WSP07867 - Laserfiche WebLink

Home Browse Search

o C) i'~ 1". ., C) IV No/emigonus cryso/eucas (golden shiner): The golden shiner was only encountered on two occasions during the historical sampling of these San Juan River tributaries. Both collections of this non-native species occurred in tributaries upstream of Navajo reservoir, Three individuals were collected from the Navajo River during 1972, amI two individuals were reported from the Los Pinos River during 1992, The golden shiner was not encountered during the habitat use study, Pimepha/es promelas (fathead minnow): Earliest reports of this non-native species in the study area of the San Juan drainage came from the Animas River during 1954, By the late] 970s this species had been reported from the Navajo River, and appeared to be well established in the La Plata River, Mancos River, Navajo Wash and Mc Elmo Creek, By 1992 the fathead minnow had been reported from all major tributaries of the San Juan River. After becoming established, the fathead minnow became a dominant fish species in at many locations, Streams with large populations of fathead minnows include the La Plata River, the lower Mancos River and Mc Elmo Creek. Due to the small adult size of this species it is often overlooked by the sampling techniques used in large rivers. It is likely that sizable populations of fathead minnows also exist in some systems that are difficult to sample, Fathead minnows were represented in the MEC habitat use data by adult and juvenile size classes. Representatives of both size classes were found inhabiting all three major habitat types. Juveniles were found primarily in glide habitat, while adult fathead minnows were collected mostly from pool habitat. Caloslomus commersoni (white sucker): Historical fish sampling in the San Juan drainage suggests that this non-native species has become established in several major tributaries, The first report of this species in the study area came from the Animas River during] 961. It was also reported with some frequency in early collections from tributaries upstream of Navajo Reservoir. Olson (1962b) indicated that this species had become established in the area now inundated by Navajo Reservoir, It is likely that the white sucker had become established in certain areas upstream of Navajo Reservoir prior to collections made during the early 1970s, The earliest reports of this species occurring in the Florida River came from collections made during 1983. By the early] 990s sampling efforts indicated that this species had become more common in the Florida River than in the Animas River, Sampling efforts at other locations during the 1990s indicated that the white sucker had become established (even dominant at some locations) in tributaries upstream of Navajo reservoir, however this species had still not been reported from most of the lower tributaries, As of] 998 the white sucker had not been reported from the La Plata River, Mancos River or McElmo Creek. (, During the habitat use study the white sucker was represented in collections by all three size classes, however most were juveniles, Only one individual in the "young ofthe year" (YOY) size class was collected during this study, This fish was captured while occupying riffle habitat, Juvenile white suckers were captured from each habitat type, The data suggests that most juvenile white suckers reside in glide habitat, Adults were found in glide habitat and pool habitat. No white sucker adults were encountered in riffle habitat. Draft Final Tributary Report M iller Ecological ConsuUants, J nc. January 31,2000 Page 24