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<br />(~") <br />c-, <br />~ <br /><..C <br />(:) <br />Q::l <br /> <br />I ,000 large juveniles in the river by 1999. This success, along with genetic concerns for the existing, small <br />wild population, delayed development of an augmentation plan for this species. The success in using <br />stocked fish to augment the two endangered species populations in the San Juan River is a major <br />accomplishment of the SJRIP. <br /> <br />A Draft Long Term Monitoring Plan was developed and implemented in 1999, and finalized in 2000. This <br />plan provides for: native fish community monitoring, including larvae, young, and adults; physical-feature <br />monitoring related to key habitat maintenance; and continued evaluation of the flow recommendations, <br /> <br />DETERMINE THE ROLE(S) OF NONNATIVE FISH SPECIES IN THE <br />DECLINE OF NATIVE FISH SPECIES AND IMPLEMENT <br />CORRECTIVE ACTIONS <br /> <br />Concurrent with studies of the native fish community, the nonnative fish community was also intensively <br />studied, These studies included density estimates, habitat-use studies, food habit analyses, competition <br />studies, and studies of flow effects on population levels. Channel catfish and common carp were the <br />second and fourth most-commonly collected fish species in the San Juan River, respectively. Red shiner <br />and fathead minnow were the most-common fish in low-velocity habitats, Although food habit studies did <br />not show high levels of predation on native fishes, the sheer abundance of channel catfish makes it likely <br />that even low levels of predation may impact the native fish community. Red shiner was also implicated <br />as a potential predator ofIarval native fishes in other Upper Basin rivers, and its abundance in the San Juan <br />River suggests it also may be a predator of concem, Because of the low population levels of the two <br />endangered fishes, impacts to these species from nonnative interactions were difficult to document. Young <br />Colorado pikeminnow, red shiner, and fathead minnow used the same habitats and ate the same foods, but <br />good growth and survival of stocked Colorado pikeminnow suggested that they were not limited by <br />competition from nonnative species. <br /> <br />Altered flows from Navajo Dam did not reduce numbers of nonnative fishes, and channel catfish and <br />common carp increased in density during the 7-year research period. Preliminary information suggested <br />red shiner was temporarily reduced by mid- to late-sununer flow spikes caused by thunderstorms, and a <br />study addressing the potential for planned flow spikes to limit this species was initiated in 1998. Starting <br />in 1994, nonnative fishes were removed from the river when they were captured, and in 1998 a study to <br />utilize collected channel catfish by stocking them in ponds on the Navajo Reservation began. Nonnative <br />fish monitoring, and continued removal of nonnative fishes, are part of the Long Term Monitoring Plan. <br /> <br />September 2000 <br /> <br />4-4 <br /> <br />Program Evaluation Report <br />