Status and Trends of the Endangered Colorado Squawfish in the Upper Colorado River

Osmundson, D. B.; Burnham, Kenneth P.

doi:10.1577/1548-8659(1998)127<0957:satote>2.0.co;2

Cited by 40 publications

(49 citation statements)

References 26 publications

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“…Direct enumeration of fish populations is not feasible in turbid rivers, and removal estimates are unreliable because of the difficulty of blocking reaches of large rivers to meet the model assumption of no migration. Instead, closed-population, multiple mark-recapture estimators (Otis et al 1978;Burnham et al 1987;Chao 1989;Osmundson and Burnham 1998) are recommended for deriving population point estimates and to guide development of sampling designs that conform to these models. The accuracy and precision of each point estimate will be assessed by the Service in cooperation with the respective recovery or conservation programs, and in consultation with investigators conducting the point estimates and with qualified statisticians and population ecologists.…”

Section: Demographic Criteria and Monitoringmentioning

confidence: 99%

Razorback sucker transbasin movement through Lake Powell, Utah

Durst

Francis

2016

The Southwestern Naturalist

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Section: Demographic Criteria and Monitoringmentioning

confidence: 99%

Razorback sucker transbasin movement through Lake Powell, Utah

Durst

Francis

2016

The Southwestern Naturalist

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“…Fish population studies by Osmundson and Burnham [1996] indicate that there are perhaps only about 600 Colorado squawfish remaining in the upper Colorado River (defined here as the reach upstream from the confluence with the Green River, Utah, to Palisade, Colorado). The largest concentration of adult Colorado squawfish in the upper Colorado River is found in reaches near Grand Junction.…”

Section: Introductionmentioning

confidence: 99%

Geomorphology and endangered fish habitats of the upper Colorado River: 2. Linking sediment transport to habitat maintenance

Pitlick¹,

Steeter²

1998

Water Resources Research

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Abstract. Alluvial reaches of the Colorado River near Grand Junction, Colorado, provide important habitat for the endangered Colorado squawfish. This paper examines recent changes in the geomorphology of the Colorado River and addresses the question of what can be done to improve existing fish habitats. Observations of channel change during periods of above-average runoff from 1993 through 1995 indicate minor scour and fill of the main channel, but more significant scour and enlargement of side-channel and backwater habitats and flushing of fine sediment from the bed. Modeled relations between discharge and dimensionless shear stress ** indicate that the threshold of bed load transport (** = 0.03) occurs at about half the bank-full discharge; these flows are exceeded about 26 days per year on average. The bank-full discharge produces an average ** of 0.047 and is exceeded about 8 days per year. The width and depth of the channel thus appear to be set by a discharge that produces an average boundary shear stress of --•1.5 times greater than the critical shear stress. The effective discharge is slightly less than the bank-full discharge, and approximately 80% of the total sediment load is carried by the highest 10% of all discharges. In this paper we develop criteria for flows that will maintain or improve habitats used by Colorado squawfish. Given the wide range in habitat characteristics, we believe that the processes of habitat formation and maintenance in the upper Colorado River are best studied using a broad-based geomorphic approach. Accordingly, we formulated three objectives for this study.

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“…Suppression of the natural flood regime can result in disruption of spawning behaviors, a loss of access to rearing habitat for juvenile fish, and reduced recruitment (Osmundson and Burnham 1998;Modde et al 2001;Bunn and Arthington 2002). For fish species such as Oregon chub that presumably rely on floods for dispersal, alteration of the natural hydrologic regime often results in population isolation and loss of gene flow.…”

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confidence: 99%

Analyses of Genetic Variation in Populations of Oregon Chub, a Threatened Floodplain Minnow in a Highly Altered Environment

et al. 2012

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The Oregon chub Oregonichthys crameri is a small floodplain minnow endemic to the Willamette River basin of western Oregon. Historically the species was widely abundant and probably relied on periodic floods for dispersal and genetic exchange among populations. The species has declined substantially in the past 100 years due to habitat alterations and the introduction of nonnative species and is currently listed as threatened under the U.S. Endangered Species Act. Information on the level of genetic variation within and among populations did not exist when the species was listed or when a recovery plan was being developed. In this study, we used a suite of nine microsatellite loci to characterize genetic variation within and among 16 sampling locations and provide information to help guide future recovery efforts. Even though many locations are presently isolated from one another, we observed relatively high levels of genetic variation within collections. Temporal samples revealed that the levels of genetic variation were stable over time despite fluctuations in abundance. Estimates of effective population size (Ne) for three sampling locations ranged from approximately 120 to 220 and suggest that there is no immediate threat from inbreeding or genetic drift. We observed a significant level of genetic variation among sampling locations (global FST = 0.078) and significant differences in allele frequencies among all sampling locations. Our results suggest that the different locations represent distinct populations of Oregon chub and that greater levels of gene flow occur among populations within the Santiam and Middle Fork Willamette River subbasins. The information presented in this study will help guide Oregon chub recovery efforts, including the refinement of recovery areas and future population introduction efforts, and will help address the challenge of managing populations largely in isolation from one another in order to minimize threats from nonnative species.

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Status and Trends of the Endangered Colorado Squawfish in the Upper Colorado River

Cited by 40 publications

References 26 publications

Razorback sucker transbasin movement through Lake Powell, Utah

Razorback sucker transbasin movement through Lake Powell, Utah

Geomorphology and endangered fish habitats of the upper Colorado River: 2. Linking sediment transport to habitat maintenance

Analyses of Genetic Variation in Populations of Oregon Chub, a Threatened Floodplain Minnow in a Highly Altered Environment

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