9478 - Laserfiche WebLink

Home Browse Search

. . channel. Further down river, near river-mile 10 (Bow tie), large cobble bar complexes were scoured and realigned. Flows remained near or above 300 cfs throughout July and August before increasing to near 1000 cfs for much of September. Nursery Habitat . . Native fishes provided the traditional prey base for adult Colorado Pikeminnow in the middle Green River, and production from the Duchesne River and other tributaries has been identified as playing and important role in producing this prey base (Tyus and Saunders 2001). Nursery habitat in the lower Duchesne River is likely important for maintaining healthy resident populations of native and endangered fish species. This may be especially important for more sedentary species such as the roundtail chub, and speckled dace. The lower portion of the White River historically supported a higher proportion of nonnative fish, with the percentage increasing near the confluence with the Green River (Miller et. al. 1982; Lanigan and Berry 1981). Red shiner have been reported as dominating the fish community in the lower White River (Lanigan and Berry 1981; Miller et al. 1982). The fish community composition of the lower White River was reported by Lanigan and Berry (1981) as 80.4% nonnatives and 19.6% natives. This is comparable to the composition observed in this study. A comparison of available nursery habitat was made between the lower Duchesne River and the lower White River to provide additional insight into the relative role the Duchesne River may play in maintaining the native and endangered fish community. Surveys conducted by UDWR in October 2000 on the lower White River indicate the frequency of nursery habitat encountered on the lower 24 miles of the White River is less than that encountered during this study on the lower 34 miles of the Duchesne River. Nursery habitats on the lower 14.7 miles of the White River were sampled on 3 October and the reach of river from river-mile 24.4 - 14.7 was sampled on 20 October, 2000. This effort was directed at monitoring young-of-the-year (YOY) Colorado pikeminnow, other native and nonnative fishes using nursery habitats of the lower White River. All low flow habitats encountered were recorded for both rivers. On the White River, the number oflow-flow habitats encountered on the lower 14.7 miles was nine or .611mile. For the reach of the White River from river-mile 24.4 - 14.7, fifteen or 1.5/mile were encountered. Comparatively, on the three study reaches of the lower Duchesne River, the average number of nursery habitats encountered was approximately 5.7/mile. On average, the Uinta reach contained the most nursery habitat at . . . . . . 6 .