9716

• UCREFRP Catalog Number: 9716
• Author: Stone, D., and P. Sponholtz.
• Title: Translocation of young-of-year humpback chub above Chute Falls in the Little Colorado River, AZ, 2003 Interim Report.
• USFW Year: 2003.
• USFW - Doc Type: U.S. Fish and Wildlife Service
• Copyright Material: NO

levels in the tank were within 10 mg/L of the release site. The fish were then placed within
live cars secured in the LCR, monitored, and allowed to acclimate overnight until their
release the following morning. Throughout this trip the water at the LCR capture and
release sites and in the holding tank were periodically tested for dissolved oxygen,
conductivity, temperature, and pH using a Surveyor 3 Hydrolab (Hydrolab Corp., Austin,
Texas); CO2 levels were measured using the previously described titration technique.
Fall Monitoring trip
We conducted a fall monitoring trip from October 31-November 4, 2003 to survey the area
above Chute Falls for the presence of any previously translocated humpback chub. We
deployed twenty-two baited hoopnets from 14.2 to 16.74 RKM for three --24 hour hauls.
We also deployed two gill nets and one trammel net. We measured (TL) speckled dace,
Rhinichthys osculus, captured in the first eleven nets of the first haul, and then tallied
thereafter. We measured all other fishes for total length (TL) . Each humpback chub was
examined for an elastomer tag, held overnight in an aerated tank (so ingested bait could be
digested), inserted with a passive integrated transponder tag (Biomark, Inc.), and released.
We examined the digestive tracts of all large-bodied predatory fish for fish remains. In
addition, we instructed all personnel from prior downstream LCR and Colorado River
monitoring trips (i.e., July-November 2003) to examine humpback chub for yellow
elastomer tags to detect any translocated fish that may have migrated downriver.
Statistical Analyses and Comparisons
We compared numbers and proportions of fishes captured in hoopnets between the
reconnaissance and monitoring trips. Independent sample T-tests were used to examine
for significant intraspecific length differences of various species. Precursory Levene's Test
for Equality of Variances validated the use of pooled- vs. separate-variances T-tests. We
used pooled-variances T-tests to examine for significant humpback chub and fathead
minnow, Pimephales promelas, length differences between the two trips, and between
those humpback chub with and without visible elastomer tags captured during the
monitoring trip. Separate-variances T-tests were used to examine the length differences of
both speckled dace and common carp, Cyprinus carpio, between trips. The sample sizes
of speckled dace were sufficient to graphically compare the mean catch per unit effort
(CPUE) ± 2 standard error between trips; nonoverlapping error bars were considered
significantly different. We constructed length frequency histograms of humpback chub from
the July 2003 translocation and November 2003 monitoring trips. To examine for
concurrence over time, we compiled and overlaid by location the mean CO2 levels from the
July 2003 reconnaissance trip, along with those collected in July 1993 by Mattes (1993)
and in June 1994 by Robinson et al. (1996). Because "RKM" accuracy has improved with
newer technology, we updated the historical locations to concur with those from this study.
The names and descriptions of known sites given by Mattes (1993) and location map
detailed in Robinson et al. (1996) made this possible. Discharge data from U.S. Geological
Survey gage 09402300, located above the mouth of the LCR, allowed for an inspection of
flow conditions in the Colorado River since humpback chub were first translocated above
Chute Falls.
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