Department of Ecology
Montana State University
AJM Johnson Hall
Bozeman, MT 59717
B.S. Biology, Southern Oregon University
- Landscape Fish Ecology
- Fish/Habitat Relationships
- Disturbance & Climate Change Role in Fisheries Conservation
M.S. In progress. Landscape-scale effects of wildfire on the Colorado River cutthroat trout in the headwaters of the Colorado River, Colorado.
The distribution and abundance of Colorado River cutthroat trout Oncorhynchus clarkii pleuriticus have declined from historical levels over their entire range and it is estimated that 13% of the historically occupied habitat is currently occupied. This study is focused on the native Colorado River cutthroat trout in the headwaters of the Colorado River, an area that where the risk of wildfire has increased significantly because of the widespread infestation of the mountain bark beetle.
Gathering prefire information on the distribution, abundance, and population structure of the Colorado River cutthroat trout assemblages and the aquatic habitat and upslope condition is critical for the predicting the effects of wildfire or other disturbances on the remaining populations. These factors are especially relevant where periodic disturbances are extensive, and effects are not uniform, spatially or temporally, across the landscape. Moreover, relationships between habitat and Colorado River cutthroat trout are not well documented at the watershed scale, and information concerning distribution, abundance, and population structure will be useful for documenting current conditions to assess future changes related to restoration activities, wildfire, and climate change.
To provide information necessary to evaluate the effects of wildfire at the landscape scale, data concerning physical and biological characteristics of study watersheds will be used for a spatial assessment of the vulnerability of a high elevation landscape to negative consequences of fire. In order to address questions concerning the vulnerability of Colorado River cutthroat trout populations in the headwaters of the Colorado River, we are collaborating with the other US Geological Survey researchers to evaluate the potential risk of fire and postfire consequences to stream habitat and Colorado River cutthroat trout populations in Grand County, Colorado.
Specific objectives include: (1) Evaluate the risk of wildfire in watersheds in the study area (Grand County). (2) Identify watersheds where significant postfire floods, debris flows, and sediment deposition that could negative effects on aquatic resources. (3) Using information obtained from Objectives (1) and (2), we will assess the current distribution of Colorado River cutthroat trout and nonnative salmonids in randomly selected watersheds in the headwaters of the Colorado River and evaluate the relationship between stream habitat characteristics and distribution, abundance, and population structure of stream salmonids.
By sampling all pools in each catchment, it is possible to develop a spatially explicit representation of trout abundance in the channel network. This approach provides the biological and geographical information to examine the spatial structure of cutthroat trout abundance among study catchments. The spatial extent and fine-scale detail will provide data necessary to examine structure of cutthroat trout assemblages with geostatistical techniques in stream networks and investigate the influence of the physical habitat template on the patterns of trout abundance and population structure at a variety of spatial scales.
Data analyses will be conducted hierarchically at three spatial scales (watershed scale, within watershed, disturbed-control comparisons). Watershed-scale analysis provides the most information about the distribution of fishes prior to disturbances such as fire. Baseline information on predisturbance habitat conditions and spatial patterns of aquatic biota will provide a basis for future comparisons. The second level of analysis will explore watersheds in individual watershed classes (defined by susceptibility to erosion and debris flow in the initial stream classification). A third level of analysis will be conducted in the event of wildfire in the study area. If fire occurs, we will differentiate patterns of fish relative abundance in treatment and control (burned-unburned) watersheds. Geographic analysis spatial patterns in fish distribution will focus on the identification of geomorphically distinct peaks in fish distribution.