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Unfortunately, many Yellowstone cutthroat trout populations, currently exist as localized remnants (Table 13) of original sub-populations with little or no connectivity. Others owe their existence to hatchery programs. Current estimates indicate that Yellowstone cutthroat occupy 41 % of historic riverine environments throughout the historic range. In addition, there are about 450 lake environ- ments, within the historic range, that currently support Yellowstone cutthroat trout. The number of lake environments currently supporting Yellowstone cutthroat populations represents a 380% in- crease over historic levels. Additionally, there are now numerous riverine and lake populations in existence outside of the historic range (Hadley 1984; Varley and Gresswell 1988) resulting from extensive stocking. Caution should be applied before developing conclusions relative to overall Yellowstone cutthroat status. With the exception of populations in Montana, most populations have not received sufficient testing for a definitive assessment of genetic status (Table 14). Based on the findings in Montana, genetic contamination is probable for most cutthroat populations that have been exposed to rainbow trout or cutthroat of hatchery origin. As pointed out in this assessment and others previously cited, fragmentation and population isolation has occurred as a result of stream dewatering, replacement by introduced non-native fish, hybridization, substantial environmental change, and overharvest. Many populations find themselves in a form of ecological "catch 22". Most owe their current existence to passage barriers, whether natural or man-made, which have effectively controlled access of both contaminating and competitive species which are present in nearly all areas of the current range (Table 15). At the same time these populations find themselves restricted to relatively small "patches" of habitat that have, in many cases, been degraded by human activity. Viability concerns increase with decreasing "patch" size, declining habitat quality, and complexity, and increased isolation from "source" populations. Aquatic environments inhabited with Yellowstone cutthroat trout on National Forest lands tend to be in better condition and support more populations. Present estimates indicate that 63% of historic riverine habitats on National Forests still support populations of Yellowstone cutthroat. Most of the currently occupied lake habitats are found on National Forest administered lands. Because of limited genetic testing, caution should be used before development of final conclusions relative to current status within the National Forests. As more definitive genetic information becomes available, it is likely that fewer genetically pure populations will actually exist on the National Forests. MANAGEMENT CONSIDERATIONS The long-term well-being of Yellowstone cutthroat trout will require a comprehensive and well coordi- nated conservation approach. A shared vision of goals and objectives between agencies and individuals that have legal responsibilities and vested interests will be essential to long term success. An on-going effort to develop a management guide for Yellowstone cutthroat trout within the Yellow- stone River basin should be a management catalyst for developing the shared vision of responsible agencies and individuals. The "Management Guide" recommends goals for providing protection, maintenance and restoration within the historic range of Yellowstone cutthroat trout. The Manage- ment Guide is equally applicable to the Snake River portion of the historic range. Principle compo- nents associated with the management guide and specific application based on findings of this assessment include the following: 23