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WESTWATER CAN.: IBNER~ CAB.(RY 124.1) WESTWATER CI1DL: OOtJCiAR BAR (RM 121.5) 3S 5.5 ~ ~ _~ T _~ W h 2 2 Z = ~ ~ 15 ~ 1.6 N _ N 1 ~ 1 W ty vos T v~ o 1088 1989 1000 1901 1992 1993 1004 1095 1906 ° 1088 1089 1090 1001 1902 1055 1004 1996 1006 ~l~®RT AFB®RT WESTWATER G4N.: NADES BAR (RM 120.0) . ~.5 ,.., 3 D: O _ ~` m Z ~ ~ 1.5 S N = 1 41 a T ` U 0.5 ~ i - - 0 1068 1989 1090 1001 i902 1090 1004 1005 1006 ' X163®~ '. Figure 16. ~A longterm comparison of humpback and roundtail chub standardized trammel net catch rates (fish /23m net hour) with S.E. bars at three sampling sites in Westwater Canyon, Colorado Rivet, 1988 -1996. All daxa collected between late August and early October. In 1990, the shift fi-om humpbacks to roundtails was first detected at Mner's Cabin, ax the upper terminus of Westwater Canyon. A similar shift was detected two years later at the two lower sites. Seperal years of low flows preceded 1990 and continued until 1993. It was assumed the shift in Gila spp, abundance was related to that dry cycle. The high flows of 1993. and 1995, appear to have reestablished a balance of these two native speaes. Project catch rates were lower than those recorded when UDWR started monitoring the canyon chubs in i 988, however there were differences in sampling protocols. DRAFT 36