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| Evaluation of Habitat Restoration for the Conservation of Cutthroat Trout |
Background:
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The distributions and abundances of native westslope and Yellowstone (Oncorhynchus clarkii lewisi and O. c. bouvieri) cutthroat trout in the Northern Rocky Mountain region have declined from historical levels, and both subspecies are considered at risk for listing under the Endangered Species Act. Efforts are currently underway to conserve these subspecies throughout the region. One important conservation strategy is that of habitat restoration and enhancement, but few studies have quantitatively assessed the responses of cutthroat trout populations following habitat restoration. In fact, few studies have described what constitutes ideal habitat for these subspecies, making restoration imprecise and unpredictable. In addition, competition and predation by non-native trout species, particularly brook trout that frequently occur in sympatry with both subspecies, is another major threat to their conservation. Interactions between brook and cutthroat trout are likely regulated by habitat condition, but little is known about these relationships.
During the first year of our study (under Phase III) WFHI researchers collected and compiled data to: (1) describe what would constitute high-quality habitat for westslope and Yellowstone cutthroat trout in central Montana, and (2) determine how habitat condition and the presence of brook trout would interact to reduce densities of cutthroat trout. In collaboration with the USDA Forest Service Rocky Mountain Station and Beaverhead-Deerlodge National Forest, researchers have compiled and edited a database with species presence data for brook and cutthroat trout throughout the range of cutthroat trout. It contains over 4,500 sites in Montana and Idaho. Another database has been compiled that consists of systematic samples collected by WFHI researchers at intervals of 1 to 3 kilometers in almost all tributaries within seven major basins in Montana. This second database includes fish abundance information (catch per unit effort) for each site and detailed habitat survey data. All information in these two databases is geo-referenced within a geographic information system (GIS), and GIS layers have been used to derive estimates of many of the physical attributes tested. ArcView and ArcGIS have been used to delineate watersheds above all sample sites where researchers have collected data to overlay other GIS layers to derive these estimates.
Under Phase IV, researchers have been evaluating past and on-going habitat restoration and enhancement projects that specifically targeted conservation of cutthroat trout. The purpose of this evaluation has been to assess whether these projects resulted in increased densities or distributions of cutthroat trout or brook trout and how these projects influenced potential interactions between these two species.
Goal and Objectives:
The goal of this project is to identify habitat conditions that will promote the continued persistence and conservation of westslope and Yellowstone cutthroat trout in the Northern Rocky Mountains through habitat restoration and enhancement projects. Specific objectives are: (1) to evaluate how habitat condition interacts with brook trout presence and abundance to affect the abundance and distribution of cutthroat trout, and (2) to evaluate the effect of presence of non-native fishes on success of cutthroat trout habitat restoration projects.
Progress to Date:
Our January 2007 progress report provided detailed appendices showing sites where we are collecting data and literature we have reviewed. Data collected during the three years of this project continues to be analyzed to add to data collected from 1993 through 2004. In early June, thermographs were placed in streams sampled in 2007, and researchers began re-sampling sites sampled during 2005 and 2006. Initial drafts reporting on results of two studies examining mechanisms by which brook trout displace cutthroat trout have been completed. One study evaluated food habits of juvenile and adult brook and cutthroat trout in two streams during the summer of 2005. The other evaluated competition between age-0 brook and cutthroat trout prior to their first winter within cage enclosures located in a stream during 2005 and 2006.
Future Activities:
Since an additional year of field data was collected in 2006, researchers elected to delay producing a final report until 2007. The final report will be prepared, and at least one portion of the report will be submitted as a manuscript to a peer-reviewed journal for publication. Researchers plan to present these findings at meetings and symposia during 2007 and 2008.
Projected Completion Date and Deliverables:
This project will be completed by December 31, 2007. To meet contractual agreements, researchers will deliver a final report and manuscript(s), a CD containing the report and manuscripts, all the raw and summarized data, and GIS maps showing all sample sites along with GIS shapefiles and metadata for the sample sites, thermograph sites, and drainage polygons. As stated above, researchers will present these results at conferences in 2007 and 2008 and will acknowledge the support of the WFHI in all reports, publications, and presentations.
Partners:
The study is being conducted in close cooperation with Montana Fish, Wildlife and Parks, the US Forest Service, the US Bureau of Land Management, and will involve local landowners.
References:
Sloat, M. R., B. B. Shepard, R. G. White, and S. Carson. 2005. Influence of stream temperature on the spatial distribution of westslope cutthroat trout growth potential within the Madison River basin, Montana. North American Journal of Fisheries Management 25: 225-237. |
Graduate
Research Assistant
Brad Shepard
Montana State University - Bozeman
Bozeman, Montana 59717 |
Principal
Investigator
Alexander V. Zale
Montana Cooperative Fishery Research Unit
Department of Ecology, Montana State University - Bozeman
Bozeman, Montana 59717 |
Faculty Consultant
Mark Taper
Montana State University - Bozeman
Bozeman, Montana 59717
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