scholarly journals Grand Canyon Humpback Chub Population Improving

Fact Sheet ◽  
2007 ◽  
Author(s):  
Matthew E. Andersen
Keyword(s):  
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.

Experimental infection of the endangered bonytail chub (Gila elegans) with the Asian fish tapeworm (Bothriocephalus acheilognathi): impacts on survival, growth, and condition

2006 ◽  
Vol 84 (10) ◽  
pp. 1383-1394 ◽  
Author(s):  
S.P. Hansen ◽  
A. Choudhury ◽  
D.M. Heisey ◽  
J.A. Ahumada ◽  
T.L. Hoffnagle ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Grand Canyon ◽  
River System ◽  
Health Condition ◽  
Infected Fish ◽  
Control Fish ◽  
Potential Threat ◽  
Humpback Chub ◽  
Bothriocephalus Acheilognathi ◽  
Negative Impacts

Bothriocephalus acheilognathi Yamaguti, 1934, a tapeworm known to be pathogenic to some fish species, has become established in the endangered humpback chub ( Gila cypha Miller, 1964) in Grand Canyon, USA, following the tapeworm’s introduction into the Colorado River system. The potential impact of this tapeworm on humpback chub was studied by exposing the closely related bonytail chub ( Gila elegans Baird and Girard, 1853) to the parasite under a range of conditions that included potential stressors of humpback chub in their natal waters, such as abrupt temperature change and a limited food base. Survival of infected fish under low food rations was considerably lower than that of control fish, and mortality of infected fish began 20 days earlier. Growth of infected fish was significantly reduced, and negative changes in health condition indices were found. No significant negative impacts were revealed from the synergistic effects between temperature shock and infection. Bothriocephalus acheilognathi does present a potential threat to humpback chub in Grand Canyon and should be considered, along with conventional concerns involving altered flow regimes and predation, when management decisions are made concerning conservation of this endangered species.

Parasitism and Body Condition in Humpback Chub from the Colorado and Little Colorado Rivers, Grand Canyon, Arizona

2006 ◽  
Vol 18 (3) ◽  
pp. 184-193 ◽  
Author(s):  
Timothy L. Hoffnagle ◽  
Anindo Choudhury ◽  
Rebecca A. Cole
Keyword(s):  
Body Condition ◽  
Grand Canyon ◽  
Humpback Chub

scholarly journals Of Travertine and Time: Otolith Chemistry and Microstructure Detect Provenance and Demography of Endangered Humpback Chub in Grand Canyon, USA

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e84235 ◽  
Author(s):  
Karin E. Limburg ◽  
Todd A. Hayden ◽  
William E. Pine ◽  
Michael D. Yard ◽  
Reinhard Kozdon ◽  
...  
Keyword(s):  
Grand Canyon ◽  
Otolith Chemistry ◽  
Humpback Chub

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.

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