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<br />001587 <br /> <br />requires a number of years of effort, the SJRIP made significant progress during the 7-yearresearch <br />period. <br /> <br />The overall goal of the SJRIP was recovering the two endangered fishes in the San Juan River <br />Basin, and the studies were aimed at determining and eliminating or diminishing the limiting <br />factors for the fishes recovery. The San Juan River was considered an important geographic <br />component of recovery for Colorado pikeminnow in the 1991 Recovery Plan for that ~",ecies. <br />Presently, the USFWS is developing recovery goals for the two endangered species. h is the <br />~ SJRIP's intent to provide demographically and genetically viable populations of these species in <br />~ the San Juan River, aiding in their recovery throughout the Colorado River Basin. <br />\ Demographically viable populations are self-sustaining with natural recruitment and an appropriate <br />j size and age-structure. Genetically viable populations are of sufficient size that inbreeding issues <br />I <br />are not a concern. <br /> <br />The biological studies conducted during the 7-year research period showed that, although <br />historically found in the river, razorback sucker did not presently have a San Juan River population <br />and that the reproducing Colorado pikeminnow population was comprised of about 20 adults. <br />Small population sizes were a critical factor limiting the ability of the two species to increase <br />population size during the 7 -year research period. These findings prompted experimental stocking <br />of both species to determine iflarge-scale augmentation was feasible and if habitat for the fishes <br />various life stages was available in the river. Radio telemetry was used to locate Colorado <br />pikeminnow spawning sites and determine their seasonal habitat use, as well as to determine <br />sub adult stocked razorback sucker habitat use. At the same time, physical studies were underway <br />that included mapping habitat and determining factors necessary to create and maintain key habitats <br />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 <br />pools, were used heavily by both species most ofthe year; and young Colorado pikeminnow used <br />backwaters and other low-velocity habitats. The mapping studies showed that many of these key <br />habitats were uncommon to rare in the San Juan River; however the stocking studies showed that <br />the fish found the areas containing these rare habitats and were able to survive and grow. Most <br />previous stockings of both species in the Colorado River Basin were not successful. <br /> <br />The habitat studies led to developing flow recommendations that involved reoperating Navajo Dam <br />to create and maintain key habitats for the endangered and other native fishes, and that would <br />maximize key habitat availability at the correct time during the life history of each species. The <br />key habitats not identified and included in the flow recommendations were habitats for larvae of <br />the endangered species. These habitats, and limiting factors for larval endangered fishes, will be <br />studied as the adult populations increase 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 <br />Juan River were also studied. Available habitat in the San Juan River was compressed as a result <br />of constructing Lake Powell on the lower end (54 miles inundated) and Navajo Dam on the upper <br />end (27 miles inundated), reducing the portion ofriver available to the fish by about 80 miles. Five <br /> <br />September 2000 <br /> <br />8-2 <br /> <br />Program Evaluation Report <br />