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<br /><:;:) <br />In <br />00 <br />.-l <br />(;J <br />c; <br /> <br />of the endangered fish species still requires a munber of years of effort, the SJRIP made significant progress <br />during the 7-year research period. <br /> <br />The overall goal of the SJRIP was recovering the two endangered fishes in the San Juan River Basin, and <br />the studies were aimed at determining and eliminating or diminishing the limiting factors for the fishes <br />recovery. The San Juan River was considered an important geographic component of recovery for <br />Colorado pikeminnow in the 1991 Recovery Plan for that species. Presently, the USFWS is developing <br />recovery goals for the two endangered species. It is the SJRIP's intent to provide demographically and <br />genetically viable populations of these species in the San Juan River, aiding in their recovery throughout the <br />Colorado River Basin. Demographically viable populations are self-sustaining with natural recruitment and <br />an appropriate size and age-structure. Genetically viable populations are of sufficient size that inbreeding <br />issues are not a concern. <br /> <br />The biological studies conducted during the 7 -year research period showed that, although historically found <br />in the river, razorback sucker did not presently have a San Juan River population and that the reproducing <br />Colorado pikeminnow population was comprised of about 20 adults. Small population sizes were a critical <br />factor limiting the ability of the two species to increase population size during the 7-year research period. <br />These findings prompted experimental stocking of both species to detennine iflarge-scale augmentation <br />was feasible and if habitat for the fishes various life stages was available in the river. Radio telemetry was <br />used to locate Colorado pikeminnow spawning sites and dete1111ine their seasonal habitat use, as well as <br />to detennine subadult stocked razorback sucker habitat use. At the same time, physical studies were <br />underway that included mapping habitat and detennining factors necessary to create and maintain key <br />habitats for the endangered fishes. These various studies showed that: Colorado pikeminnow spawning <br />habitat consisted of very clean cobble bars; a variety oflow-velocity habitats, such as eddies and pools, <br />were used heavily by both species most of the year; and young Colorado pikeminnow used backwaters <br />and other low-velocity habitats. The mapping studies showed that many of these key habitats were <br />uncommon to rare in the San Juan River; however the stocking studies showed that the fish found the areas <br />containing these rare habitats and were able to survive and grow. Most previous stockings of both species <br />in the Colorado River Basin were not successful. <br /> <br />The habitat studies led to developing flow recommendations that involved reoperating Navajo Dam to <br />create and maintain key habitats for the endangered and other native fishes, and that would maximize key <br />habitat availability at the correct time during the life history of each species. The key habitats not identified <br />and included in the flow recommendations were habitats for larvae of the endangered species. These <br />habitats, and limiting factors for larval endangered fishes, will be studied as the adult populations increase <br />and more larvae become available to study. <br /> <br />In addition to habitat, factors that may limit the range of the endangered fish species in the San Juan <br />River were also studied. Available habitat in the San Juan River was compressed as a result of <br />constructing Lake Powell on the lower end (54 miles inundated) and Navajo Dam on the upper end <br />(27 miles inundated), reducing the portion of river available to the fish by about 80 miles. Five <br /> <br />September 2000 <br /> <br />S-2 <br /> <br />Program Evaluation Report <br />