<br />Historical references relating to the occurrence, distribution, and abundance were used to provide
<br />a historical perspective to existing status and distribution. While primarily qualitative, the historical
<br />observations provided information on trout habitat occurrence and good stream and riparian habitat
<br />condition. I assumed that 25% of the intermittent stream miles were historically once perennial waters
<br />which have been altered by anthropogenic activities (UDWR 1991). Similarly, I assumed that up to
<br />90% of most perennial waters historically contained BCT populations. Historical records cited provide
<br />reference to trout occurrence in most perennial waters containing suitable habitat, from headwaters
<br />to low-elevation reaches. Many waters once tributary to lake Bonneville still provide perennial stream
<br />habitat, with seasonal use of some intermittent reaches, as stream channels dip and meander below
<br />higher terraces of the ancient lake (Hubbs and Miller 1948).
<br />
<br />Information for mapping and stream mileage by sub-basin, both perennial and intermittent, was
<br />obtained from the U.S. Geological Survey and Utah Automated Geographic Reference Center geo-
<br />graphic information system (GIS) data. Maps of the Bonneville basin and individual national forest
<br />maps were also used to validate stream miles and population location. State and federal resource
<br />data bases, where available, were also used.
<br />
<br />CURRENT STATUS
<br />
<br />The BCT In the Bonneville Basin Is considered a unique subspecies of western cutthroat trout.
<br />Previous status reports have identified the need to protect its remaining populations and habitats by
<br />state and federal management agencies throughout its range. The American Fisheries Society (AFS),
<br />in 1979, listed BCT as 'hreatened' throughout its range due to continuing degradation of habitat and
<br />hybridization with exotic (non-native) species. The U.S. Fish and Wildlife Service (FWS), in 1980, the
<br />FWS announced a status review of the BCT. In 1982, the FWS identified the BCT as a Category II
<br />candidate species (47 FR 58454, December 30,1982). The FWS, in 1985, re-classified the BCT as
<br />a Category I candidate species (50 FR 37958, September 18, 1985). The AFS, in 1989, re-classified
<br />BCT as 'endangered'. The FWS, in 1994, listed the BCT as a declining candidate species, Category
<br />II (59FR 58982, November 15, 1994). In 1996, under revised priorities for listings, the FWS has
<br />discontinued their Categorical status, and only those species previously identified as Category I are
<br />now considered candidate species. The BCT therefore, is not a candidate species at this time, but
<br />the FWS remains concerned about BCT status and encourages further research and study to resolve
<br />its conservation status. Utah considers the BCT a species of special concern (S1 status) and has
<br />considered it within a conceptual management plan for all cutthroat trout in Utah (Schmidt et al.
<br />1995). Also, in 1995, Utah formed a interagency conservation team for the BCT and has developed
<br />a draft conservation agreement and strategy plan for its recovery (UDWR 1996). In addition, similar
<br />ongoing conservation strategy efforts are being undertaken in Nevada, Idaho, and Wyoming for BCT.
<br />Figure 1 illustrates the historic range of the Bonneville cutthroat trout.
<br />
<br />This assessment reports current status and recent investigations, primarily on national forest system
<br />(NFS) lands by state and federal biologists. This assessment identifies 67 pure populations occupy-
<br />ing habitats on NFS lands, including four lakes, in 15 major sub-basins, two are located outside the
<br />Bonneville Basin (Figures 2 and 3). The following occurrence of these populations on NFS lands, by
<br />state, is: Utah 48%, Wyoming 33%, Idaho 13%, and Nevada 6%. In addition, there are 15 populations
<br />occupying an estimated thirty-four stream miles which may be classified as 'suspect' pure BCT, but
<br />additional genetic validation is necessary to clarify the uncertainty in lineage. This concern for
<br />determination of genetic status is most prevalent in the Bear River sub-basins where the native
<br />cutthroat trout (BRB) shares a close-relatedness to the Yellowstone cutthroat trout from ancestral
<br />invasions into the Bonneville basin and Lake Bonneville (Behnke 1992; Shiozawa and Evans 1994,
<br />Behnke and ProbsteI1995).
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