Humpback chub 

(Gila cypha)

5-Year Review: 

Summary and Evaluation 

U.S. Fish and Wildlife Service 

Upper Colorado River Endangered Fish Recovery Program 

Denver, Colorado 

2011 
ii 

TABLE OF CONTENTS 

1.0 GENERAL INFORMATION ..........................................................................................................1 

 1.1 Purpose of 5-year Reviews ..................................................................................................1 

 1.2 Reviewers .............................................................................................................................1 

 1.3 Methodology Used to Complete Review .............................................................................2 

 1.4 Background ..........................................................................................................................2 

 1.4.1 Federal Register Notice Citation Announcing Initiations of This Review ..............2 

 1.4.2 Listing History .........................................................................................................3 

 1.4.3 Associated Rulemakings ..........................................................................................3 

 1.4.4 Review History ........................................................................................................3 

 1.4.5 Species’ Recovery Priority Number at Start of 5-year Review ...............................3 

 1.4.6 Recovery Plan or Outline .........................................................................................4 

2.0 REVIEW ANALYSIS .....................................................................................................................5 

 2.1 Application of the 1996 Distinct Population Segment Policy .............................................5 

 2.2 Recovery Criteria .................................................................................................................5 

 2.2.1 Does the species have a final, approved recovery plan containing objective, 

measureable criteria? ...............................................................................................5 

 2.2.2 Adequacy of recovery criteria ..................................................................................6 

 2.2.2.1 Do the recovery criteria reflect the best available and most up-to-date 

information on the biology of the species and its habitat? .............................6 

 2.2.2.2 Are all of the 5 listing factors that are relevant to the species 

addressed in the recovery criteria? ..................................................................6 

 2.2.3 List the recovery criteria as they appear in the recovery plan, and discuss 

how each criterion has or has not been met, citing information ..............................6 

 2.3 Synthesis ............................................................................................................................19 

3.0 RESULT ........................................................................................................................................21 

 3.1 Recommended Classification.............................................................................................21 

 3.2 New Recovery Priority Number ........................................................................................21 

4.0 RECOMMENDATIONS FOR FUTURE ACTIONS ...................................................................21 

5.0 REFERENCES ..............................................................................................................................22 
iii 

LIST OF FIGURES 

FIGURES 

1. Estimated numbers of humpback chub adults in four of five populations of the Upper 

Colorado River Basin .......................................................................................................................8 

2. Estimated numbers of humpback chub adults (≥ 200-mm TL) in the Grand 

Canyon population of the Lower Colorado River System ...............................................................9 

LIST OF TABLES 

TABLE 

1. Summary of the downlisting demographic and recovery factor criteria by recovery unit 

basin and a determination if the criteria have been met, partially met or not met for 

analyzing whether humpback chub can be downlisted ..................................................................20 
1 

5-YEAR REVIEW 

Humpback chub/Gila cypha

1.0 GENERAL INFORMATION 

1.1 Purpose of 5-year Reviews 

The U.S. Fish and Wildlife Service (Service) is required by section 4(c)(2) of the 

Endangered Species Act (Act) to conduct a status review of each listed species at 

least once every 5 years. The purpose of a 5-year review is to evaluate whether or 

not the species’ status has changed since it was listed (or since the most recent 

5-year review). Based on the 5-year review, we recommend whether the species 

should be removed from the list of endangered and threatened species, be changed 

in status from endangered to threatened, or be changed in status from threatened 

to endangered. Our original listing as endangered or threatened is based on the 

species’ status considering the five threat factors described in section 4(a)(1) of 

the Act. These same five factors are considered in any subsequent reclassification 

or delisting decisions. In the 5-year review, we consider the best available 

scientific and commercial data on the species, and focus on new information 

available since the species was listed or last reviewed. If we recommend a change 

in listing status based on the results of the 5-year review, we must propose to do 

so through a separate rule-making process including public review and comment. 

1.2 Reviewers 

Lead Regional Office: Mountain-Prairie Region (6) 

Mike Thabault, Assistant Regional Director-Ecological Services, 303/236-4210 

Bridget Fahey, Chief of Endangered Species, 303/236-4258 

Seth Willey, Regional Recovery Coordinator, 303/236-4257 

Lead Field Office: 

Upper Colorado River Endangered Fish Recovery Program 

Thomas Chart, Program Director, 303/969-7322, ext. 226 

Cooperating Field Offices: 

Ecological Services Field Office, Grand Junction, Colorado 

Al Pfister, Assistant Field Supervisor, 970/243-2778 

Colorado River Fisheries Program, Grand Junction, Colorado 

To Be Announced, Field Supervisor, 970/245-9319, ext.19 

Ecological Services Field Office, Salt Lake City, Utah 

Larry Crist, Field Supervisor, 801/975-3330, ext. 126 

Ecological Services Field Office, Cheyenne, Wyoming 

Mark Sattelberg, Field Supervisor, 307/772-2374, ext. 34 
2 

Arizona Fishery Resources Office, Whiteriver, Arizona 

Stewart Jacks, Field Supervisor, 928/338-4288 

Lower Colorado River Coordinator, Phoenix, Arizona 

Sam Spiller, Coordinator, 602/242-0210, ext. 240 

Ecological Services Field Office, Phoenix, Arizona 

Steve Spangle, Field Supervisor, 602/242-0210, ext. 244 

California-Nevada Ecological Services Field Office, Reno, Nevada 

Ted Koch, Field Supervisor, 775/861-6331 

Cooperating Regional Office(s): 

Southwest Region (2) 

Michelle Shaughnessy, Assistant Regional Director-Ecological Services, 

505/248-6646 

Susan Jacobsen, Chief of Endangered Species, 505/248-6641 

Wendy Brown, Regional Recovery Coordinator, 505/248-6664 

Pacific Southwest Region (8) 

Larry Rabin, Deputy Division Chief for Listing, Recovery, and Environmental 

Contaminants, 916/414-6464 

1.3 Methodology Used to Complete the Review 

On April 18, 2007, we published a Notice of Review in the Federal Register

(72 FR 19549) soliciting any new information on the humpback chub that may 

have a bearing on its classification as endangered or threatened. Less than 

20 people/agencies provided comments. All substantive comments and issues 

raised were considered. This 5-year review was primarily written by the Upper 

Colorado River Endangered Fish Recovery Program Office with substantive 

contributions and review by cooperating field and regional offices. It summarizes 

and evaluates information provided in the recovery goals, current scientific 

research, and surveys related to the species. All pertinent literature and 

documents on file at the Upper Colorado River Endangered Fish Recovery 

Program Office were used for this review (see References section below for cited 

documents). Interviews with individuals familiar with humpback chub were 

conducted as needed to clarify or obtain specific information. 

1.4 Background 

1.4.1 FR Notice Citation Announcing Initiation of This Review: 

72 FR 19549 April 18, 2007.
3 

1.4.2 Listing History 

Original Listing 

FR notice: 38 FR 106 

Date listed: June 4, 1973 

Entity listed: Chub, humpback; Gila cypha

Classification: Endangered, rangewide 

1.4.3 Associated Rulemakings

59 FR 13374; March 21, 1994 - Critical Habitat Designated 

66 FR 58748; November 23, 2001 - Reopening of Public Comment on 

Draft Recovery Goals for Four Endangered Fishes of the Colorado River 

Basin 

67 FR 55270 55271; August 28, 2002 - Notice of Availability of Recovery 

Goals for Four Endangered Fishes of the Colorado River Basin 

1.4.4 Review History: Historic 5-year reviews for all species, including the 

humpback chub were initiated by the Service’s Washington, D.C., office 

in 1979, 1985, and 1991 (44 FR 29566, May 21, 1979; 50 FR 29901, 

July 22, 1985; 56 FR 56882, November 6, 1991). The species’ status also 

was considered in the 1990 recovery plan and 2002 recovery goals 

(Service 1990; 2002). 

1.4.5 Species’ Recovery Priority Number at Start of 5-year Review: The 

humpback chub has a high recovery priority number of 2C. Species with a 

high priority rank (1, 1C, 2, 2C) are those that are the most threatened and 

have the highest potential for recovery. The “C” identifies that there is the 

potential for conflicts between needed recovery actions and economic 

activities. 
4 

Degree of Threat Recovery Potential Taxonomy Priority Conflict

High 

High 

Monotypic Genus 1 1C 

Species 2 2C* 

Subspecies/DPS 3 3C 

Low 

Monotypic Genus 4 4C 

Species 5 5C 

Subspecies/DPS 6 6C 

Moderate 

High 

Monotypic Genus 7 7C 

Species 8 8C 

Subspecies/DPS 9 9C 

Low 

Monotypic Genus 10 10C 

Species 11 11C 

Subspecies/DPS 12 12C 

Low 

High 

Monotypic Genus 13 13C 

Species 14 14C 

Subspecies/DPS 15 15C 

Low 

Monotypic Genus 16 16C 

Species 17 17C 

Subspecies/DPS 18 18C 

The above ranking system for determining Recovery Priority Numbers was established in 1983 (48 FR 43098, 

September 21, 1983, as corrected in 48 FR 51985, November 15, 1983). 

1.4.6 Recovery Plan

Name of plan or outline: Humpback chub (Gila cypha) Recovery Goals: 

amendment and supplement to the Humpback Chub Recovery Plan. 

Date approved: August 1, 2002 

Dates of previous revisions, if applicable: September 19, 1990 
5 

2.0 REVIEW ANALYSIS 

 2.1 Application of the 1996 Distinct Population Segment Policy 

This section of the 5-year review is not applicable to this species because the 

humpback chub was not listed as a distinct population segment nor is there 

relevant new information for this species regarding the application of the distinct 

population segment policy. 

 2.2 Recovery Criteria 

Recovery plans provide guidance to the Service, States, and other partners and 

interested parties on ways to minimize threats to listed species, and on criteria that 

may be used to determine when recovery goals are achieved. There are many 

paths to accomplishing the recovery of a species and recovery may be achieved 

without fully meeting all recovery plan criteria. For example, one or more criteria 

may have been exceeded while other criteria may not have been accomplished. In 

that instance, we may determine that, over all, the threats have been minimized 

sufficiently, and the species is robust enough, to downlist or delist the species. In

other cases, new recovery approaches and/or opportunities unknown at the time 

the recovery plan was finalized may be more appropriate ways to achieve 

recovery. Likewise, new information may change the extent that criteria need to 

be met for recognizing recovery of the species. Overall, recovery is a dynamic 

process requiring adaptive management, and assessing a species’ degree of 

recovery is likewise an adaptive process that may, or may not, fully follow the 

guidance provided in a recovery plan. We focus our evaluation of species status 

in this 5-year review on progress that has been made toward recovery since the 

species was listed (or since the most recent 5-year review) by eliminating or 

reducing the threats discussed in the five-factor analysis. In that context, progress 

toward fulfilling recovery criteria serves to indicate the extent to which threat 

factors have been reduced or eliminated. 

There are three programs in the Colorado River Basin working to recover or 

conserve humpback chub populations: The Upper Colorado River Endangered 

Species Recovery Program and two conservation programs, the Glen Canyon 

Dam Adaptive Management Program and the Lower Colorado River 

Multi-Species Conservation Program. Each program has its own website that 

contains information about its respective program, projects and reports that were 

used to analyze the status of humpback chub.

 2.2.1 Does the species have a final, approved recovery plan containing 

objective, measurable criteria? 

 X Yes

 No 
6 

 2.2.2 Adequacy of recovery criteria. 

 2.2.2.1 Do the recovery criteria reflect the best available and most 

up-to-date information on the biology of the species and its 

habitat? 

 Yes

 X No 

We recommend revising the Service’s 2002 Humpback Chub 

Recovery Goals to incorporate new information on population 

dynamics. More specifically, the as-written Recovery Goal 

requirement that these populations always display positive 

recruitment (i.e., recruitment that is greater than adult mortality) 

contradicts the best available information that indicates these 

populations have and likely will experience fluctuations. 

 2.2.2.2 Are all of the 5 listing factors that are relevant to the species 

addressed in the recovery criteria (and is there no new 

information to consider regarding existing or new threats)? 

 X Yes

 No

 2.2.3 List the recovery criteria as they appear in the recovery plan, and 

discuss how each criterion has or has not been met, citing 

information: 

The current status of humpback chub is endangered. Only the downlisting 

criteria are considered in this 5-year status review to determine if status 

can be changed (downlisted) to threatened. The downlisting criteria 

consider both the demographics of humpback chub and criteria that 

address the threats to the species. Analysis of each criterion is provided in 

italics directly below the criterion. Recovery of the species is considered 

basin wide, where extant populations exist (including five populations in 

the the upper basin recovery unit and the Grand Canyon population in the 

lower basin recovery unit). The downlist recovery criteria are from the 

recovery goals (Service 2002), Section 5.3 Objective, Measurable 

Recovery Criteria (pp. 42–46): 

DEMOGRAPHIC DOWNLISTING CRITERIA FOR HUMPBACK CHUB 

Historic abundance of the humpback chub is unknown, but is surmised from various reports and 

collections that indicate the species currently occupies about 68% of its historic habitat of about 

756 km of river. Six self-sustaining populations of humpback chub are known to exist. Each of 

these populations consists of a discrete reproducing group of fish, with independent 
7 

stock-recruitment dynamics, and is geographically separated from other populations. Five of the 

populations occur in the upper basin recovery unit: 1) Black Rocks, Colorado River, Colorado; 

2) Westwater Canyon, Colorado River, Utah; 3) Yampa Canyon, Yampa River, Colorado; 

4) Desolation/Gray Canyons, Green River, Utah; and 5) Cataract Canyon, Colorado River, Utah 

(Service 1990). The only population in the lower basin recovery unit occurs in the mainstem 

Colorado River in Marble and Grand Canyons and the Little Colorado River. 

Upper Basin Recovery Unit Criterion 1a: Each of the five self-sustaining populations is 

maintained over a 5-year period, starting with the first point estimate acceptable to the Service, 

such that the trend in adult (age-4+; ≥ 200 mm TL) point estimates does not decline significantly. 

Status of Upper Basin Recovery Unit Criterion 1a. This criterion has not been met. 

Population models measure a variety of parameters, including probability of capture; these 

parameters provide a level of certainty and reliability to the Service for these estimates in 

determining acceptance. As a result, we can accept these estimates but do not consider the 

populations to be self-sustaining. A significant decline appears from the first adult abundance 

estimate to the most recent estimate for the populations in Black Rocks, Westwater Canyon and 

Desolation/Gray Canyons (FIGURE 1); 400 wild young-of-year Gila species were taken into 

captivity from the Yampa River population and 25 adults from Desolation/Gray population have 

been brought into captivity to preserve their genetic uniqueness (as recommended, Finney 2006 

and Badame 2008, respectively). Populations occurring in Yampa and Cataract Canyons are 

too small to monitor through mark-recapture analysis; therefore, catch-per-unit-effort 

information has been recommended to track the status for at least the Cataract Canyon 

population; juvenile and adult Gila spp. are monitored as a component of the fish community 

during nonnative fish removal for the Yampa River population. 
8 

Black Rocks

0

500

1000

1500

2000

2500

3000

3500

1996 1998 2000 2002 2004 2006 2008 2010

Estimated Number of Adults

Westwater Canyon

0

2000

4000

6000

8000

10000

12000

14000

16000

1996 1998 2000 2002 2004 2006 2008 2010

Estimated Number of Adults

Desolation-Gray Canyon

0

2000

4000

6000

8000

10000

2000 2001 2002 2003 2004 2005 2006 2007 2008

Estimated Number of Adults

Cataract Canyon

0

200

400

600

800

1000

1200

1400

1600

1800

2002 2003 2004 2005 2006

Estimated Number of Adults

FIGURE 1. Estimated numbers of humpback chub adults (≥ 200-mm TL) in 4 of 5 populations of the 

Upper Colorado River Basin. Error bars are 95% confidence intervals. The line at 2,100 represents the 

minimum viable population number; for core populations they need to exceed this level. Data from Black 

Rocks (McAda 2003a; 2007), Westwater Canyon (Elverud 2008), Desolation/Gray Canyons (P. Badame, 

Utah Division of Wildlife Resources, pers. comm.), and Cataract Canyon (Badame 2008). 

Upper Basin Recovery Unit Criterion 1b: Each of the five self-sustaining populations is 

maintained over a 5-year period, such that mean estimated recruitment of age-3 (150 to 

199 mm TL) naturally produced fish equals or exceeds mean annual adult mortality. 

Status of Upper Basin Recovery Unit Criterion 1b. This criterion has not been met. We do 

not consider these populations to be self-sustaining, likely as a result of poor recruitment. Too 

few juveniles are collected during population estimate sampling do to gear type being more 

selective for adults, i.e., larger fish; and other gear used to select juveniles has had limited 

success. 

Upper Basin Recovery Unit Criterion 2. One of the 5 populations (e.g., Black 

Rocks/Westwater Canyon or Desolation/Grey Canyons) is maintained as a core population such 

that each point estimate exceeds 2,100 adults (Note: 2,100 is the estimated MVP number for a 

self-sustaining population). 

Status of Upper Basin Recovery Unit Criterion 2. This criterion has not been met. A 

presumable core population of humpback chub at either Westwater Canyon/Black Rocks or 

Desolation/Grey Canyon does not exceed the 2,100 adults necessary to meet the criterion 

(FIGURE 1). 
9 

Lower Basin Recovery Unit Criterion 1a: The Grand Canyon population is maintained as a 

core over a 5-year period, starting with the first point estimate acceptable to the Service, such 

that the trend in adult (age-4+; ≥ 200 mm TL) point estimates does not decline significantly. 

Status of Lower Basin Recovery Unit Criterion 1a. This criterion has been partially met. 

Population estimates for humpback chub in Grand Canyon are based on an age-structured 

mark-recapture (ASMR) analysis that uses capture histories from PIT-tagged fish starting in 

1989 (FIGURE 2). These estimates are based on models that incorporate uncertainty in age 

assignment and a mortality rate of 0.13 for age-4+ fish (≥ 200 mm TL; Coggins et al. 2006a; 

2006b; Coggins 2008; Coggins and Walters 2009). Earliest estimates are based on small 

numbers of marks and recaptures and have wider confidence intervals than more recent 

estimates. These estimates show a decline in the population with the lowest estimate of between 

about 4,600 and 5,300 age-4+ fish in 2001. Recent estimates suggest that the population of 

adults may be stabilizing and improving after more than a decade of decline (U.S. Geological 

Survey 2006; 2007). Between 2001 and 2008, the numbers of adults appear to have increased to 

an estimated 7,650 adults. The ASMR analysis provides a level of certainty and reliability to the 

Service for these estimates in determining acceptance. As a result, we can accept these estimates 

for as far back as they are calculated and consider the population to be self-sustaining. 

FIGURE 2. Estimated numbers of humpback chub adults (≥ 200-mm TL) in the Grand Canyon 

population of the Lower Colorado River System. Error bars are a range of estimates from Monte 

Carlo simulations (Coggins and Walters 2009.) 
10 

Lower Basin Recovery Unit Criterion 1b: The Grand Canyon population is maintained as a 

core over a 5-year period, starting with the first point estimate acceptable to the Service, such 

that mean estimated recruitment of age-3 (150 to 199 mm TL) naturally produced fish equals or 

exceeds mean annual adult mortality. 

Status of Lower Basin Recovery Unit Criterion 1b. This criterion has been partially met. In 

2005, scientists also detected more juveniles (age-1 to age-3+) and young-of-year than previous 

years indicating good future recruitment. The increase in adult abundance appears to be driven 

by a gradual increase in recruitment since the mid to late 1990s. However, simulation results 

suggest that this apparent gradual increase in recruitment is quite possibly an artifact of ageing 

error causing recent strong cohorts to be incorrectly assigned to earlier brood-years. 

Lower Basin Recovery Unit Criterion 1c: The Grand Canyon population is maintained as a 

core over a 5-year period, starting with the first point estimate acceptable to the Service, such 

that each core population point estimate exceeds 2,100 adults (MVP). 

Status of Lower Basin Recovery Unit Criterion 1c. This criterion has been met. The 

estimate of adults in this population has never been below 4,600. A population of 7,650 means 

this core population exceeds the MVP of 2,100. We can accept these estimates for as far back as 

they are calculated and consider the population to be self-sustaining.

RECOVERY FACTOR DOWNLISTING CRITERIA FOR HUMPBACK CHUB TO 

MINIMIZE OR REMOVE THREATS TO THE SPECIES 

UPPER BASIN RECOVERY UNIT

Factor A—Adequate habitat and range for recovered populations provided. 

Streamflow regulation and associated habitat modification are primary threats to humpback chub 

populations. Reservoir inundation, cold-water releases from dams, streamflow alteration, 

changes in channel geomorphology, and modification of sediment transport have impacted 

habitat of the native Colorado River fishes, including the humpback chub. Dams were 

considered a major threat to the humpback chub at the time of listing; however, construction of 

new dams affecting occupied habitat ceased nearly 4 decades ago. Changes in channel 

geomorphology of habitat occupied by humpback chub are not extensive because most habitat 

occurs in rocky canyon-confined reaches with low susceptibility to geomorphic modification. 

Maintenance of streamflow is important to the ecological integrity of large western rivers. Flow 

recommendations have been developed for some river systems in the Upper Colorado River 

Basin that identify and describe flows with the necessary magnitude, frequency, duration, and 

timing to benefit the endangered fish species (Modde et al. 1999; McAda 2003; Muth et al. 

2000). 
11 

Criterion 1. Flow regimes to benefit humpback chub populations in the upper Colorado, 

Green, and Yampa Rivers should be identified, implemented, evaluated, and 

revised, such that: 

a. Adequate spawning habitat and appropriate spawning cues (e.g., flow patterns 

and water temperatures) are available to maintain self-sustaining populations, 

as reflected by downlisting demographic criteria. 

b. Adequate nursery habitat is available to maintain self-sustaining populations, 

as reflected by downlisting demographic criteria. 

c. Adequate juvenile and adult habitat (e.g., cover, resting, and feeding areas) is 

available to maintain self-sustaining populations, as reflected by downlisting 

demographic criteria. 

Status of Criterion 1. Criterion 1 has been partially met. Flow 

recommendations have been developed for the Green River (Muth et al. 2000); 

Yampa River (Modde et al. 1999), and upper Colorado River (McAda 2003b). 

These flow recommendations are primarily for Colorado pikeminnow and 

razorback sucker, but are believed to benefit the humpback chub in sections 

below the reaches of interest. These flow recommendations are still being 

evaluated and modified annually through adaptive management. 

Factor B—Protection from overutilization for commercial, recreational, scientific, or 

educational purposes. 

Overutilization of humpback chub for commercial, recreational, scientific, or educational 

purposes is not currently considered a threat to the species. Humpback chub have no commercial 

or recreational value and are not sought by commercial fishermen or anglers. Collection of 

humpback chub for scientific or educational purposes is regulated by the Service under the Act. 

Criterion 2. Overutilization of humpback chub for commercial, recreational, scientific, or 

educational purposes reevaluated and, if necessary, actions identified to ensure 

adequate protection. 

Status of Criterion 2. Criterion 2 has been met. No commercial or recreational 

activities exist. Educational activities are minimal and do not threaten humpback 

chub. Scientifically, reduced survival of adult humpback chub as a result of 

handling has not been proven, and delayed mortality due to sampling has not 

been demonstrated. 

Factor C—Adequate protection from diseases and predation. 

Diseases and parasites currently are not considered to be significant in the decline of the 

humpback chub in the upper basin. 
12 

The threat of predation by nonnative fishes on humpback chub has been recognized in two 

populations in the upper basin. Channel catfish (Ictalurus punctatus) are the principal predator 

of humpback chub in Desolation/Gray Canyons (Chart and Lentsch 2000) and Yampa Canyon 

(Upper Colorado River Endangered Fish Recovery Program 1999). Control of the release and 

escapement of nonnative fishes into the mainstem, floodplain, and tributaries is a necessary 

management action to stop the introduction of new fish species into occupied habitats and to 

thwart periodic escapement of highly predaceous nonnatives from riverside features. Annual 

flooding of the river can inundate riverside ponds potentially containing large numbers of green 

sunfish (Lepomis cyanellus), black bullhead (Ameiurus melas), largemouth bass (Micropterus 

salmoides), and other nonnative fishes that may escape to the river during high flows (Valdez 

and Wick 1983). Three management actions are identified to reduce the threat of nonnative 

fishes: high spring flows, nonnative fish control strategies, stocking agreements. Active control 

programs should be implemented or continued (as needed) for problematic nonnative fishes in 

Yampa Canyon and Desolation/Gray Canyons. 

Criterion 3. Effects of diseases and parasites on humpback chub populations should be 

reevaluated and, if necessary, actions identified to ensure adequate protection. 

Status of Criterion 3. Criterion 3 has not been met. The effects of disease and 

parasites on humpback chub populations have not been re-evaluated.

Criterion 4. Procedures should be developed, implemented, evaluated, and revised for 

stocking nonnative fish species in the Upper Colorado River Basin to minimize 

negative interactions between nonnative fishes and humpback chub. 

Status of Criterion 4. Criterion 4 has been met. Procedures were developed in 

1996 and modified in 2009 (Service 1996; 2009). The Procedures distinguish 

between stocking nonnative salmonids and non-salmonids and have specific 

requirements for stocking locations related to their proximity to critical habitat.

Criterion 5. Channel catfish control programs should be developed and implemented to 

identify levels of control that would minimize predation on humpback chub in 

Yampa Canyon and Desolation/Gray Canyons. 

Status of Criterion 5. Criterion 5 has been partially met. A level of control of 

channel catfish has been identified, but superceded by actions to remove or 

minimize predation and competition effects of small mouth bass (Fuller 2006; 

Haines and Modde 2007). The level of channel catfish control needs to be 

evaluated and reviewed.

Factor D—Adequate existing regulatory mechanisms. 

Implementation of regulatory mechanisms is necessary for recovery of the humpback chub and 

to ensure long-term conservation of the species. After removal from the list of species protected 

by the Act, the humpback chub and its habitat will continue to receive consideration and some 
13 

protection through the following Federal laws and related state statutes: National Environmental 

Policy Act; Clean Water Act; Organic Act; and Fish and Wildlife Coordination Act. 

The need for conservation plans and agreements was identified to provide reasonable assurances 

that recovered humpback chub populations will be maintained. 

Criterion 6. Regulatory mechanisms determined adequate for legal protection of adequate 

habitat are identified. 

Status of Criterion 6. Criterion 6 has been partially met. Filing for legal rights 

to protect water for fish would be junior to the legal rights of others who have 

already claimed water for irrigation and power. Utah is currently reviewing the 

water rights from Flaming Gorge and how they may be modified for fish 

protection. Other legal options that could be employed are leasing water 

(Steamboat Reservoir) or contractual commitments (Wolford and Elkhead 

Reservoirs). In addition, 60,000 acre-feet on the upper Colorado River from the 

Historic Users Pool (reservoir projects built prior to the Recovery Program, i.e., 

1988) are used to maintain river flows in the 15-mile reach (from Palisade to the 

confluence of the Gunnison River) as written in a programmatic biological 

opinion. 

Criterion 7. Elements of conservation plans identified that are necessary to provide for the 

long-term management and protection of humpback chub populations. 

Status of Criterion 7. Criterion 7 has not been met. Conservation plans and 

the necessary elements have not been developed. 

Factor E—Other natural or manmade factors for which protection has been provided. 

Humpback chub, bonytail (Gila elegans), and roundtail chub (Gila robusta) are sympatric 

Colorado River mainstem species with substantial evidence of introgressive hybridization 

(Dowling and DeMarais 1993). 

The potential role of pesticides and pollutants in suppressing populations of Gila were discussed 

by Wick et al. (1981). Potential spills of hazardous materials threaten some populations of 

humpback chub. All States have hazardous-materials spills emergency-response plans that 

provide a quick cleanup response to accidental spills. 

Criterion 8. State and Federal hazardous-materials spills emergency-response plans should be 

reviewed and modified to ensure adequate protection for humpback chub 

populations from hazardous-materials spills. 

Status of Criterion 8. Criterion 8 has not been met. The hazardous-materials 

spills emergency-response plans have not been reviewed or modified. 
14 

Criterion 9. Measures should be identified to minimize the risk of hazardous-materials spills 

in Black Rocks and Westwater Canyon from transport of materials along the 

adjacent railway. 

Status of Criterion 9. Criterion 9 has not been met. No measures have been 

identified to minimize the risk of hazardous materials spills in Black Rocks and 

Westwater Canyon from materials transported along railway. 

Criterion 10. Locations of all petroleum-product pipelines within the 100-year floodplain of 

critical habitat should be identified and the need for emergency shut-off valves 

assessed. 

Status of Criterion 10. Criterion 10 has been partially met. Although some 

progress has been made in locating all petroleum-product pipelines, 

determination of emergency shut off valves has not been assessed. New pipelines 

crossing rivers are required to have shut-off valves.

LOWER BASIN RECOVERY UNIT

Factor A—Adequate habitat and range for recovered populations provided. 

An Environmental Impact Statement in 1995, with a Record of Decision in 1996, established 

releases from Glen Canyon Dam that will be evaluated through adaptive management to protect 

resources of the Colorado River through Grand Canyon (U.S. Department of the Interior 1995). 

Criterion 1. Life stages and habitats of humpback chub in the mainstem Colorado River 

should be identified and the relationship between individuals in the mainstem and 

the Little Colorado River should be determined. 

Status of Criterion 1. Criterion 1 has been met. Greatest movement of 

humpback chub has been reported from Grand Canyon, primarily because adults 

from the mainstem annually ascend the Little Colorado River to spawn (Valdez 

and Ryel 1995; Paukert et al. 2006). Average movement of 401 PIT-tagged fish 

marked in the mainstem and recaptured in the Little Colorado River was 7.2 km 

(range, 0.08 to 34.1 km). However, most of these fish returned to the mainstem 

with remarkable fidelity to mainstem locales. Of 60 PIT-tagged fish consecutively 

captured in the mainstem, then the Little Colorado River, and again in the 

mainstem, 54 (90%) returned to within 2 km of their original mainstem locale; 31 

(52%) were recaptured within 0.5 km; and 10 (17%) were recaptured within 

0.1 km. No significant difference in movements was noted between male and 

female humpback chub. Fish moving from the mainstem to the Little Colorado 

River and back to the mainstem tended to be larger fish than those remaining in 

the Little Colorado River (81% were >300 mm TL). Paukert et al. (2006) found 

similar fidelity with several fish moving more than 154 km throughout Grand 

Canyon between capture and recapture.
15 

Criterion 2. Operations of Glen Canyon Dam to benefit humpback chub in the Colorado River 

through Grand Canyon should be continued and a flow regime to benefit 

humpback chub in the Little Colorado River should be identified, implemented, 

evaluated, and revised, such that: 

a. Adequate spawning habitat and appropriate spawning cues (e.g., flow patterns 

and water temperatures) are available to maintain a self-sustaining population, 

as reflected by downlisting demographic criteria in section 5.3.1.1.2. 

b. Adequate nursery habitat is available to maintain a self-sustaining population, 

as reflected by downlisting demographic criteria in section 5.3.1.1.2. 

c. Adequate juvenile and adult habitat (e.g., cover, resting, and feeding areas) is 

available to maintain a self-sustaining population, as reflected by downlisting 

demographic criteria in section 5.3.1.1.2. 

Status of Criterion 2. Criterion 2 has been partially met. In 2008, the Service 

issued a new biological opinion on the operation of Glen Canyon Dam. That 

opinion replaced the 1995 opinion and determined that implementation of the 

March 2008 high flow test and the 5-year implementation of Modified Low 

Fluctuating Flows with steady releases in September and October was not likely 

to jeopardize the continued existence of the humpback chub and was not likely to 

destroy or adversely modify designated critical habitat. The 2008 biological 

opinion contained conservation measures that include: 1) a reconsultation 

trigger if the population of adult humpback chub (≥200 mm TL) in Grand Canyon 

declines significantly, or, if in any single year, based on the ASMR model 

(Coggins 2008), the population drops below 3,500 adult fish within the 95% 

confidence interval; 2) development of a Comprehensive Plan for the 

Management and Conservation of Humpback Chub in Grand Canyon; 

3) humpback chub translocations; 4) implementation of nonnative fish control; 

5) humpback chub nearshore ecology study; 6) monthly flow transition study; 

7) creation of a humpback chub refuge population; and 8) initiation of a Little 

Colorado River watershed plan. As the result of a lawsuit filed by the Grand 

Canyon Trust, a Federal Court Judge ruled that the 2008 opinion was a 

departure from the Service’s prior position and ordered the Service to revise the 

opinion by October 31, 2009. The opinion was adequately explained and the 

conservation measures in the opinion were accepted by the court on March 30, 

2011. 

The Little Colorado River Watershed Coordinating Council was formed in 2007 

to help coordinate water management activities within the Little Colorado River. 

The Council has a Water Quality Improvement Grants program that provides 

interested parties with Federal grants to improve water quality in the Little 

Colorado River watershed. 

Criterion 3. Effects and feasibility of a temperature control device for Glen Canyon Dam to 

increase water temperatures in the mainstem Colorado River through Grand 
16 

Canyon that would allow for range expansion of humpback chub should be 

determined. 

Status of Criterion 3. Criterion 3 has been met. A risk assessment and scoping 

environmental assessment for a temperature control device on the penstocks at 

Glen Canyon Dam have been completed (U.S. Bureau of Reclamation 2004).

Factor B—Protection from overutilization for commercial, recreational, scientific, or 

educational purposes. 

Overutilization of humpback chub for commercial, recreational, scientific, or educational 

purposes is not currently considered a threat to the species. Humpback chub have no commercial 

or recreational value and are not sought by commercial fishermen or anglers. Collection of 

humpback chub for scientific or educational purposes is regulated by the Service under the Act. 

Criterion 4. Overutilization of humpback chub for commercial, recreational, scientific or 

educational purposes should be reevaluated and, if necessary, actions identified to 

ensure adequate protection. 

Status of Criterion 4. Criterion 4 has been met. No commercial, recreational 

or educational activities exist. Scientifically, reduced survival of adult humpback 

chub as a result of handling has not been proven, and delayed mortality due to 

sampling has not been demonstrated. Hunt (2008) concluded trammel netting as 

a sampling technique should be avoided at temperatures at or above 20oC. The 

effects appeared much worse for hatchery-produced razorback sucker and 

bonytail than for wild roundtail chub. It’s assumed that wild humpback chub 

would be similar to wild roundtail chub. 

Factor C—Adequate protection from diseases and predation. 

Meretsky et al. (2000) hypothesized that an observed decline in condition of adult humpback 

chub in Grand Canyon was a result of recent infestation by the internal Asian tapeworm 

(Bothriocephalus acheilognathi). 

Criterion 5. An Asian tapeworm control program should be developed and implemented in the 

Little Colorado River to identify levels of control that will minimize the negative 

effects of parasitism on the humpback chub population. 

Status of Criterion 5. Recovery Factor Criterion 5 has been met. Ward (2007) 

developed protocols for treating humpback chub for Asian tapeworm. Arizona 

Game and Fish Department is implementing those protocols (Clark et al. 2008). 

The threat of predation by nonnative fishes on humpback chub has been 

recognized in Grand Canyon population. Brown trout (Salmo trutta), channel 

catfish, black bullhead, and rainbow trout (Oncorhynchus mykiss) have been 

identified as principal predators of juvenile humpback chub, with estimates that 
17 

suggest loss of complete year classes to predation (Marsh and Douglas 1997; 

Valdez and Ryel 1997). Studies from the lower Colorado River through Grand 

Canyon (Hoffnagle et al. 1999; Valdez et al. 2001) showed reductions in densities 

of small-bodied species of fish (e.g., fathead minnow [Pimephales promelas], red 

shiner [Cyprinella lutrensis], plains killifish [Fundulus zebrinus]) following high 

flows. High releases from Glen Canyon Dam in 1996 (Hoffnagle et al. 1999; 

Valdez et al. 2001) and in 2000 (Trammell et al. 2001) significantly reduced 

numbers of red shiner, fathead minnow, and plains killifish with no decline in 

native species. A strong year class of humpback chub in Grand Canyon in 1993 

followed high early spring-runoff flows from the Little Colorado River, and was 

attributed to cleansing of spawning gravels and short-term reduction in nonnative 

fishes (Gorman 1994). 

Citerion 6. Procedures should be developed, implemented, evaluated, and revised for 

stocking and to minimize escapement of nonnative fish species into the Colorado 

River and its tributaries through Grand Canyon to minimize negative interactions 

between nonnative fishes and humpback chub. 

Status of Criterion 6. Criterion 6 has not been met. No procedures have been 

developed.

Criterion 7. Rainbow trout, channel catfish, black bullhead, and common carp control 

programs should be developed and implemented to identify levels of control that 

will minimize predation on humpback chub in the Little Colorado River. 

Status of Criterion 7. Criterion 7 has been partially met. The percentage of 

nonnative fishes in the Little Colorado River remains at low levels (Ward and 

Persons 2007). The number of fathead minnows has increased since 1994, 

although trends are difficult to assess due to high variability in catch rate 

between years. Ward and Persons (2007) concluded, if the mainstem Colorado 

River continues to be warm, fathead minnow and red shiner may be able to 

become established in the mainstem and invade the Little Colorado River between 

flood events much more quickly. Black bullhead and channel catfish catch rates 

have been highly variable in recent years, although they have been increasing 

since 2002. Common carp do not show any trends; however, adult common carp 

are not very susceptible to capture in hoop nets. 

Criterion 8. Brown trout and rainbow trout control programs should be developed and 

implemented to identify levels of control that will minimize predation on 

humpback chub in the Colorado River through Grand Canyon. 

Status of Criterion 8. Criterion 8 has been partially met. Mechanical removal 

of brown trout and rainbow trout around the confluence occurred from 

2003-2008. Although a declining catch rate was identified over the 5-year period 

an identified level of control has not been determined.
18 

Factor D—Adequate existing regulatory mechanisms. 

Implementation of regulatory mechanisms is necessary for recovery of the humpback chub and 

to ensure long-term conservation of the species. After removal from the list of species protected 

by the Act, the humpback chub and its habitat will continue to receive consideration and some 

protection through the following Federal laws and related state statutes: National Environmental 

Policy Act; Clean Water Act; Organic Act; and Fish and Wildlife Coordination Act. 

The need for conservation plans and agreements was identified to provide reasonable assurances 

that recovered humpback chub populations will be maintained. 

Criterion 9. Mechanisms determined adequate for legal protection of adequate habitat in the 

mainstem Colorado River through Grand Canyon and the Little Colorado River 

should be developed. 

Status of Criterion 9. Criterion 9 has been met. The Grand Canyon Protection 

Act along with “law of the river,” including interstate compacts, provide flows 

through Grand Canyon to deliver to lower basin states and benefit the ecosystem 

overall. The Glen Canyon Dam Adaptive Management Work Group through its 

Technical Work Group and the biological opinion for the reoperation of Glen 

Canyon Dam is the mechanism in which these flows are protected and provided. 

A Little Colorado River watershed study is a basin-wide effort to define the 

problems, identify solutions and options related to protecting and increasing 

water supplies, preserve/enhance a more natural environment, and improve the 

health of the watershed. There are multiple jurisdictions over the water resources 

that are working to develop a coordinated management plan to optimize the water 

resources to meet the water needs. 

Criterion 10. Elements of conservation plans are identified that are necessary to provide for the 

long-term management and protection of humpback chub populations. 

Status of Criterion 10. Criterion 10 has not been met. Conservation plans and 

the necessary elements have not been developed. 

Factor E—Other natural or manmade factors for which protection has been provided. 

The potential role of pesticides and pollutants in suppressing populations of Gila were discussed 

by Wick et al. (1981). Potential spills of hazardous materials threaten some populations of 

humpback chub. All States have hazardous-materials spills emergency-response plans that 

provide a quick cleanup response to accidental spills. A preventive measure may include 

filtration systems in case of accidental spills of hazardous materials at the Cameron bridge 

crossing above occupied habitats. 

Criterion 11. State and Federal hazardous-materials spills emergency-response plans should be 

reviewed and modified to ensure adequate protection for humpback chub 

populations from hazardous-materials spills. 
19 

Status of Criterion 11. Criterion 11 has not been met. The 

hazardous-materials spills emergency-response plans have not been reviewed or 

modified. 

Criterion 12. Measures should be identified to minimize the risk of hazardous-materials spills 

from transport of materials along U.S. Highway 89 at and near the two Cameron 

bridges spanning the Little Colorado River. 

Status of Criterion 12. Criterion 12 has not been met. No measures have been 

identified to minimize the risk of hazardous materials spills in along 

U.S. Highway 89 and near the Cameron bridge spanning the Little Colorado 

River from materials transported along roadway. 

 2.3 Synthesis

Recovery is based on reduction or removal of threats and improvement of the 

status of a species during the period in which it is listed, and not just from the 

time a listed species is proposed for reclassification. Environmental conditions 

and the structure of populations change over time, and threats recognized at 

listing or in subsequent recovery plans may no longer be directly applicable when 

reclassification is considered. Management actions and tasks identified for listed 

species are expected to minimize or remove threats and improve the species’ 

status. 

Recovery is achieved when management actions and associated tasks have been 

implemented and/or completed to allow genetically and demographically viable, 

self-sustaining populations to thrive under minimal ongoing management and 

investment of resources. Achievement of recovery does not mandate returning a 

species to all or a significant portion of its historic range, nor does it mandate 

establishing populations in all possible habitats, or everywhere the species can be 

established or reestablished. 

At the time of listing, habitat losses were documented but the threats to humpback 

chub were poorly understood and distribution and abundance of the species were 

not well known. The decline of the species was probably a combination of 

threats, including direct loss of habitat and changes in flow and temperature. In 

addition, interaction with nonnative fish may have had a decimating effect in 

waters not affected by dams. Humpback chub is adapted to life in deep, canyonbound reaches of the Green, Colorado, and Little Colorado Rivers. 

Recovery of humpback chub is considered basinwide with the basin being 

separated into an upper basin and lower basin recovery unit. The analysis above 

of the demographic criteria has shown: 1 of the 6 downlisting demographic 

sub-criteria has been met, 2 have been partially met, and 3 have not been met 

(TABLE 1). From the above list of recovery factor downlisting criteria in the 

upper basin: 2 of the 10 have been met; 4 have been partially met, and 4 have not 

been met. In the lower basin: 2 of the 12 downlisting recovery factor criteria 
20 

have been met; 6 have been partially met, and 4 have not been met. Although the 

category “has been partially met” is identified, this is only to reflect that some 

progress is being made on that particular criterion. Since the majority of 

demographic (5 out of 6) and recovery factor dowlisting criteria (4 out of 22) have 

not been met, no change in the endangered status of humpback chub is 

recommended. The definition of endangered applies here until the demographic 

criteria are met and the threats minimized or removed. 

TABLE 1. Summary of the downlisting demographic and recovery factor criteria by 

recovery unit basin and a determination if the criteria have been met, partially met or 

not met for analyzing whether humpback chub can be downlisted. 

CRITERIA FOR DOWNLISTING 

HAS BEEN 

MET 

HAS BEEN 

PARTIALLY MET 

HAS NOT 

BEEN MET

Demographic

Upper Colorado River Subbasin 1a, 1b, 2 

Lower Colorado River Subbasin 1c 1a, 1b 

Upper Basin Recovery Factors

Recovery Factor A 1 

Recovery Factor B 2 

Recovery Factor C 4 5 3 

Recovery Factor D 6 7 

Recovery Factor E 10 8, 9 

Lower Basin Recovery Factors

Recovery Factor A 1, 3 2 

Recovery Factor B 4 

Recovery Factor C 5 7, 8 6 

Recovery Factor D 9 10 

Recovery Factor E 11, 12 
21 

3.0 RESULTS 

3.1 Recommended Classification

 X No change is needed 

3.2 New Recovery Priority Number: We do not recommend a change in the 

Recovery Priority Number. The degree of threat is high, with a high degree of 

recovery potential representing a species, which falls under the 2C category for a 

recovery priority number according to the “Endangered and threatened species 

listing and recovery priority guidance” (48 FR 43098). 

4.0 RECOMMENDATIONS FOR FUTURE ACTIONS 

The Upper Colorado River Endangered Fish Recovery Program along with the Glen Canyon 

Dam Adaptive Management Program (a conservation program to restore the Grand Canyon 

ecosystem) continue working to meet the recovery factor criteria to minimize or remove threats 

to the humpback chub in their respective recovery units. These programs develop annual work 

plans through adaptive management (Recovery Implementation Program Recovery Action Plan 

and Annual Budget and Work Plan, respectively), to minimize and remove threats to the 

humpback chub and thus achieve the recovery factor criteria. By meeting these recovery factor 

criteria, the demographics of the species should improve. The improvement in demographics is 

evidenced by the lower basin having 75% (8 out of 12) of the recovery factor criteria met or 

partially met, along with an increasing trend in adult abundance. In particular, the nonnative fish 

control actions that have been taken and the increased water temperatures as a result of lower 

Lake Powell levels have improved the status of the species in the lower basin recovery unit. 

The recovery goals are currently being revised based on new information since their publication 

in 2002. Subsequently, the recovery plans will be revised. 

Uncertainty surrounding the effects of climate change to the humpback chub should be 

considered for each of the threats as those impacts are realized. For example, the potential for 

alteration of flows in the basin as a result of climate change should at least be mentioned in the 

recovery goals. Climate change could have large impacts on the basin’s aquatic ecosystem, 

resulting in (but not limited to): 

 Change in the timing of peak flows due to altered snowmelt patterns; 

 Change in runoff peaks due to increased inter-annual variation in snowpack formation; and 

 Change in water temperatures due to altered air temperatures. 

Not only would climate change affect the ecology of the species because of the factors listed 

above, but it also would greatly affect the management of the programs through changes in 

politics and economics, such as: 
22 

 Greater evaporation losses in the larger reservoirs may reduce flexibility of operations; and 

 Drier conditions in the basin may cause irrigators to call on their water rights more often or 

request more water rights. 

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24 

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