Modelling effects of discharge on habitat quality and dispersal of juvenile humpback chub(Gila cypha) in the Colorado River, Grand Canyon

2004 ◽  
Vol 20 (4) ◽  
pp. 379-400 ◽  
Author(s):  
Josh Korman ◽  
Stephen M. Wiele ◽  
Margaret Torizzo
Keyword(s):  
Habitat Quality ◽  
Colorado River ◽  
Grand Canyon ◽  
Humpback Chub

Distribution and Movement of Humpback Chub in the Colorado River, Grand Canyon, Based on Recaptures

2006 ◽  
Vol 135 (2) ◽  
pp. 539-544 ◽  
Author(s):  
Craig P. Paukert ◽  
Lewis G. Coggins ◽  
Christopher E. Flaccus
Keyword(s):  
Colorado River ◽  
Grand Canyon ◽  
Humpback Chub

scholarly journals Body Condition of Endangered Humpback Chub in Relation to Temperature and Discharge in the Lower Colorado River

2017 ◽  
Vol 8 (1) ◽  
pp. 333-342 ◽  
Author(s):  
Forest P. Hayes ◽  
Michael J. Dodrill ◽  
Brandon S. Gerig ◽  
Colton Finch ◽  
William E. Pine III
Keyword(s):  
Colorado River ◽  
Grand Canyon ◽  
Management Program ◽  
Parameter Estimates ◽  
Water Release ◽  
Fish Removal ◽  
Glen Canyon Dam ◽  
Management Actions ◽  
Humpback Chub ◽  
Glen Canyon

Abstract Determining the population status of endangered Humpback Chub Gila cypha is a major component of the adaptive management program designed to inform operation of Glen Canyon Dam upstream from Grand Canyon, Arizona. In recent decades, resource managers have identified a portfolio of management actions (with intermittent implementation) to promote population recovery of Humpback Chub, including nonnative fish removal, changes in water release volumes and discharge ramping schedules, and reductions in hydropower peaking operations. The Humpback Chub population in Grand Canyon has increased over this same period, causal factors for which are unclear. We took advantage of unusual hydrology in the Colorado River basin in 2011 to assess trends in juvenile Humpback Chub length–weight relationships and condition in the Colorado River below Glen Canyon Dam as well as in the unregulated Little Colorado River. Within each river, we observed higher length–weight b-parameter estimates (exponent of the standard power equation) at higher water temperatures. We also found higher slope estimates for the length–weight relationship at higher temperatures in the Little Colorado River. Slope estimates were more variable in the Colorado River, where mean water temperatures were more uniform. The next step is to examine whether Humpback Chub length–weight relationships influence population metrics such as abundance or survival. If these relationships exist, then monitoring condition in juvenile Humpback Chub would provide a quick and low-cost technique for assessing population response to planned management experiments or changing environmental conditions.

scholarly journals Effects of Turbidity on Predation Vulnerability of Juvenile Humpback Chub to Rainbow Trout and Brown Trout

2016 ◽  
Vol 7 (1) ◽  
pp. 205-212 ◽  
Author(s):  
David L. Ward ◽  
Rylan Morton-Starner ◽  
Ben Vaage
Keyword(s):  
Rainbow Trout ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Colorado River ◽  
Grand Canyon ◽  
Management Tool ◽  
Native Fish ◽  
Management Options ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Humpback Chub

Abstract Predation on juvenile native fish by introduced rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta is considered a significant threat to the persistence of endangered humpback chub Gila cypha in the Colorado River in Grand Canyon. Diet studies of rainbow trout and brown trout in Glen and Grand canyons indicate that these species eat native fish, but impacts are difficult to assess because predation vulnerability is highly variable depending on the physical conditions under which the predation interactions take place. We conducted laboratory experiments to evaluate how short-term predation vulnerability of juvenile humpback chub changes in response to changes in turbidity. In overnight laboratory trials, we exposed hatchery-reared juvenile humpback chub and bonytail Gila elegans (a surrogate for humpback chub) to adult rainbow trout and brown trout at turbidities ranging from 0 to 1,000 formazin nephlometric units. We found that turbidity as low as 25 formazin nephlometric units significantly reduced predation vulnerability of bonytail to rainbow trout and led to a 36% mean increase in survival (24–60%, 95% CI) compared to trials conducted in clear water. Predation vulnerability of bonytail to brown trout at 25 formazin nephlometric units also decreased with increasing turbidity and resulted in a 25% increase in survival on average (17–32%, 95% CI). Understanding the effects of predation by trout on endangered humpback chub is important when evaluating management options aimed at preservation of native fishes in Grand Canyon National Park. This research suggests that relatively small changes in turbidity may be sufficient to alter predation dynamics of trout on humpback chub in the mainstem Colorado River and that turbidity manipulation may warrant further investigation as a fisheries management tool.

Long-Term Monitoring of an Endangered Desert Fish and Factors Influencing Population Dynamics

2013 ◽  
Vol 4 (1) ◽  
pp. 163-177 ◽  
Author(s):  
David R. Van Haverbeke ◽  
Dennis M. Stone ◽  
Lewis G Coggins ◽  
M. J. Pillow
Keyword(s):  
Colorado River ◽  
Adult Life ◽  
Grand Canyon ◽  
Management Program ◽  
Glen Canyon Dam ◽  
Abundance Estimates ◽  
Humpback Chub ◽  
Native Fishes ◽  
Glen Canyon ◽  
Flannelmouth Sucker

AbstractThe lower perennial corridor of the Little Colorado River in Grand Canyon, Arizona, is numerically dominated by endemic desert fishes and therefore significant for conservation of these species. From 2000 to 2012, the U.S. Fish and Wildlife Service conducted monitoring of native fishes in the Little Colorado River near its confluence with the Colorado River. The primary focus of these efforts was to estimate the spring and fall abundance of native fishes, especially the federally endangered humpback chub Gila cypha. Because humpback chub in Grand Canyon are influenced by operations of Glen Canyon Dam, our efforts provide managers of the Glen Canyon Dam Adaptive Management Program with abundance estimates and trends of humpback chub in the Little Colorado River, the most important tributary in Grand Canyon for spawning and production of this species. From 2001 to 2006, the spring abundance estimates of humpback chub ≥150 and ≥200 mm remained relatively low (≤3,419 and ≤2,002 fish, respectively), thereafter significantly increasing to highs of 8,083 and 6,250, respectively, by spring 2010. Also from 2000 to 2006, the fall abundance estimates of humpback chub were substantially below those abundances estimated after 2006. In addition, flannelmouth sucker Catostomus latipinnis and bluehead sucker Catostomus discobolus showed post-2006 increases in relative abundance, suggesting a systemwide event occurred that was beneficial to native fishes. Most of the increases of humpback chub occurred during the spring season in the reaches of the Little Colorado River between 5 and 13.57 km upstream from the confluence. Successful production of age 0 year classes of humpback chub may be partially driven by hydrograph dynamics of the Little Colorado River, whereas water temperatures and predation pressures in the mainstem Colorado River likely influence survivorship of native fishes into subadult and adult life stages.

scholarly journals Factors controlling the abundance of rainbow trout in the Colorado River in Grand Canyon in a reach utilized by endangered humpback chub

2016 ◽  
Vol 73 (1) ◽  
pp. 105-124 ◽  
Author(s):  
Josh Korman ◽  
Michael D. Yard ◽  
Charles B. Yackulic
Keyword(s):  
Rainbow Trout ◽  
Colorado River ◽  
Feasible Solution ◽  
Grand Canyon ◽  
Small Population ◽  
Negative Effects ◽  
Glen Canyon Dam ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Threefold Increase ◽  
Humpback Chub

We estimated the abundance, survival, movement, and recruitment of non-native rainbow trout (Oncorhynchus mykiss) in the Colorado River in Grand Canyon to determine what controls their abundance near the Little Colorado River (LCR) confluence where endangered humpback chub (Gila cypha) rear. Over a 3-year period, we tagged more than 70 000 trout and recovered over 8200 tagged fish. Trout density was highest (10 000–25 000 fish·km–1) in the reach closest to Glen Canyon Dam, where the majority of trout recruitment occurs, and was 30- to 50-fold lower (200–800 fish·km–1) in reaches near the LCR confluence ∼100 km downstream. The extent of rainbow trout movement was limited with less than 1% of recaptures making movements greater than 20 km. However, because of high trout densities in upstream source areas, this small dispersal rate was sufficient to explain the threefold increase in the relatively small population near the LCR. Reducing dispersal rates of trout from upstream sources is the most feasible solution to maintain low densities near the LCR to minimize negative effects of competition and predation on humpback chub.

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