9725

• UCREFRP Catalog Number: 9725
• Author: Paukert, C.P., L.G. Coggins and C.E. Flaccus.
• Title: Distribution and movement of humpback chub in the Colorado River, Grand Canyon, based on recaptures.
• USFW Year: 2006.
• USFW - Doc Type: Transactions of the American Fisheries Society
• Copyright Material: YES

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540
PAUKERT ET AL.
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FIGURE I. Location of the Little Colorado River in relation
to the Colorado River and Grand Canyon, Arizona. Sampling
for humpback chub primarily occurs between the Paria River
(rkm 27) and Diamond Creek (rkm 389).
pikeminnow Ptychocheilus lucius make substantial
migrations during spawning (Tyus 1991; Irving and
Modde 2000), whereas razorback sucker Xyrauchen
texanus also migrate substantial distances but may use
different spawning locations m different years (Modde
and Irving 1998), emphasizing the need to evaluate
distribution and movement over multiple years. Un-
derstanding the distribution and movement of hump-
back chub in Grand Canyon is needed before
conservation and management strategies to recover
this species can be fully evaluated.
The objective of this study was to summarize
recaptures of passive integrated transponder (PIT)-
tagged fish to determine the distribution and movement
of humpback chub throughout Grand Canyon in all
seasons. We wanted to determine if movement patterns
and distribution differed by fish size or temporal scale,
and if their distribution and movement was similar to
that of other large-river fishes. Our study focused on
the large-scale movement throughout Grand Canyon
over a 12-year period as other studies have focused on
the movement of fish within the LCR and within-year
movements, including the spawning season (e.g.,
Kaeding and Zimmerman 1983; Douglas and Marsh
1996; Gorman and Stone 1999; Valdez and Hoffnagle
1999).
Methods
We used a long-term monitoring data set to
determine the distribution and large-scale movement
of humpback chub throughout 389 km of the Colorado
River in Grand Canyon from the Paria River to
Diamond Creek (Figure 1). Patterns in distribution
and movement were evaluated to determine the extent
of movement of humpback chub between the main-
stem Colorado River and the tributaries (e.g., LCR). To
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FTGURE 2.-Proportion of sampling effort by month (1 =
January, etc.) for trammel nets (net sets), hoop nets (net sets),
and eiectrofishing (stations) used to collect humpback chub in
the main-stem Colorado River and Little Colorado River, May
1989 to October 2002.
minimize bias and pseudoreplication associated with
fish recaptured immediately after capture, we used only
recaptures that were at large at least 14 d between
capture and recapture, which would minimize the
effects of fish recaptured during the same multiday
sampling events (typically 8-14 d) and would provide
time for fish to allow movement among river reaches.
The fish were separated into three categories by total
length (average of length recorded at capture and
recapture): less than 200 nun, 200-299 nun, and 300
nun or larger. The minimum size of adult humpback
chub is about 200 nun (Meretsky et al. 2000; USFWS
2002).
Humpback chub were collected from 1989 to 2002
by a variety of gears in the main-stem Colorado River
(e.g., trammel nets, hoop nets, and boat electrofishing),
but primarily by hoop nets in the tributaries (Figure 2;
Valdez and Ryel 1995; Gorman and Stone 1999;
Coggins et al. 2006). Sampling effort was variable
across seasons in the main-stem Colorado River and
more focused during early spring in the Little Colorado
River (Figure 2). Although variable, effort was