Threespine Sticklebacks) potentially influence the variability in seasonal and annual predation mortality imposed on juvenile Sockeye Salmon.
In order to properly assess the predatory impacts of coastal cutthroat trout and northern pikeminnow on juvenile Sockeye Salmon the study will accomplish the following two objectives: 1) estimate the abundance of previously identified important predators of juvenile sockeye in the lake (coastal cutthroat trout and northern pikeminnow), and to 2) quantify their predation on juvenile sockeye.


Current Staff

Federal Staff: 95

Masters Students: 239

Phd Students: 142

Post Docs: 53

University Staff: 240

5 Year Summary

Students graduated: 701

Scientific Publications: 1936

Presentations: 4260



Funding Agencies

  • Washington Department of Fish and Wildlife


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey