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Bony tail (Gila elegans) Adultbonytail, large members of the minnow family (cyprinidae), may reach up to 22 inches total length and weigh up to 2.4 pounds. An unknown nwnber of wild adults exist in Lake Mohave on the mainstem Lower Colorado River (i.e" downstream from Glen Canyon Dam), and there are small nwnbers of wild individuals in the Green River and Colorado River subbasins ofthe Upper Colorado River Basin (Figure 5). Historically, bonytail were common to abundant from Mexico to Wyoming in warm-water reaches of larger rivers in the Colorado River Basin. Little is known about its specific habitat requirements, because the bonytail was extirpated from most of its historic range prior to extensive fishery surveys. It is considered to be adapted to mainstem rivers where it has been observed in pools and eddies. Similar to other closely related Gila species, bonytail probably spawn in rivers in spring over rocky substrates; spawning has been observed in reservoirs over rocky shoals and shorelines. Based on available distribution data, flooded bottomland habitats probably are important for bonytail growth and conditioning, particularly as nursery habitats for young. TIrreats to the species include stream flow regulation, habitat modification, predation by introduced nonnative fish species, hybridization, and pesticides and other pollutants (USFWS 2002b). Only 11 wild adults have been reported recently from the Upper Basin (Valdez et a1. 1994). Bonytail were transferred from Lake Mohave to hatcheries to develop broodstock for artificial propagation and subsequent release of progeny into several locations in Upper and Lower basins (Hamman 1981, 1982, 1985). Roughly 130,000 hatchery-produced bonytaiI were rei eased into Lake Mohave between 1981 and 1987 as part of an effort by the Service to prevent the extinction of the species and promote its eventual recovery. However, survival of bonytail stocked into riverine reaches has been low (Chart and Cranney 1991), and no recruitment or reproduction of stocked fish has been docwnented to date. Nevertheless, the bonytaiI is so severely depleted in the wild that management actions to prevent its extinction must take priority. Self-sustaining populations need to be established through augmentation (USFWS 2002b). In Colorado, 5,000 fingerling bonytail were stocked in the Green River above Lodore Canyon and 5,000 were stocked in the Yampa River at Echo Park in July 2000 by the Colorado Division of Wildlife (CDOW). In March 2001, CDOW stocked 13,000 fingerling bonytaiI in the Green River. Pursuant to Section 4(b )(2) ofthe ESA, on March 21, 1994 (59 FR 13374) the Service designated critical habitat for the bonytail within its historic range, including the Yampa River from the boundary ofDNM in T.6N., R.99W., section 27 (6th Principal Meridian) to the confluence with the Green River in T.7N., R.103W., section 28 (6th Principal Meridian). Self-sustaining populations ofbonytail are not known to occur in the Yampa River at this time. However, such populations had occurred in both the Yampa and Green rivers in the past. Recovery goals for the bonytail prescribe 15 management actions needed for recovery, of which the following 10 actions are applicable to the Yampa/Green River complex: 1. Re-establish populations with hatchery-produced fish. 2, Provide and legally protect habitat (including flow regimes necessary to restore and maintain required environmental conditions) necessary to provide adequate habitat and sufficient range for all life stages to support recovered populations. 3. Investigate habitat requirements for all life stages and provide those habitats. 4. Ensure adequate protection from overutilization. Management Plan for Endangered Fishes in the Yampa River Basin 14