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Westslope cutthroat trout 2002 status assessment
(Contains Shepard et al. (2003) report, supporting data, and GIS files)
|Dates of Data
||2002 TO 2002
|Data Set Status
|Data Set Update Schedule
||Approximately every 5 years.
|Date Data Set Published on StreamNet Data Store
|Project Name & Number
|Purpose of Data Set
||Purpose provided in Abstract
|Summary / Abstract
||The distribution and abundance of westslope cutthroat trout (Oncorhynchus clarki lewisi; WCT) have declined from historical levels over part or all of their historical range. For the U.S. range of WCT we used existing information provided by 112 fisheries professionals applied through a consistent methodology to assess the extent of WCT historical range, their current distribution, including genetic status, and evaluated the foreseeable risks to 539 populations designated as conservation populations by management agencies.
We estimated that WCT historically occupied about 56,500 miles of habitat within the U.S. WCT currently occupy an estimated 33,500 miles of historically occupied habitats (59%). Genetic testing has been completed across about 6,100 miles of habitat (18% of occupied habitats), but sample sizes were variable and sample sizes of 25 fish or more (a sample size that likely would detect as little as 1% levels of introgression with a 95% level of confidence) made up 30% of the samples. WCT with no evidence of genetic introgression currently occupied about 3,400 miles (10%) of currently occupied habitats. Another 1,000 miles of currently occupied habitats (3%) contained WCT that were probably part of a mixed stock where the WCT were not introgressed. We suggest that even though genetic sampling was nonrandom because sampling likely occurred more frequently in WCT populations that appeared non-introgressed, some, if not much, of the habitats currently occupied by WCT where no genetic testing has been done likely support populations that are not introgressed. Much of the habitat currently occupied by WCT was located in designated parks (2%), wilderness areas (19%), and roadless areas (40%), and almost 70% of habitats currently occupied lie within federally managed lands.
A total of 563 separate WCT populations currently occupying 24,450 miles of habitat were designated as conservation populations. These conservation populations were spread throughout the historical range, occuring in 67 of the 70 hydrologic units historically occupied by WCT. Most of these conservation populations were believed to be .isolets. (457 or 81%); however, metapopulations occupied much more of the habitat (21,600 miles or 88%). Of the 563 designated conservation populations, 339 (60%) had at least some component that was genetically unaltered and 172 (30%) consisted entirely of stream segments that were genetically unaltered. For the 539 conservation populations for which risks to the population were asseessed, more isolet populations were at higher risks due to temporal variability, population size, and isolation than metapopulations, but these isolets were generally at less risk from genetic and disease factors than metapopulations.
This assessment clearly shows that WCT currently occupy significant portions of, and are well distributed across, their historical range. The data suggest that genetically unaltered WCT occupy at least 13% and possibly up to 35% of currently occupied habitats (8 to 20% of historical habitats). Conservation population designations suggest that two different conservation management strategies are needed and being implemented to conserve WCT. One strategy concentrates on preventing introgression, disease and competition risks through isolation of WCT, while the other concentrates on preserving metapopulation function and multiple life- history strategies by connecting occupied habitats.
|Broad Biological Groups
||Westslope cutthroat trout (Oncorhynchus lewisii clarki)
||Montana, Idaho, Wyoming, Washington, Oregon
|NPCC Subbasins (2001 Subbasins)
||Outside the Columbia basin: Outside Columbia Basin
Blue Mountain: Asotin
Blue Mountain: Grande Ronde
Blue Mountain: Imnaha
Blue Mountain: Snake Hells Canyon
Columbia Cascade: Lake Chelan
Columbia Cascade: Methow
Columbia Plateau: John Day
Columbia Plateau: Palouse
Columbia Plateau: Snake lower
Intermountain: Coeur d'Alene
Intermountain: Pend Oreille
Middle Snake: Snake lower middle
Mountain Columbia: Bitterroot
Mountain Columbia: Blackfoot
Mountain Columbia: Clark Fork
Mountain Columbia: Flathead
Mountain Columbia: Kootenai
Mountain Snake: Clearwater
Mountain Snake: Salmon
||genetics introgression miles historical distribution barriers risks land management impacts range
|Lead Person and Organization That Created the Data Set
|Other Participating Organizations
||Montana Fish, Wildlife & Parks (MFWP)
Montana Cooperative Fishery Research Unit
USDA Forest Service (USFS)
Idaho Department of Fish and Game (IDFG)
Oregon Department of Fish and Wildlife (ODFW)
Washington Department of Fish and Wildlife (WDFW)
|Contact Person for Questions About the Data
||Name: Dawn Anderson
Position: Fisheries Database Manager
Organization: Montana Fish, Wildlife & Parks
Address: Montana Fish, Wildlife & Parks, Fisheries Division
PO Box 200701
1420 E. Sixth Avenue
email: Send a note to mt.gov addressed for dawanderson.
|Broad Category of Methods
|Data Collection Methods
||Various. Original field data were collected using various methods. Data in this data set were compiled from available data.
||Adobe Acrobat (.pdf)
Hypertext markup language (html)
Microsoft Access 2000 (.mdb)
Shape file (.shp, .shx, .dbf)
Microsoft Word (.doc)
|Data structure description
||See data set files
|URL where updated data may be available
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|Relationship between the data set and the software, model, etc.
|Where the software, tools, models, etc. can be obtained if they are not included with the data download.
|Contact person for questions about the software, tools, models, etc.
|Papers, reports, and presentations that were done under this project.
||Shepard, B.B, B.E. May, W. Urie, C. Corsi, K. McDonald, R. Snyder, T. Unterwegner, J. Uehara, and K. Walker. 2003. Status of westslope cutthroat trout (Oncorhynchus clarki lewisi) in the United States: 2002.
|Restrictions or legal prerequisites for accessing and using this data set.