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distribution probably included portions of larger streams, such as the Green (Simon 1935), Yampa, White, Colorado, and San Juan rivers. Behnke and Zam (1976) suggested this subspecies was absent from the lower reaches of many large rivers because of summer thermal barriers. However, other subspecies of cutthroat trout have demonstrated seasonal migrations over 100 km, usually upstream in spring and downstream in autumn (Bjomn and Mallet 1964). Brown trout have moved over 35 km in late fall to habitats considered marginal in summer (Meyers et al. 1992). It is feasible to speculate that the lower reaches of the rivers within the Colorado River cutthroat trout range may have become acceptable habitat in winter as water temperatures moderated and this may partially explain the disjunct historical distribution apparent for this subspecies. Remaining populations now occur mostly in headwater streams and lakes. Young (1995) determined most lotic populations were in isolated, headwater streams with average daily flows less than 0.85 m3/s (30 cfs). Stream gradients usually exceeded 4%, and all fish were found above 2,290 m (7500 ft). Considerable research has been focused on inland cutthroat trout in general and Colorado River cutthroat trout in particular. Summaries of the life history and ecological requirements of this subspecies may be found in Behnke (1979, 1992), Behnke and Zam (1976), Young (1995), and Young et ale (1996). Further references on the Colorado River cutthroat trout and topics related to their conservation and management are included in a bibliography included in this Strategy. Without doubt, the distribution and abundance of Colorado River cutthroat trout have declined (Young 1995, Martinez 1988, Binns 1977, Behnke and Zam 1976). Behnke (1979) stated that the Colorado River cutthroat trout occupied less than 1% of its historical range. Young (1995) indicates most adfluvial stocks have been lost, though some populations have been reestablished in lakes in Rocky Mountain National Park from a population stocked in the Williamson lakes, California, in 1931 (pister 1990). These reviews were based on summaries of information contained in various agency reports. The authors, however, did not conduct range-wide population or field surveys to generate their reports. The information contained in these reports, therefore, give a general overview of the decline of the subspecies but they do not contain specific information on the subspecies' status throughout its range. Colorado River cutthroat trout have hybridized with non-native salmonids in many areas and consequent impacts to the genetic integrity of this exposure to introduced salmonids is clearly recognized as a major influence upon the status of most native cutthroat trout subspecies. Although there is still some disagreement about the role that hybridized populations should play in status determinations and conservation strategies of any species, recent clarifications of the U.S. Fish and Wildlife Service policy on this topic provide guidelines which were used in this document. These guidelines were interpreted in terms of genetic purity definitions for CRCT, which suggest that populations with genetic purity ratings ofB, B+, A- or A meet the intent of the policy and provide a practical and meaningful framework for assessing the status of the species. Populations meeting this genetic criterion are defined as conservation populations for this strategy. Colorado River cutthroat trout is designated as a special status species by Colorado, Utah and Wyoming. Prior to 1995, this fish was a Federal Category 2 candidate species, but does not occur in the candidate list proposed by the U.S. Fish and Wildlife Service in 1996 (50 CFR Part 17, 61 FR 7600). Use of categories 1,2, etc. was eliminated in this proposed rule. The Colorado River March 1999 8