Event Title

A Hierarchical Examination of Bull Trout Habitat Relationships in Northeast Oregon

Presenter Information

Robert Al-Chokhachy
Phaedra E. Budy

Location

Space Dynamics Laboratory

Event Website

http://water.usu.edu/

Start Date

3-26-2004 8:45 AM

End Date

3-26-2004 9:00 AM

Description

Bull trout have declined throughout their range in response to habitat loss and fragmentation in combination with other factors. Quantification of the links between habitat needs and bull trout abundance is necessary for preventing further losses of this species and ultimately to guide restoration efforts. We are conducting a multi-system, multi-scale effort to examine the habitat use and preference of bull trout in northeast Oregon. We measured bull trout habitat use and availability independently with snorkeling and traditional habitat measurement techniques at micro and reach scales in the South Fork Walla Walla River (SFWWR). At the reach scale, bull trout density was best explained by large woody debris and the presence of O. mykiss spp., while sinuosity and percent pools appeared to be unimportant. At the microhabitat scale, bull trout strongly selected deeper water, slower bottom velocities, and cover including boulders and LWD. In contrast to other studies, bull trout in the SFWW showed no preference in substrate size, suggesting that substrate is not limiting factor and may have little influence in the SFWWR. These results highlight the need for a predictive model, which can be spatially validated across the Columbia River Basin and subsequently used to guide recovery efforts.

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Mar 26th, 8:45 AM Mar 26th, 9:00 AM

A Hierarchical Examination of Bull Trout Habitat Relationships in Northeast Oregon

Space Dynamics Laboratory

Bull trout have declined throughout their range in response to habitat loss and fragmentation in combination with other factors. Quantification of the links between habitat needs and bull trout abundance is necessary for preventing further losses of this species and ultimately to guide restoration efforts. We are conducting a multi-system, multi-scale effort to examine the habitat use and preference of bull trout in northeast Oregon. We measured bull trout habitat use and availability independently with snorkeling and traditional habitat measurement techniques at micro and reach scales in the South Fork Walla Walla River (SFWWR). At the reach scale, bull trout density was best explained by large woody debris and the presence of O. mykiss spp., while sinuosity and percent pools appeared to be unimportant. At the microhabitat scale, bull trout strongly selected deeper water, slower bottom velocities, and cover including boulders and LWD. In contrast to other studies, bull trout in the SFWW showed no preference in substrate size, suggesting that substrate is not limiting factor and may have little influence in the SFWWR. These results highlight the need for a predictive model, which can be spatially validated across the Columbia River Basin and subsequently used to guide recovery efforts.

https://digitalcommons.usu.edu/runoff/2004/AllAbstracts/33