8177

• UCREFRP Catalog Number: 8177
• Author: Valdez, R. A., B. R. Cowdell and L. Lentsch.
• Title: Overwinter Survival of Age-0 Colorado Pikeminnow in the Green River, Utah, 1987-1995\
• USFW Year: 1999.
• Copyright Material: NO

Table 4. Number of age-O Colorado pikeminnow, geometric mean CPUE, and mean total
length for the 1989-93 year classes in the upper Green River (Reach 4, RK 346-515).
Asterisks denote significant differences (Students 't', P<O.05) in mean CPUEs
between fall and spring of a given year class.
Year Class No. Seine Hauls No.Age-O CPUE (#/100 m2) Survival Mean TL (mm)
Sample (Hauls with Age-O) (standard (percent) (range)
Periods deviation)
1989
Fall '89 84 (19) 61 0.48 (2.18) 41 (28-59)
Spring '90 76 (20) 25 0.46 (1.97) 96 44 (34-61 )
1990
Fall 1990 84 (42) 281 1.77 (3.29) 42 (28-60)
Spring 1991 80 (22) 47 0.51 (2.08)* 29 50 (35-68)
1991
Fall 1991 80 (51) 526 3.76(4.31) 38 (21-58)
Spring 1992 82 (29) 184 1.18 (3.53)* 31 43 (27-60)
1992
Fall 1992 80 (36) 175 1.25 (2.89) 42 (26-60)
Spring 1993 78 (16) 87 0.48 (2.53)* 38 44 (29-68)
1993
Fall 1993 80 (26) 305 1.39 (4.01) 36 (2) -59)
Spring 1994 76 (24) 90 0.86 (2.83)* 62 40 (29-58)
1994
Fall 1994 84 ( 4) 15 unable to compute (60-80)
Spring 1995 76 ( 3) 3 CPUEs ( -61)

Sympatric Fishes

Ten species of fish were found in backwaters sampled, including five native species and five
non-native species. The native species included Colorado pikeminnow, tlannelmouth sucker
(( 'aloSlomus latipinnis), bluehead sucker (c. discobolus), speckled dace (Rhinichthys osculus), and
Gila sp. (probably roundtail chub, Gila robusta). The non-native species included red shiner
(( )prinella lutrensis), sand shiner (Notropis stramineus), fathead minnow (Pimephales promelas),
channel catfish (Ictalurus punctatus), and common carp (Cyprinus carpio). The most abundant
species in "primary backwaters" in Reach 3 during 1987-95 were red shiners, sand shiners, and
fathead minnows (Figure 7). Red shiners far outnumbered all other species in both fall and spring
samples, except for spring 1995, when sand shiner catch rates were highest. Age-O Colorado
pikeminnow were typically the second to fourth most abundant species in primary backwaters. The
numbers and catch rates of the four native species, besides Colorado pikeminnow, were too small
to illustrate in Figure 7 and are presented in Table 6.

]4