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File Size: 240 MB

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Yellowstone cutthroat trout 2006 status assessment (Contains May et al. (2006) report, supporting data, and GIS files.)

Data Categories Distribution - Current and Historic
Conservation Populations
Expansion populations
Dates of Data 2006 TO 2006
Data Set Status Complete
Data Set Update Schedule Approximately every 5 years.
Date Data Set Published on StreamNet Data Store 10/27/2008
Project Name & Number
Purpose of Data Set Purpose provided in Abstract
Summary / Abstract The distribution and abundance of Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri; YCT) has changed substantially from the historical conditions that existed when European 'discovery' of the western portion of North America occurred in the early 1800's. Factors associated with these changes have been linked to anthropogenic influences that accompanied early settlement of the west. In recent years, there have been numerous efforts to describe the changes that have occurred. Early status assessments for YCT described the changes in general, qualitative terms; however, few assessments applied a quantitative approach that could be replicated through time. A detailed description of the changes in the assessment methods through time can be found in Appendix A.

This (2006) status assessment represents the second iteration of an assessment approach designed to provide comparable information through time. Thirty-two fisheries professionals who had personal knowledge of YCT within the assessment area provided the information for this status assessment. These biologists served as representatives of 10 agencies and they had a combined level of professional experience of 480 years, of which 365 years were directly applicable to YCT conservation and management. Information associated with YCT was obtained through application of a consistent methodology that was developed specifically to provide information pertinent to cutthroat trout conservation. This status assessment used the National Hydrography Dataset (NHD), at the 1:24,000 map scale, coupled with geographic information system (GIS) tools and personal geo-database compatible with ArcGIS 9.0 as the base foundation for the status assessment. Fourth level hydrologic units (HUC) were used as accounting units for data storage and retrieval. YCT information for the status assessment was obtained during two workshops where groups of biologists (Appendix B) and data entry personnel completed the questions contained in the status protocol (Appendix C) and the information was entered into a geodatabase. The status assessment also evaluated foreseeable population risks linked to disease and the maintenance of genetic integrity. A general population health evaluation was also completed for each conservation population of YCT.

Historical habitat for YCT was estimated to include 17,721 miles of stream and 61 lakes. These historical habitat estimates represented a refinement of historical estimates obtained in 2001 (i.e., 17,393 miles; 118 lakes). The estimate of currently occupied (conservation and sportfishing populations) habitat was 7,527 miles (43%) of historical habitat. The number of lakes currently occupied by YCT was estimated to be 205. The amount of stream habitat with genetic testing data increased to 4,052 miles (a 34% increase). Results showed that a substantial number of YCT occur in a genetically unaltered condition. In addition, there were another 1,854 miles of stream that were classified as untested and suspected to be unaltered based on the absence of hybridizing fish in close proximity to the YCT. Most YCT represent aboriginal populations and most occupied habitat is judged to be in excellent (14%) and good (52%) condition. Slightly more than one half of stream dwelling YCT co-existed with non-native fish. YCT densities were mostly in the 1- to 151-fish/mile density range. Much of the habitat currently occupied by YCT (65%) was located within federal jurisdictions or under the authority of tribal governments (e.g., Forest Service, National Park Service, the Crow Tribe, etc.). Eleven hundred and forty six miles were administered as wilderness.

A total of 383 separate YCT conservation populations (7,204 miles) were identified in the 2006 status assessment. This number was almost 100% higher than the number of populations identified in 2001. YCT conservation populations occurred in 35 of the 39 historical watersheds. Two hundred and sixty one (261) YCT populations were associated with only stream environments, 45 populations were associated with habitat that was composed of both stream and lake environments, and 76 YCT populations were associated with only lake environments. Many populations occupied less than 1 mile of stream habitat. Population numbers were variable and ranged from a few fish to nearly 100,000 fish. An evaluation of risk to genetic integrity indicated that populations occupying smaller less complex habitats were less likely to be at risk from hybridization. The majority of populations occupied less than 10 miles of habitat. These population were, however, much more likely to have smaller population sizes, reduced temporal variability and more apt to have simple habitat networks (e.g., non-networks or weak networks). The converse of these conditions was evident for populations occupying larger units of habitat. These populations tended to have higher population numbers and they occupied larger habitat networks resulting in higher temporal variability scores. These populations tended to be at higher risk to compromised genetic integrity. The risk of disease was judged as being minimal to low for most YCT populations regardless what other conditions prevailed.

Evaluation of restoration and expansion opportunities indicated that some options were potentially available. An appraisal of restoration or expansion potential for 6,970 miles of suitable habitat was completed as a component of the status assessment. The analysis indicated that between 15 to 40 % of the suitable habitat provided a reasonable opportunity for population restoration or expansion.

The 2006 status assessment substantiated that genetically unaltered YCT currently occupy significant portions of the historical habitat. Even though YCT tend to have a higher presence within the central core of the range, they do exist within many watersheds on the perimeter of the historical range. Data on conservation populations suggest that two different conservation strategies are reflected in the characterizations associated with the populations. One strategy is associated with reduced risks to genetic integrity and competition from non-native species, but the approach is also associated with lower population health conditions due to lower temporal variability and population size. The other strategy is associated with larger populations that occupied more diverse habitat networks. These larger populations have higher health scores associated with temporal variables and larger population size, but they reflect a greater risk to genetic integrity. Most populations were identified as having a minimal or low risk from disease.
Broad Biological Groups Fishes
Taxa Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri)
Location Yellowstone Cutthroat Trout range.
Idaho, Montana, Wyoming, Utah, Nevada
NPCC Subbasins (2001 Subbasins) Outside Columbia Basin
Keywords Yellowstone Cutthroat Trout, Assessment, Historic distribution, Current distribution, Conservation populations
Lead Person and Organization That Created the Data Set Dawn Anderson
Other Participating Organizations Wild Trout Enterprises, LLC
SEAM Biometrics, LLC
Montana Fish, Wildlife & Parks
Wyoming Game and Fish Department
Idaho Department of Fish and Game
Utah Division of Wildlife
Nevada Division of Wildlife
USDA Forest Service
USDI Fish and Wildlife Service
National Park Service
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
Helena, MT  59601
Phone:  406-444-3373
email:  Send a note to addressed for dawanderson.
Broad Category of Methods Field
Data Collection Methods Various. Original field data were collected using various methods. Data in this data set were compiled from available data.
File Formats Adobe PDF
Microsoft Access 2000 database
ArcMap shapefiles .shp
Data structure description See data set files
URL where updated data may be available
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File Size: 240 MB