Event Title

Exploring Relationships Between Channel Gradient, Gravel Availability, and Brown Trout (Salmo trutta) Spawning Densities in Logan River, Utah

Presenter Information

Christy Meredith
Phaedra Budy

Location

Eccles Conference Center

Event Website

http://water.usu.edu/htm/conference/past-spring-runoff-conferences

Start Date

2-4-2009 9:05 AM

End Date

2-4-2009 9:10 AM

Description

A need exists to better identify mechanisms contributing to altitudinal species zonation of brown trout (Salmo trutta) versus native species. Although brown trout help augment fishing opportunities throughout much of their introduced range, expansion into higher elevations due to climate change or anthropogenic alterations could be deleterious to conservation of key populations including Bonneville cutthroat trout. Previous research suggests that distribution of spawning gravels may limit brown trout distributions because of the species' small home range. In this study, we explored relationships between gravel availability, slope, and spawning densities of brown trout along an altitudinal gradient in the Logan River, Utah. Ground-truthed slope estimates were obtained via satellite GPS and compared to slopes estimated from the National Hydrography Dataset (NHD) and derived stream layers, in concert with DEMs. Redd densities were correlated with gravel availability (r2=0.83) and also with stream slope (r2 = 0.632). However, slope was not a good predictor of gravel availability in all reaches (r2 = 0.169). Use of the DEM versus field data over-predicted stream slope in almost every reach, except high gradient reaches with limited canyon or tree cover (r2= 0.453). Further sampling and model development are needed to better explore these relationships. Gravel availability may be an important limitation at low-elevations, but not at high elevations, where temperature-related factors or other factors related to slope may dominate. In this context, the use of Digital Elevation Models has great potential, but their limited accuracy may affect predictive ability.

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Apr 2nd, 9:05 AM Apr 2nd, 9:10 AM

Exploring Relationships Between Channel Gradient, Gravel Availability, and Brown Trout (Salmo trutta) Spawning Densities in Logan River, Utah

Eccles Conference Center

A need exists to better identify mechanisms contributing to altitudinal species zonation of brown trout (Salmo trutta) versus native species. Although brown trout help augment fishing opportunities throughout much of their introduced range, expansion into higher elevations due to climate change or anthropogenic alterations could be deleterious to conservation of key populations including Bonneville cutthroat trout. Previous research suggests that distribution of spawning gravels may limit brown trout distributions because of the species' small home range. In this study, we explored relationships between gravel availability, slope, and spawning densities of brown trout along an altitudinal gradient in the Logan River, Utah. Ground-truthed slope estimates were obtained via satellite GPS and compared to slopes estimated from the National Hydrography Dataset (NHD) and derived stream layers, in concert with DEMs. Redd densities were correlated with gravel availability (r2=0.83) and also with stream slope (r2 = 0.632). However, slope was not a good predictor of gravel availability in all reaches (r2 = 0.169). Use of the DEM versus field data over-predicted stream slope in almost every reach, except high gradient reaches with limited canyon or tree cover (r2= 0.453). Further sampling and model development are needed to better explore these relationships. Gravel availability may be an important limitation at low-elevations, but not at high elevations, where temperature-related factors or other factors related to slope may dominate. In this context, the use of Digital Elevation Models has great potential, but their limited accuracy may affect predictive ability.

http://digitalcommons.usu.edu/runoff/2009/AllPosters/24