Date of Award
Master of Science (MS) in Biology
"White sturgeon (Acipenser transmontanus) in the upper Columbia River have been in decline for over 60 years and are listed as critically endangered by the International Union for Conservation of Nature. Annual spawning produces dispersing larvae; however, recruitment into the juvenile age class has not occurred since the early 1970s. One hypothesis to explain this failure in recruitment is that larvae may not find adequate prey. Little is known about diet and prey availability for white sturgeon larvae, especially in Lake Roosevelt, a reservoir of the Columbia River. The Spokane Tribe of Indians collected littoral and mid-channel benthic drift samples annually at 9 locations in Lake Roosevelt from 2007 to 2010. Zooplankton dominated drift samples in both littoral and thalweg zones, while excluding zooplankton, Hydra dominated the drift. Overall, the mean density and biomass of invertebrates within the flow was highest in littoral sites and highest in years with the greatest flow. Littoral and thalweg sites had no impact on drifting benthic macroinvertebrate diversity, richness, or evenness. To determine the feeding ecology, 590 larvae were collected in July 2015. A total of 14 prey items were found in 9 stomachs, mainly Dipteran larvae and Temoridae. Our results suggest that prey scarcity could be limiting white sturgeon recruitment in Lake Roosevelt"--Leaf 4.
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Reihart, Ryan W., "Invertebrate drift in the upper Columbia River with implications for young-of-the-year white sturgeon" (2016). EWU Masters Thesis Collection. 403.