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<br />00161)5
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<br />developed and initiated in 1991. An adult monitoring and radiotelemetry study was initiated and
<br />continued for the duration of the 7 -year research period. This study was conducted by the USFWS
<br />(Grand Junction), with assistance from NMGF, UDWR, and other agencies. This study addressed
<br />portions of Objectives 1,3, and 4 for adult and juvenile fish. Generally, the study consisted of
<br />three electrofishing trips on portions of the study area that, when combined, created an annual
<br />sampling of the entire study area, from Farmington, New Mexico, to Mexican Hat, Utah. This
<br />study provided information on relative abundance, distribution, and age classes of all fish species
<br />collected. During 1991 and 1992, the portion of river within the fluctuation zone of Lake Powell
<br />and below a waterfall that developed in the late 1980s was sampled by the Bureau as a subset of
<br />this study. The area below Mexican Hat, Utah, was included in the USFWS study in 1993 and
<br />thereafter. In addition, captured adult Colorado pikeminnow were radio-tagged and monitored to
<br />determine habitat use and movement. The UDWR was responsible for an early life stage, nursery
<br />habitat, and larval drift study initiated in 1991 that continued throughout the research period. This
<br />study, which used seining as the primary sampling method, addressed Objectives 1,3, and 4 for
<br />young of large-bodied species and young and adults of small-bodied species. The study was
<br />generally designed to locate young Colorado pikeminnow, although all species were sampled by
<br />seining backwaters and other low-velocity habitats. The study area was from Hogback Diversion
<br />to Clay Hills Crossing, Utah. In addition to seining, drift nets were used for larval drift sampling
<br />at two sites, Mexican Hat, Utah, and Four Corners. The larval drift sampling was assumed by the
<br />University of New Mexico in 1995. In 1993, 1994, and 1995 the Bureau conducted additional
<br />nursery habitat surveys in late summer and fall, looking primarily for young Colorado pikeminnow
<br />in the river near the Lake Powell interface below the area that the UDWR sampled. This study was
<br />discontinued in 1995, when Lake Powell inundated the lower study area; sampling that year (1995)
<br />was ineffective because oflake elevation.
<br />
<br />In 1991, the NMGF began investigating the fish fauna of secondary channels. This study continued
<br />through the entire 7-year research period and consisted of electrofishing surveys in the spring and
<br />seining surveys in the late summer and autumn. This study addressed Objectives I and 3 and was
<br />initiated because other studies did not sample intensively in secondary channels, which made up
<br />a fairly large amount of potential habitat in the river. The study area was from Hogback Diversion
<br />to Bluff, Utah, where the majority of secondary channels existed in the river.
<br />
<br />The other core study initiated in 1991, a nonnative fish interaction study, was conducted by the
<br />USFWS (Albuquerque) for the entire 7-yearresearch period. This study addressed Objective 6 of
<br />the 7-year research plan and used information from the adult monitoring, early life history, and
<br />secondary channel studies to determine distribution and abundance of nonnative fish, primarily
<br />channel catfish, common carp, and other large-bodied predators. Specimens of nonnative fish were
<br />taken for food habits analysis, and invertebrate samples were taken to examine food availability.
<br />In 1996, radiotelemetry of channel catfish was added to determine their habitat use and movement.
<br />The study area consisted of the San Juan River from Farmington, New Mexico, to Clay Hills
<br />Crossing, Utah.
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<br />2-8
<br />
<br />Program Evaluation Report
<br />
<br />September 2000
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