9548

• UCREFRP Catalog Number: 9548
• Author: Finney, S.
• Title: Adult and Juvenile Humpback Chub Monitoring for the Yampa River Population, 2003-2004.
• USFW Year: 2006.
• USFW - Doc Type: 133,
• Copyright Material: NO

forty-nine Gila spp. were collected, of which 30 were questionably identified as G. cypha
(Snyder et al. 2006). Gila spp. comprised 2.6% of the juvenile fish collected (Table 4).
Mean length of the questionably identified juvenile Gila cypha was 47.9 mm TL
and Gila robusta was 43.9 mm TL (Figure 3). The length frequency data show two year
classes, having only one fish in the age-1 class. These length distributions are similar to
the two year classes (age-0 <70mm TL and age-1, 70-130 mm TL) identified for Gila
spp. in the Yampa River (Steve Ross, University of Southern Mississippi, personal
communication) and those identified from Westwater Canyon (Chart and Lentsch 1999).
Juvenile G. robusta were found in two samples from Island Park and G. robusta
and G. cypha were found in mid and lower Yampa Canyon (rkm 18.5-37; Figure 4).
Juvenile humpback chub are distributed further downstream than the adult population.
Juvenile Gila spp. have been previously found in Island Park and in the alluvial reaches
of the Middle Green River (USFWS, Vernal, Utah, unpublished data).
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