WSP12249

• File Number: 8240.200.10.B
• Description: UCRBRIP - Riverine Fish Flow Investigations
• Basin: Colorado Mainstem
• Date: 6/1/2004
• Author: CDOW
• Title: Riverine Fish Flow Investigations 2004
• Water Supply Pro - Doc Type: Publication

data also suggested that hybridization between white sucker and native sucker may have
increased in the ten-year period between samples (Table 22),

Table 21, Species composition at the Gunnison River sites in 1992 and 1993 (Burdick 1995),

Gunnison River Reach 6 (Austin) Reach 5 (Delta) Reach 4 (Escalante)
Species 1992.1993 1992. t993 1992 -1993
Flannelmouth sucker 19,3 - 23,1% 21,6 - 22,8% 34,8 - 33,3%
Bluehead sucker 34,8 - 27.2% 44.4 - 47,5% 32.3 - 37,5%
Roundta,l chub 0,1 - 0,5% 6,1 - 6,1% 19,5 - 13,0%
White S, + hybrids 24.0 - 25,3% 11.4 - 7,9% 4.0 - 4.6%
Carp 8.4 - 9,0% 13,5 - 11,6% 6,9 - 9.8%
Brown trout 4.7 - 5,8% 1.4 - 1,1% 1.4 - 1,2%
Rainbow trout 8,7 - 9,0% 1,6 - 1,5% 0,8 - 0,2%
Sam pie size 1565 . 1344 3632 - 2914 1347 . 1335

Table 22, Percent of native sucker in total sucker catch and percent of hybrids with cin total
white sucker & hybrids catch at the Gunnison River (Burdick 1995),

Gunnison River Reach 6 I Reach 5 I Reach 4 Reach 6 I Reach 5 I Reach 4
% native sucker (all species) % hybrids (total WS & hybrids)
1992 69% 84% 94% 26% 13% 31%
1993 67% 88% 93% 44% 30% 43%
2003 69% 74% 88% 56% 32% 32%
Total suckers caotured (n \ WS & hvbrids caotured (n)
1992 1221 2841 973 151 83 32
1993 1016 2321 1018 99 57 17
2003 1705 1379 1171 299 116 46

Channel catfish, northern pike, and smallmouth bass were not captured in the
Gunnison River, Austin had the largest mean size for all species (Table 21). Brown trout
may prey on small fish at Austin since tlannelmouth sucker less than 40 cm and bluehead
sucker less than 30 were uncommon (Figure A2- 4 & A2-1). The lack of small native sucker
would also result if spawning sites are located downstream of this site,

Flannelmouth sucker and bluehead sucker less than 40 cm and 30 cm respectively
were common at both Delta (Figures A2-2 & A2-7) and Escalante (Figures A2-8 & A2-3).
Also Age-O and Age-I round tail chub and carp were both common at Delta (Figures A2-1 0
& A2-25) and Escalante (Figures A2-II & A2-26), but not at Austin (Figures A2-9 and A2-
24), Escalante had the smallest mean lengths of the Gunnison River sites suggesting this area
has increase nursery habitat availability (Table 23).

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