Ontogenesis of Endangered Humpback Chub (Gila cypha) in the Little Colorado River, Arizona

Stone, Dennis M.; Gorman, Owen T.

doi:10.1674/0003-0031(2006)155[0123:ooehcg]2.0.co;2

Cited by 26 publications

(30 citation statements)

References 25 publications

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“…Under low turbidity conditions, Humpback Chub forage on material entrained in eddies (Valdez and Ryel 1995). As turbidity increases, nearshore habitats are increasingly used and Humpback Chub may become opportunistically piscivorous (Stone and Gorman 2006). In support, predation risk experiments which occurred concurrently to this study found that predation risk for juvenile fish in nearshore habitats was highest under moderate turbidity (mean = 165; range = 34-594 FTU) conditions (Dodrill 2012), and on two occasions Humpback Chub were observed foraging on tethered fish (M. J. Dodrill, personal observation).…”

Section: Discussionsupporting

confidence: 73%

“…These habitats are relatively invariant to discharge fluctuations, likely contributing to why habitat selection patterns were robust to changes in discharge (Valdez et al 2001;Korman et al 2004). Lastly, smaller size-classes (<180 mm) of Humpback Chub may be more reliant on nearshore habitats (Stone and Gorman 2006) and more affected by daily fluctuations in river stage. However, concurrent research from 2009 to 2011 indicated no apparent change in the growth rate, survival, and habitat selection of juvenile native fish in response to the steady flow release (Dodrill 2012;Finch 2012;Gerig 2012).…”

Section: Discussionmentioning

confidence: 99%

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Habitat Selection and Movement of Adult Humpback Chub in the Colorado River in Grand Canyon, Arizona, during an Experimental Steady Flow Release

Gerig

Dodrill

Pine

2014

N American J Fish Manag

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Effective conservation and restoration programs for many native riverine fish communities are highly dependent on regulated river operations developed by water managers. Successfully implementing river flows to meet human needs and minimize ecosystem impacts requires understanding the linkages between hydrology, physical habitat, and fish ecology. In the Colorado River within Grand Canyon, Arizona, altered river conditions following the construction of Glen Canyon Dam have contributed to the decline of Humpback Chub Gila cypha. In 2010, a management experiment was implemented to contrast the modified low fluctuating flow policy with an experimental steady flow release. We assessed habitat selection and movement of 30 adult Humpback Chub implanted with acoustic telemetry tags during 2 months of fluctuating flow followed by 2 months of steady flow. We found that telemetered Humpback Chub used eddies extensively while avoiding runs and were associated with intermediate depths and larger substrates. During both flow treatments, Humpback Chub exhibited small daily movements of about 100 m/d. No effect of the flow experiment was observed on Humpback Chub habitat selection or movement. However, nearshore habitat use by Humpback Chub increased with turbidity fluxes caused by tributary floods. Overall our results suggest that adult Humpback Chub habitat selection and movement may not be impacted by the current hydropower operations, but habitat use and spatial distribution are influenced by changes in turbidity which has changed greatly in the Colorado River since the completion of Glen Canyon Dam. Received February 1, 2013; accepted August 28, 2013 Published online January 17, 2014

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Habitat Selection and Movement of Adult Humpback Chub in the Colorado River in Grand Canyon, Arizona, during an Experimental Steady Flow Release

Gerig

Dodrill

Pine

2014

N American J Fish Manag

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“…One goal of the GCDAMP is population recovery of federally endangered humpback chub Gila cypha , a large‐bodied, morphologically distinct cyprinid endemic to the Colorado River basin whose largest population is in Grand Canyon. The reasons humpback chub populations in Grand Canyon are imperilled are unresolved but likely include negative interactions with non‐native fish (Coggins et al ., ; Yard et al ., ); loss of essential habitats due to flow, temperature and sediment input modifications (Converse et al ., ; Clarkson and Childs, ; Stone and Gorman, ); and non‐native parasites (Minckley, ; Choudhury et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Assessing Juvenile Native Fish Demographic Responses to a Steady Flow Experiment in a Large Regulated River

et al. 2015

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The Colorado River below Glen Canyon Dam, Arizona, is part of an adaptive management programme which optimizes dam operations to improve various resources in the downstream ecosystem within Grand Canyon. Understanding how populations of federally endangered humpback chub Gila cypha respond to these dam operations is a high priority. Here, we test hypotheses concerning temporal variation in juvenile humpback chub apparent survival rates and abundance by comparing estimates between hydropeaking and steady discharge regimes over a 3-year period (July 2009-July 2012. The most supported model ignored flow type (steady vs hydropeaking) and estimated a declining trend in daily apparent survival rate across years (99.90%, 99.79% and 99.67% for 2009, 2010 and 2011, respectively). Corresponding abundance of juvenile humpback chub increased temporally; open population model estimates ranged from 615 to 2802 individuals/km, and closed model estimates ranged from 94 to 1515 individuals/km. These changes in apparent survival and abundance may reflect broader trends, or simply represent inter-annual variation. Important findings include (i) juvenile humpback chub are currently surviving and recruiting in the mainstem Colorado River with increasing abundance; (ii) apparent survival does not benefit from steady fall discharges from Glen Canyon Dam; and (iii) direct assessment of demographic parameters for juvenile endangered fish are possible and can rapidly inform management actions in regulated rivers.

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“…However, fish components were never identified, which seemed counterintuitive given the findings of Kaeding and Zimmerman (1983), Kubly (1990), a stable isotope study that associated piscivory with humpback chub (Benenati et al 2002), and my observations of six humpback chub that expelled ingested fish parts upon light handling (Stone 1999). Moreover, when this technique was originally tested on 20 roundtail chub, there was no mention of any fish items being evacuated (Wasowicz and Valdez 1994); however, fish items were detected in 8% of roundtail chub dissected by Vanicek and Kramer (1969).…”

Section: Introductionmentioning

confidence: 87%

Differential Detection of Ingested Items Evacuated from GenusGilaCyprinids by Two Nonlethal Alimentary Tract Lavage Techniques

Stone

2004

Journal of Freshwater Ecology

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Two nonlethal alimentary tract lavage techniques were conducted on ten bonytail chub (Gila elegans, 21 1-241 mm TL) that had previously ingested 2-4 rainbow trout (Onchorynchus mykiss, 4 0 mm TL) to evaluate their capabilities of detecting piscivory in the field. Each fish was initially lavaged with water down its buccal cavity and out its anal vent using the Wasowicz and Valdez (W-V) technique and then immediately flushed in the opposite direction with the Baker and Fraser (B-F) method. Microscopic examination of evacuated material revealed only three identifiable rainbow trout scales and other assorted clumps of presumably well-digested body material. Overall, 30% of bonytail chub expelled rainbow trout scales andlor other body material during the initial W-V lavage, and 60% expelled material during the B-F flush. Dissections of four bonytail, seven humpback (G. cypha), and four roundtail chubs (G. robusta) revealed that their intestines were similarly curved and tapered to ~5 0 % of the anterior widths. Whereas the B-F method pushes ingested items backwards through the increasingly larger intestinal circumferences in these Gila fishes, it is more apt to retrieve greater quantities of food items. Food preference studies based on findings from a highly size-selective lavage technique will likely be biased in favor of smaller, less-digestible prey items, such as invertebrates with chitinous exoskeletons. Use of the B-F rather than W-V technique should lessen this bias.

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Ontogenesis of Endangered Humpback Chub (Gila cypha) in the Little Colorado River, Arizona

Cited by 26 publications

References 25 publications

Habitat Selection and Movement of Adult Humpback Chub in the Colorado River in Grand Canyon, Arizona, during an Experimental Steady Flow Release

Habitat Selection and Movement of Adult Humpback Chub in the Colorado River in Grand Canyon, Arizona, during an Experimental Steady Flow Release

Assessing Juvenile Native Fish Demographic Responses to a Steady Flow Experiment in a Large Regulated River

Differential Detection of Ingested Items Evacuated from GenusGilaCyprinids by Two Nonlethal Alimentary Tract Lavage Techniques

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