9350

• UCREFRP Catalog Number: 9350
• Author: Hawkins, J., T. Modde and J. Bundy.
• Title: Ichthyogauna of the Little Snake River, Colorado, 1995 with Notes on Movements of Humpback Chub.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

I
I
I
I
I
I
I
,I
I
I
I
I
I
I'
I
I
I
I
I

equal among sites Ix = 553 m2, Table 2), most larvae (n = 5809) were collected
from the lower reach while only 33 larvae were collected from the middle and upper
reaches combined. All Gila spp. less than 55-mm total length, including larvae,
were preserved and identified in the laboratory (n = 234) except for eight juveniles
that were identified and released in the field. All juveniles returned to the
laboratory were subsequently identified as roundtail chub and all larvae (n = 14)
were identified only to genus because there were no suitable diagnostic
morphometric or meristic characteristics to separate small, larval, humpback chub
from roundtail chub. Thirteen of the Gila larvae were between 12 and 16-mm total
length and one was 24-mm total length.

Sixteen species were captured in the juvenile or adult life stage, including
eight large-bodied species and eight small-bodied species. Three native species,
flannelmouth sucker, bluehead sucker, and roundtail chub composed 93% of all
large-bodied species collected. Relative abundance of these three species was
relatively constant in all reaches and seasons (Tables 8 and 9), except that from
spring to autumn, flannel mouth sucker abundance decreased and bluehead sucker
abundance increased lTable 8). Nonnative channel catfish, white sucker, and
common carp were few and together represented only 7% of the large-bodied taxa.
Native Colorado pikeminnow, humpback chub, and flannelmouth sucker hybrids
were extremely rare and composed less than 1 % of the remaining large-bodied taxa
(Tables 8 and 9). Native fishes generally included all life stages and were
represented by a wide range of lengths (Table 5 and Figure 6). Nonnative fishes
generally included only some life stages and were limited to disjunct, mostly larger
length-groups (Table 5 and Figure 7).

During baseflow, 248 large-bodied fish were estimated to reside in the
upper-site, low-flow pool, representing three native and two nonnative species

13