7407

• UCREFRP Catalog Number: 7407
• Author: McAda, C. W.
• Title: Results of the Interagency Standardized Monitoring Program, 1988.
• USFW Year: 1989.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

HUMPBACK CHUB MONITORING
Methods
Humpback chub monitoring was conducted in September in Black Rocks and Westwater
Canon on the Colorado River (Figure 3). Sampling was done using trammel--nets
set about 1500 hr and checked regularly until dark. All captured fish were
identified and enumerated. All Gila were photographed against .a white background
with a 1-cm-grid pattern and given a numbered tag before release. In addition,
seven morphomeristic measurements and counts were taken from each fish before
release: total length, depth of nuchal depression, length of dorsal-fin base,
length of anal-fin base, weight, number of principal dorsal and anal-fin rays.
Black Rocks
135-136
Westwater ,
Canyon
114-122
Dolores River
o ~ 20
~ ~
Green River
Grand Junction
Figure 3.--River reaches sampled during humpback chub monitoring.
Results
A total of 103 humpback chub was collected in Westwater Canyon and 53 were
collected in Black Rocks (Table 8). Humpback chub was the most common fish
collected in each river reach, followed in abundance by roundtail chub and
channel catfish. Only four Gila were captured that could not be categorized as
humpback chub or roundtail chub. Relatively few individuals of other species
were collected (Table 8).
Morphometric measurements for the Gila collected during the sampling are provided
in Table 9.
9