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