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. . 7. 12/mile. This reach is characterized as having the most channel complexity. Based on this comparison it is reasonable to assume the lower Duchesne River plays a greater role in providing nursery habitat and also maintaining populations of native fishes. . Fish Data Larval.- Endangered fish collected during larval sampling efforts included one suspected razorback sucker measuring 13 mm TL collected in a light trap in a backwater at river-mile 1.6 on 27 May 1998. The location ofthis collection is within the area of the Duchesne River where flow velocity is influenced by the stage of the Green River. However, considering the magnitude of river flows (1110 - 1340 cfs) leading up to and including the day of collection, it is reasonable to believe that this larvae was produced in the Duchesne River. This specimen appears morphologically typical of razorback sucker, however the pigmentation and developmental state characteristics have been observed in rare instances among bluehead sucker larvae. . . . The lack of any other positively identified bluehead sucker larvae in the 1998 samples strongly suggests that the specimen was a razorback sucker. Unfortunately, the specimen is preserved in formalin and with current technology cannot be verified by DNA analysis (pers. conv. Darrel Snyder, Larval Fish Laboratory, Colorado State University 1998). Two juvenile Colorado pikeminnow (67 mm and 69 mm) were also collected during larval sampling efforts using a seine in a backwater at river-mile 3.6 on 1 July, 1999. Other larval native species collected (Tables 1- 3) were chubs (Gila ssp), flannelmouth suckers, bluehead suckers and speckled dace (Rhynichthys osculus). Juvenile native species collected included roundtail chub (Gila robusta), speckled dace and flannelmouth sucker. Larval or young-of-the-year (YOY) nonnative species captured include common carp (Cyprinus carpio), fathead minnows (Pimephales promelas), green sunfish (Lepomis cyanellus), red shiners (Notropis lutrensis), sand shiners (N. Stramineus), smallmouth bass (Micropterus dolomieui), and white suckers (c. commersoni). Juvenile and adult nonnative fish collected include brook stickleback (Culaea inconstans), black bullhead catfish (Ictalurus melas), channel catfish (1 punctatus), carp, fathead minnow, green sunfish, red . . . . 7 .