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<br />fish that were present in most samples include the bluehead sucker, mottled sculpin, and
<br />speckled dace, The tlatmelmouth sucker was also collected, but only on two sampling
<br />occasIOns.
<br />
<br />San Juan River, The San Juan River upstream from Navajo Reservoir was sampled on
<br />18 occasions during the early 1990s, Four native fish species (bluehead sucker,
<br />llannelmouth sucker, mottled sculpin and speckled dace) were common in collections,
<br />while one native species (roundtail chub) was only present (usually in low numbers)
<br />during halfofthe sampling events, Nine non-native species (black bullhead, channel
<br />catfish, white sucker, common carp, small mouth bass, fathead minnow, kokanee salmon.
<br />rainbow trout. and brown trout) were present in collections, The black bullhead, channel
<br />catfish, common carp, small mouth bass and kokanee salmon are all species that had not
<br />been collected in the San Juan River prior to sampling conducted during the] 990s. The
<br />white sucker, rainbow trout, and brown trout were common in occurrence and seem to
<br />have well established populations.
<br />
<br />General trends in fish collections from 1990 to 1994 indicate that fish communities have
<br />undergone some changes in species composition in several tributaries to the San Juan,
<br />Roundtail chubs have been collected from the Animas, Florida, La Plata, and Mancos
<br />rivers downstream of Navajo Reservoir, and the Navajo and San Juan rivers upstream
<br />from Navajo Reservoir. In most of these systems however, roundtail chubs appear to be
<br />restricted to a few specific locations (possibly confined by altitude, habitat and
<br />competition with non-native fish). Prior to 1964 roundtail chubs were found in most of
<br />the samples taken at the Animas River, and non-native fish were rare, Samples taken
<br />during the early 1990s indicated that five non-native fish had become established in the
<br />Animas River, and roundtail chubs were reported in less than 2% of the sampling events,
<br />
<br />The white sucker appears to have established populations in the Animas, Florida, Los
<br />Pinos, Navajo, Piedra, and San Juan River upstream from Navajo Reservoir. From fish
<br />collection data it appears that the white sucker had become established in tributaries
<br />upstream from Navajo Reservoir, but was rarely collected in other streams during the'
<br />1970s, Sampling during the 1990s indicated that the white sucker had become common
<br />in the Animas and Florida Rivers, but was still undetected in the Mancos River, La Plata
<br />River, and Mc Elmo Creek.
<br />
<br />Fish Sampling 1995-1999
<br />
<br />Fish sampling efforts have continued from 1995 through \999 on the Animas, and La
<br />Plata rivers as part of the data collection effort for the proposed Animas La Plata Project
<br />(S, Whiteman, Southern Ute Indian Tribe, personal communication), Much ofthe recent
<br />work has been included in the data provided in Appendix A, Most of the
<br />presence/absence data was similar to data from previous years. The only new fish
<br />species located in these studies that was not previously reported was the johnny darter
<br />(Etheostoma nigrum). This species was collected from the Animas River during 1997
<br />and 1998, Most of the recent fish collection data from the Animas River support the
<br />
<br />Draft Final Tributary Report
<br />Miller Ecological Consultants, Inc.
<br />
<br />January 31, 2000
<br />Page 19
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