Date of Award
Master of Science (MS) in Biology
A. Ross Black
This study determined which kokanee stock performed best in Lake Roosevelt, WA: Lake Whatcom, Meadow Creek, or F1 mixed stock. The F1 mixed stock was created by collecting eggs from Lake Whatcom, Meadow Creek and non-marked kokanee that returned to Hawk Creek and raising them to the residualized smolt stage at the Spokane Tribal hatchery for release back into Lake Roosevelt. Fall spawning run data (2009 – 2012) were analyzed to assess the percentage and sex ratios of each stock returning to spawn in Lake Roosevelt. We had record returns of hatchery kokanee in 2009 (n = 8,895) and 2010 (n = 8,925), but poor returns in 2011 (n = 423) and 2012 (n = 1,893). The F1 mixed stock significantly outperformed the Lake Whatcom and Meadow Creek stocks for both return percentage (P <0.001) and sex ratios (P <0.001) in each year. The record kokanee returns of 2009 and 2010 coincided with relatively shallow drawdown and longer water retention times, whereas, the poor 2011 and 2012 returns coincided with a deep drawdown and shorter water retention times.
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Blake, Alix O., "Assessment of the hatchery kokanee (Oncorhynchus nerka) release program in Lake Roosevelt 2009 -- 2012" (2013). EWU Masters Thesis Collection. Paper 131.