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

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GUNNISON RIVER

The fish populations in the Gunnison River at Austin, Delta and Escalante were
distinctive, Flannelmouth sucker and bluehead sucker were common to abundant at all three
locations in 2003, Native fish comprised 62.7% of the catch at Austin, 70,1 % at Delta and
83.1 % at Escalante for captured fish over 15 em (Table 20). Flannelmouth sucker had the
greatest variability between sites and was 17% at Austin, 41 % at Delta and 29% at Escalante,
Bluehead sucker composition was also variable between sites and was 44% at Austin, 23% at
Delta and 42% at Escalante, Roundtail chub composition increased in the downstream
direction with one percent at Austin, six percent at Delta and 13% at Escalante (Table 20).

Brown trout were common at Austin but not downstream, while carp were
uncommon at Austin but common downstream. White sucker were common Austin and
Delta. Water temperature difference likely explained the higher abundance of brown trout at
Austin and may be a factor for white sucker,

Table 20. Species composition at the Gunnison River sites in 2003,

Gunnison River Austin Delta Escalante
Species 2003 2003 2003
Flannelmouth sucker 17.6% 41.2% 28,7%
Bluehead sucker 44.4% 22,7% 41,8%
Roundtail ,:hub 0,7% 6,2 12,5%
White S. + hybrids 28% 22,7% 9,6%
Carp 1,8% 6,5% 6,2%
Brown trout 6,7% 0,6% 1,1%
Ra i n bow trou t 0,8% 0,1% 0%
Sample size 1934 1622 1475
Austin Delta Escalante
White sucker 43.4% 67,9% 67,6%
White X flannelmouth 31,9% 23,6% 18,3%
While x bluehead sucker 24,7% 8.4% 14,1%

A difference was noted in the composition of white sucker and its apparent hybrids
between sites, White sucker, bluehead sucker and white sucker x bluehead sucker hybrids
were highest at the Austin site (Table 20), White sucker x tlannelmouth sucker hybrids were
also highest at Austin even though pure tlannelmouth sucker were less common at Austin.

Species composition for native sucker and roundtail chub observed in 2003 (Table
20) were fairly similar to that reported for collections in 1992 and 1993 (Burdick 1995)
(Table 21), However white sucker composition appeared to have increased in the Gunnison
River during the past ten years (Table 21),

The native sucker percentage of total suckers (tlannelmouth, bluehead, white and
hybrid suckers) was similar at Austin (Reach 6) in 2003 with the 1992 and 1993 data (Table
22), but was somewhat less at Delta (Reach 5) and Escalante (Reach 4) (Table 22), These

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