U.S. Bureau of Reclamation Upper Colorado Region 

THE POTENTIAL OF HABITAT FOR THE 

RAZORBACK SUCKER IN THE LOWER GRAND CANYON 

AND COLORADO RIVER INFLOW TO LAKE MEAD 

A SCIENCE PANEL REPORT 

Salt Lake City, Utah Final Report – April 2012
Cover Photo: 

Aerial view of lower Grand Canyon (R. Valdez, June 24, 1992). 

Disclaimer: 

The opinions and recommendations expressed in this report are those of the author and the 

Science Panel and do not necessarily reflect the views of the U.S. Bureau of Reclamation or any 

other agency or organization. The use or mention of trade names, commercial products, or firms 

and businesses does not constitute endorsements or recommendations for use. 

Recommended Citation: 

Valdez, R.A., C. McAda, G. Mueller, D. Ryden, and M. Trammell. 2012. The potential of habitat 

for the razorback sucker in the lower Grand Canyon and Colorado River inflow to Lake Mead: A 

Science Panel Report, Report Number 2. Final Report prepared by SWCA, Environmental 

Consultants for U.S. Bureau of Reclamation, Upper Colorado Region, Salt Lake City, Utah. 

i 
Report Number 2 

THE POTENTIAL OF HABITAT FOR THE 

RAZORBACK SUCKER IN THE LOWER GRAND CANYON 

AND COLORADO RIVER INFLOW TO LAKE MEAD 

A SCIENCE PANEL REPORT

Final Report 

REPORT TO U.S. BUREAU OF RECLAMATION 

UPPER COLORADO REGION 

SALT LAKE CITY, UTAH 

REPORT OF INDEPENDENT SCIENCE PANEL 

Richard Valdez (chair), Chuck McAda, Gordon Mueller, 

Dale Ryden, and Melissa Trammell 

APRIL 1, 2012 

ii 
Preface April 1, 2012

PREFACE 

The U.S. Bureau of Reclamation (Reclamation) has undertaken an investigation to examine the 

potential of habitat for the federally endangered razorback sucker (Xyrauchen texanus) in the 

lower Grand Canyon. Reclamation, in collaboration with the U.S. Fish and Wildlife Service 

(USFWS), is investigating the potential for establishment of the razorback sucker in the lower 

Grand Canyon and may institute an augmentation program for the species in that area, if 

appropriate. This investigation addresses part of a conservation measure of the Final 

Environmental Impact Statement for the Colorado River Interim Guidelines for Lower Basin 

Shortages and Coordinated Operations for Lake Powell and Lake Mead. The measure is 

contained in Concurrences (Appendix A) of the 2007 Biological Opinion for that action which 

states that: "Reclamation will, as a conservation measure, undertake an effort to examine the 

potential of habitat in the lower Grand Canyon for the species [razorback sucker], and institute 

an augmentation program in collaboration with FWS, if appropriate."

Reclamation is coordinating this investigation with the U.S. Fish and Wildlife Service, Glen 

Canyon Dam Adaptive Management Program, Lower Colorado River Multi-Species 

Conservation Program, National Park Service, Grand Canyon Monitoring and Research Center, 

Nevada Department of Wildlife, Arizona Game and Fish Department, and the Hualapai Tribe. 

SWCA, Environmental Consultants was retained by Reclamation to assist with the assimilation 

of information for this investigation and to recommend an augmentation strategy for the 

razorback sucker. SWCA and Reclamation established three tasks: (1) assimilate, review, and 

summarize the habitat information for the species, (2) convene a Science Panel of species experts 

for recommended actions, and (3) develop a recommended augmentation strategy. 

This report is the second of three reports produced as part of this investigation that include:: 

1. Review and Summary of Razorback Sucker Habitat in the Colorado River System: This

report summarizes habitat used by the razorback sucker throughout its range in the 

Colorado River System, including conditions for spawning and egg incubation; larval 

drift corridors and distances; nurseries used by young; juvenile rearing areas; food 

requirements; movement; and subadult and adult habitat. The information contained in 

this report was used to better gauge the suitability of conditions for the species in the 

lower Grand Canyon and Colorado River inflow. 

2. The Potential of Habitat for the Razorback Sucker in the Lower Grand Canyon and 

Colorado River Inflow to Lake Mead: A Science Panel Report: This report contains the 

views, opinions, and recommendations of a panel of species experts on the suitability of

the lower Grand Canyon and Colorado River inflow for the razorback sucker. It was 

developed from a reconnaissance field trip and meetings of the Panel in September, 2010. 

3. Strategy for Establishing the Razorback Sucker in the Lower Grand Canyon and Lake 

Mead Inflow: This report describes a strategy for establishment of the razorback sucker in 

the lower Grand Canyon, either naturally through expansion of the Lake Mead population 

or possibly through augmentation. 

Science Panel Report Final Report 

iii 
Acknowledgments April 1, 2012 

ACKNOWLEDGMENTS 

The U.S. Bureau of Reclamation and SWCA Environmental Consultants appreciate the efforts of 

many individuals that provided support and input into this investigation and the development of 

the three reports (see names and affiliations below). Mark McKinstry, Reclamation’s Contract 

Officer Technical Representative, provided the impetus, support, and guidance for this project. 

We thank the members of the Science Panel (highlighted below) for their critical review, 

evaluation, and input necessary to the development of a scientifically defensible approach for 

evaluating the potential for introducing razorback suckers into the lower Grand Canyon. 

We thank the National Park Service for their collaboration and support of this project, especially 

Brian Healy, Emily Omana Smith, Nate Alvord, and Dave Loeffler of Grand Canyon National 

Park who provided logistical support and rafts for the reconnaissance field trip of September 16-

19, 2010, through the lower Grand Canyon. We thank Greg Squires of Lake Mead National 

Recreation Area for providing a boat to transport the Science Panel in the Lake Mead inflow. 

We thank the participants of the reconnaissance field trip for their valuable time and insight and 

the agencies for supporting members of their staffs to participate in this process. The Bar 10 

Ranch provided aerial and ground transportation from Flagstaff, Arizona to Whitmore Wash. 

Name Affiliation Role

Albrecht, Brandon Bio/West, Inc., Logan, UT Principal Investigator, Lake Mead Razorback 

Sucker Studies

Alvord, Nate National Park Service, Grand Canyon, AZ Staff Assistant, Grand Canyon National Park

Clark, Andy Arizona Game and Fish Department, Kingman, AZ Fisheries Program Manager, AGFD 

Hamill, John U.S. Geological Survey, Flagstaff, AZ Director, Grand Canyon Monitoring and 

Research Center 

Healy, Brian National Park Service, Flagstaff, AZ Fisheries Biologist, Grand Canyon National Park

Herndon, Debora Nevada Department of Wildlife NDOW Representative, Lower Colorado River 

Multi-Species Conservation Program 

House, Dorothy SWCA, Inc., Flagstaff, AZ SWCA Project Assistant 

Loeffler, Dave National Park Service, Grand Canyon, AZ Staff Assistant, Grand Canyon National Park

McAda, Chuck U.S. Fish and Wildlife Service (retired), Grand 

Junction, CO 

Science Panel 

McKinstry, Mark U.S. Bureau of Reclamation, Salt Lake City, UT Contract Officer Technical Representative 

Morgan, Annette The Hualapai Tribe, Peach Springs, AZ Tribal Representative 

Mueller, Gordon U.S. Geological Survey (retired), Denver, CO Science Panel 

Omana Smith, 

Emily 

National Park Service, Flagstaff, AZ Fisheries Biologist, Grand Canyon National Park

Ryden, Dale U.S. Fish and Wildlife Service, Grand Junction, CO Science Panel 

Sponholtz, Pam U.S. Fish and Wildlife Service, Flagstaff, AZ Project Coordinator and Fishery Biologist, 

Arizona Fishery Resources Office 

Stolberg, Jon U.S. Bureau of Reclamation, Boulder City, AZ BOR Representative, Lower Colorado River

Multi-Species Conservation Program 

Trammell, Melissa National Park Service, Salt Lake City Science Panel 

Valdez, Richard SWCA, Inc., Logan, UT Science Panel Chair 

Science Panel Report Final Report 

iv 
Table of Contents April 1, 2012 

TABLE OF CONTENTS

PREFACE......................................................................................................................................iii 

ACKNOWLEDGMENTS ............................................................................................................. iv 

1.0 INTRODUCTION ................................................................................................................. 1 

1.1 Role of the Science Panel ............................................................................................. 1 

1.2 Members of the Science Panel...................................................................................... 1 

1.3 Evaluation Process........................................................................................................ 2 

2.0 DISCUSSION AND CONCLUSIONS ................................................................................. 3 

2.1 Specific Questions Addressed by the Science Panel .................................................... 3 

2.2 Issues of Consideration................................................................................................. 8 

3.0 SUMMARY......................................................................................................................... 11 

LITERATURE CITED................................................................................................................. 13 

APPENDIX A: Science Panel Titles and Publications................................................................... 1 

Science Panel Report Final Report

v 
1.0 Introduction April 1, 2012 

1.0 INTRODUCTION 

1.1 Role of the Science Panel 

The U.S. Bureau of Reclamation (Reclamation), as part of a 2007 Biological Opinion (USFWS

2007), has undertaken an effort to examine the potential of habitat for the federally endangered 

razorback sucker (Xyrauchen texanus) in the lower Grand Canyon. Reclamation, in collaboration 

with the U.S. Fish and Wildlife Service (USFWS), may institute an augmentation program for 

the species, if appropriate. This report presents the results of an evaluation by an independent 

scientific review panel (Science Panel) and summarizes their recommendations on three key 

questions: 

1. Is the habitat of the lower Grand Canyon and Lake Mead inflow suitable for the 

razorback sucker? 

2. Should Reclamation and the USFWS proceed with efforts to introduce razorback suckers 

into the lower Grand Canyon?

3. If appropriate, what methods or strategies should be considered in introducing razorback 

suckers into the lower Grand Canyon?

1.2 Members of the Science Panel 

A list of prospective panelists was compiled by SWCA, a contractor to Reclamation for this 

project. Reclamation and SWCA selected panelists based on their availability and expertise of

the subject matter. It was desirable to have a cross-section of species experts with experience and

expertise in the lower and upper basins of the Colorado River System. The primary evaluation 

factors for choice of panelists were: 

• Past or ongoing experience in the Colorado River System with the razorback sucker; 

• A history of research, involvement, and knowledge of water and biological issues in the 

Colorado River System; and 

• The ability to provide an objective and unbiased view of current policies and decisions 

that affect the razorback sucker in the Colorado River System. 

Members of the Science Panel were as follows (see Appendix A for titles and publications): 

• Chuck McAda: U.S. Fish and Wildlife Service (retired). 

• Gordon Mueller: U.S. Geological Survey (retired). 

• Dale Ryden: U.S. Fish and Wildlife Service. 

• Melissa Trammell: National Park Service. 

• Richard Valdez (chair): SWCA, Environmental Consultants. 

Science Panel Report Final Report

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1.0 Introduction April 1, 2012 

1.3 Evaluation Process 

Members of the Science Panel were requested to address the three key questions identified in 

section 1.1 above. The following steps were taken to assist the Panel with an evaluation of the 

available scientific information and to facilitate addressing the questions and the formulation of 

recommendations: 

• Review of Habitat Information: The panelists were each provided with a Draft Report 

of a “Review and Summary of Razorback Sucker Habitat in the Colorado River System” 

(Valdez et al. 2012a) This report summarized habitat used by the razorback sucker 

throughout its range in the Colorado River System, including conditions for spawning 

and egg incubation; larval drift corridors and distances; nurseries used by young; juvenile 

rearing areas; food requirements; movement; and subadult and adult habitat. The 

information contained in this report was provided to the Science Panel to help them better 

gauge the suitability of conditions for the species in the lower Grand Canyon and Lake 

Mead inflow. The panelists were familiar with most of the information provided and the 

report provided a synthesis of that information. 

• Reconnaissance Field Trip: A field trip was organized and conducted by Reclamation 

and SWCA, in cooperation with the National Park Service, on September 16-19, 2010, 

from Whitmore Wash (RM 187) downstream to Pearce Ferry (RM 280). The purpose of 

the trip was to familiarize the Panel with this reach of the Colorado River and to provide 

a setting conducive to a focused evaluation of the information and the conditions of the 

lower Grand Canyon. The trip was also used as an opportunity to conduct a series of 

closed and open meetings of the Science Panel to address the key and specific questions 

(see sections 1.1 and 2.1). In addition to the Science Panel, 13 individuals from

cooperating State and Federal agencies, a Native American Tribe, and private contractors 

were invited to participate in the trip to provide agency insight and their views on the 

potential for introducing razorback suckers into the lower Grand Canyon (see Preface and 

Acknowledgments). 

• Meetings of Science Panel: The Science Panel was formally convened three times 

during and immediately after the reconnaissance field trip. Each of the meetings was 

restricted to the panelists and no observers or onlookers were allowed. In addition to 

these closed meetings, two meetings were held in which trip participants provided their 

opinions and exchange of views with the Science Panel. Notes on each meeting were 

recorded by SWCA. 

• Concurrence of Reports and Recommendations: Following the completion of three 

reports on habitat of the razorback sucker (Report #1), evaluation and recommendations 

of the Science Panel (Report #2), and recommended establishment strategy (Report #3), a 

conference call was held with the members of the Science Panel to obtain concurrence on 

the scientific validity of the reports and on the accuracy of their conclusions and 

recommendations. No written dissenting opinions or views were issued by the panelists 

for the contents of this report or for the conclusions and recommendations.

Science Panel Report Final Report

2 
2.0 Discussion and Conclusions April 1, 2012

2.0 DISCUSSION AND CONCLUSIONS 

The Science Panel was presented with six specific questions to help direct their evaluation and 

recommendations with respect to the three key questions. The following is an overview of the 

discussions and conclusions reached by the Panel with respect to each of the specific questions. 

The discussions were captured and assimilated by the Science Panel chair, and responses by 

individual panelists are not provided because of the lengthy dialogue and discourse that ensued 

with each question. Notes on each meeting of the Science Panel were recorded by SWCA, but 

are not made available with this report because of their length and conversational nature. 

2.1 Specific Questions Addressed by the Science Panel 

The following specific questions were asked to be addressed by the Science Panel. The responses 

below were written by the Science Panel chair based on the recorded discussions that took place 

in the Science Panel meetings. 

1. What do you believe are the potential habitat attributes of western Grand Canyon and 

the Lake Mead inflow for the razorback sucker? 

• Basis of Information: Of the five members of the Science Panel, three had previously 

visited or sampled fish in the lower Grand Canyon. One panelist had participated in a 

habitat reconnaissance of the lower Grand Canyon the year before the trip, and a second 

panelist had directed fishery investigations in this reach of the Colorado River in 1992 to 

1995. The third panelist familiar with this reach of the Colorado River had visited the 

area in the 1980s. The panel members appreciated the information provided to them in 

Report #1, but requested additional and more specific information on the fish community 

and food base of the lower Grand Canyon. No food base information was available, but 

recent work in the Grand Canyon further upstream was included in a subsequent draft of 

the report. 

• Visual Assessment of Habitat: Members of the panel acknowledged that physical 

habitat in the lower Grand Canyon appeared to be within the range of habitats used by 

razorback suckers or in which they had observed the species in other parts of the basin. 

Although large floodplains are absent from lower Grand Canyon, panelists felt that small 

backwaters and a complex shoreline could provide nursery habitat for young suckers. 

However, the scientists expressed concern over the ephemeral nature of these habitats—

including backwaters—caused by daily, monthly, and seasonal operations of Glen 

Canyon Dam. Panelists identified suitable habitats as shorelines with cobble and rock 

outcrops, inundated or over-hanging riparian vegetation, in-channel woody debris, 

alluvial cobble/gravel bars, and ephemeral backwaters. It was noted that backwaters 

regularly inundated and desiccated by dam operations are unstable and cause young fish 

to move periodically, exposing them to predation and possibly contributing to starvation. 

Seine hauls taken in backwaters during the reconnaissance field trip yielded numerous 

young flannelmouth suckers and bluehead suckers (native suckers commonly found with 

razorback suckers), indicating that the other native suckers are successfully using the 

lower Grand Canyon for at least rearing. The most apparent missing component of habitat 

Science Panel Report Final Report

3 
2.0 Discussion and Conclusions April 1, 2012

was the large floodplains complexes used by young razorback suckers as nurseries and 

rearing areas in some reaches of the Green and Upper Colorado rivers where the species 

persists, and in the Lower Colorado River Basin where the species was historically 

abundant. Some panelist contrasted and compared the habitat of the lower Grand Canyon 

with reaches elsewhere in the Colorado River System where there are few or no 

razorback suckers, such as the Colorado River between the Dolores River and Moab (i.e., 

“Daily Reach”), in Canyonlands National Park, or the lower end of the San Juan River 

(i.e., RM 68 downstream). The panelists requested more information on ecological 

attributes of the area (e.g., fish community, food base) to better assess habitat potential. 

• Conclusion: The habitat of the lower Grand Canyon is not strikingly like those regions of 

the Colorado River System where the razorback sucker is abundant—or was historically 

abundant. This reach of the Colorado River could probably support small numbers of 

adult and subadult razorback suckers. There are some large cobble/gravel bars that could 

be used for spawning and there is a limited amount of nursery habitat that may be largely 

ephemeral, depending on dam operations. The area lacks the channel complexity, side 

channels, and oxbows that form large protected and productive habitats in which the 

species thrives in other parts of the basin. It also lacks the large floodplain habitats and 

complexes used by the young for nursing and rearing. There are low-lying tributary 

mouths that could serve as inundated floodplains (e.g., Burnt Spring Canyon, Clay Tank 

Canyon [Lost Creek]), but these are disconnected from the river by large sand/silt berms. 

The inaccessibility and remoteness of this region precludes the use of heavy equipment to 

mechanically remove these berms. Furthermore, the river flow in this reach is affected by 

releases from Glen Canyon Dam that vary seasonally and may inundate or isolate these 

floodplains in an unpredictable and unreliable manner. 

2. Do you believe the region of the lower Grand Canyon and the Lake Mead inflow is 

currently suitable habitat for razorback sucker? 

• Species is Highly Adaptable: One panelist was quick to point out that biologists and 

managers alike should not be too quick to pre-determine what river regions are suitable 

for the razorback sucker. In many places in the Colorado River System, the species has 

demonstrated high adaptability and use of a wide range of habitats. The razorback sucker 

is the only large-bodied fish species in the Colorado River System (except possibly for 

the bonytail) that spawns and recruits in riverine as well as reservoir and pond habitats. 

• Historic Habitat Distribution: The historic distribution of the razorback sucker supports 

the hypothesis that there are large numbers of razorback suckers downstream of Grand 

Canyon because of habitat complexity, but the species is largely absent from the canyon 

because of the lack of that complexity. One panel member noted that this species 

historically was consistently found primarily in river reaches with large floodplains that 

became inundated with spring runoff and often held water year-around. Historic records 

indicate that the species probably used canyon-bound reaches transiently, possibly for 

spawning, feeding, and as passage between alluvial reaches and floodplains. Other 

panelists pointed out that the species is currently found in reaches of the Colorado River 

system absent of large floodplains, such as the San Juan River; or in locations in which it 

uses gravel pits as surrogates for floodplains, such as in the upper Colorado River near 

Grand Junction. 

Science Panel Report Final Report

4 
2.0 Discussion and Conclusions April 1, 2012

• Lower Grand Canyon and Lake Mead Inflow Habitat Continuum: Panel members 

felt that the most likely scenario for the razorback sucker to become established in the 

lower Grand Canyon is as an extension of the Lake Mead population. The river in the 

lower Grand Canyon apparently provides habitat for spawning, juveniles, and adults, but 

the nursery habitat is limited to ephemeral backwaters; the most suitable nursery and 

rearing habitat is downstream in the Lake Mead inflow, where larvae of presumably the 

Lake Mead population have been found. 

• Conclusion: The physical habitat of the lower Grand Canyon appears to be marginally 

suitable for the razorback sucker with a variety of habitats that could be used by adults, 

subadults, juveniles, and possibly for spawning and rearing. However, the absence of 

large floodplains reduces the likelihood for a self-sustaining population reliant only on 

the lower Grand Canyon, and a connection with the Lake Mead inflow would be 

necessary to support all life stages. Possibly fish could spawn in the lower canyon and 

their young can drift to nursery habitat in the Lake Mead inflow. 

3. What do you believe are the three most important actions that would need to be taken 

to establish the razorback sucker in the lower Grand Canyon and the Lake Mead

inflow? 

• Assimilate Additional Information: The reach of the Colorado River through the lower 

Grand Canyon (i.e., Diamond Creek to Pearce Ferry) has not been surveyed for fish as 

intensively as the river further upstream. Intensive investigations of the hydrology, 

sediment, food base, riparian vegetation, and fish community have been conducted in the 

river between Glen Canyon Dam and Diamond Creek (e.g., Gloss et al. 2005; Melis 

2011), but relatively few studies have extended downstream. Panel members requested 

additional information on the contemporary fish community, habitat, and food base. The 

available information was provided from past investigations and studies of the Colorado 

River upstream of the lower Grand Canyon in Report #1 on habitat, but the ecological 

information on this reach of river is limited. 

• Initiate Fish Community Surveys: The Science Panel felt that a fish community survey 

from Diamond Creek to Pearce Ferry is warranted to: (a) determine if razorback suckers 

are present in the area, (b) determine if fish from the Lake Mead population are using the 

lower Grand Canyon, (c) better understand from the present fish community if ecological 

conditions might be suitable for certain life stages of the razorback sucker. 

• Release Small Numbers of Sonic-Tagged Fish. Small numbers of large sonic-tagged 

fish should be released at the beginning of fish community surveys to: (a) provide fish 

during the fish community survey for crews to track and better understand where to 

sample for razorback suckers, (b) determine if stocked fish will remain in the area, (c)

determine habitat use, and (d) to help locate other razorback suckers in the area (i.e., 

Judas fish). 

• Conclusion. Before proceeding with any efforts to introduce razorback suckers into the 

lower Grand Canyon, it should first be determined if the species is already present in the 

area and if the existing fish community shows that the area can support the species 

ecologically. Flannelmouth suckers are now common in the lower canyon and this 

species has similar ecological requirements, except possibly for large floodplains used as 

Science Panel Report Final Report

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2.0 Discussion and Conclusions April 1, 2012

nurseries by young razorback suckers. Fish community surveys should be conducted in 

the lower Grand Canyon, and small numbers of sonic-tagged fish should be released for 

tracking these fish simultaneous to the surveys. 

4. If augmentation is appropriate, what do you believe would be the most effective fish 

introduction strategy?

• Use Wild Conditioned Fish. Members of the Science Panel urged the use of small 

numbers of wild fish of sufficient size, experience, and conditioning to avoid predation. 

These fish may be wild-caught larvae raised in protected, predator-free ponds to a 

sufficient size (e.g., ≥ 350 mm TL), or they may be large wild fish translocated from a 

wild population. 

• Use Fish From Near-by Populations. Panelists strongly recommended the use of fish 

from either the Lake Mead population of razorback suckers or from the Colorado River 

below Davis Dam, near Laughlin, Nevada. They felt that these fish were genetically 

diverse and similar to the Lake Mead fish, with behavioral traits that would enhance their 

chances of survival in the lower Grand Canyon. 

• Release Adults Just Prior to Spawning. Lake Mead biologists are using the strategy of 

releasing wild sonic-tagged adults into areas with suitable spawning habitat just prior to 

spawning. Tracking these fish and sampling the occupied areas show that these adults 

will congregate with other wild spawning adults and possibly engage in spawning. Adults 

near spawning condition released in deep pools near large alluvial cobble/gravel bars 

could produce young that would imprint to the site. 

• Release Fish as High Upstream as Possible. Panelists believe that fish should be 

released as high upstream as possible in the lower Grand Canyon, upstream of Diamond 

Creek and preferably below Lava Falls rapid. This gives a greater chance for fish to 

remain in the lower Grand Canyon. Alternatively, fish released near Diamond Creek, 

Spencer Canyon, and Salt Creek would be near potential spawning bars and sufficiently 

high in the system to minimize escapement from the area. 

• Acclimate the Fish Before Release. Panel members shared their experiences with 

releasing a variety of fish species into the wild, including razorback suckers, and 

expressed concern over the long-distance movements seen immediately after release. 

This “fright response” can be reduced by holding fish in live pens in the river prior to 

release; this allows the fish to acclimate and reduces their movement when released from

the pens. 

• Conclusion. The Science Panel felt that the best strategy is to release small numbers of 

wild-born adults that are river-conditioned and acclimated. The Panel also felt that fish 

should be released as far upstream as possible in the lower Grand Canyon (i.e., below 

Lava Falls rapid), or possibly at potential spawning sites at Diamond Creek, Spencer 

Canyon, and Salt Creek. 

Science Panel Report Final Report

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2.0 Discussion and Conclusions April 1, 2012

5. What can be done to link razorback suckers in the lower Grand Canyon and the Lake 

Mead inflow with the population currently in Lake Mead?

• Determine if Lake Mead Fish are Already Using Lower Grand Canyon. A 

comprehensive fish survey is needed of the lower Grand Canyon (Lava Falls rapid to 

Lake Mead inflow area) to determine if razorback suckers are already present in the area. 

Many fish from the Lake Mead population are PIT-tagged and some are sonic-tagged, 

and these fish would be easy to identify if found in the lower canyon. 

• Translocate Lake Mead Fish. If introduction is deemed appropriate, the translocation of 

Lake Mead fish could provide the most direct linkage between the lower Grand Canyon 

and Lake Mead inflow. This may be done by translocating small numbers of wild adults; 

or fish that have been raised from wild-spawned larvae in riverside grow-out ponds. The 

fish should be raised in an environment that conditions them to velocity, cover, predators, 

and natural foods to maximize their survival. 

• Promote Expansion of Lake Mead Population. Ongoing research on the Lake Mead 

population continues to provide a better understanding of the strategies of larvae and 

young razorback suckers in surviving the large numbers of predators in Lake Mead. High 

turbidity associated with inflows and shoreline vegetation and cobble appears to provide 

cover from predators for the young fish. These conditions exist in the Colorado River 

inflow to Lake Mead, and may be conducive to establishing a population that makes full 

use of available habitats in the lower Grand Canyon, as well as the Lake Mead inflow. 

• Conclusion. Panel members reiterated that habitat in the lower Grand Canyon alone was 

marginal for the razorback sucker, primarily because of the absence of floodplains for 

nursing and rearing and the presence of only small numbers of ephemeral backwaters. 

The razorback sucker would most likely become established in the lower Grand Canyon 

as an extension of the Lake Mead population. 

6. What are the most important issues that would need to be addressed or considered in 

establishing razorback suckers in the lower Grand Canyon and the Lake Mead inflow? 

• Do No Harm to Lake Mead Population: The introduction of razorback suckers into the 

lower Grand Canyon should in no way compromise the demographic or genetic integrity 

of the Lake Mead population. Members of the Science Panel were adamant that any 

effort to introduce razorback suckers into the lower Grand Canyon should in no way 

compromise the Lake Mead population. They expressed concern over the introduction of 

particularly large numbers of razorback suckers from outside sources with unknown or 

limited genetic diversity, and recommended against the use of hatchery-reared fish from

captive broodstock. These fish, if they survive in sufficient numbers, could potentially

swamp the genetic uniqueness of the Lake Mead fish and negatively affect the inherited 

behavior and adaptive mechanisms that would lessen the chances of survival for the 

progeny. A preferred source of fish for stocking was identified as fish from the Lake 

Mead population or from the Colorado River below Davis Dam, although the numbers 

are small. Possibly wild larvae could be raised in protective ponds to a sufficient size and 

translocated into the lower Grand Canyon. 

Science Panel Report Final Report

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2.0 Discussion and Conclusions April 1, 2012

• Establish Measures of Success. Augmentation should be linked to the expectation of a 

defined measure of success. Success in establishing the species in the lower Grand 

Canyon should be measured as use of the area by subadults and adults for feeding and 

spawning and a linkage to the Lake Mead population. In all likelihood, establishment of 

the razorback sucker in the lower Grand Canyon will occur as an extension of the Lake 

Mead population. The numbers of adults and subadults that use the lower Grand Canyon 

may be low; possibly 100-200 fish; e.g., the 30 mi section of complex habitat might be 

expected to support fewer than 10 fish/mile. 

• Conclusion. Care should be taken to ensure that any action to establish the razorback 

sucker in the lower Grand Canyon does not compromise the Lake Mead population. 

Establishing the species in the area may mean promoting an expansion of the existing 

Lake Mead population and success may be measured as use by the species as an 

extension of the Lake Mead population. 

2.2 Issues of Consideration 

As the Science Panel addressed the key and specific questions, several issues of consideration 

were identified. Individual panel members felt that these issues needed to be addressed—or at 

least discussed—as the key and specific questions were being addressed. The issues are the 

following: 

1. Is the goal of introducing fish into the lower Grand Canyon a biological question or 

a political issue? 

One panelist felt that the task given to the Science Panel presumed that razorback suckers would 

be introduced into an area that may not be entirely suitable to the species. Some panel members 

did not believe that it was a foregone conclusion that razorback suckers would inevitably be 

introduced into the lower Grand Canyon, particularly as political expediency to satisfy the 

conditions of a biological opinion. Members of the Panel agreed that the decision to introduce 

razorback suckers into the lower Grand Canyon should be based on the biological information, a 

rational evaluation of the likelihood of success, and on the contribution of the effort to the 

conservation of the species—and not simply on the need to satisfy the biological opinion. 

2. If the decision is made to introduce razorback suckers into the lower Grand 

Canyon, a strategy should be employed that will maximize survival of the 

introduced fish. 

Several panelists pointed out that traditional methods of hatchery culture and releases of large 

numbers of larval and juvenile razorback suckers into the wild have had little success. Survival 

of these fish has traditionally been low for a number of largely unknown reasons, but certainly 

predation by nonnative fishes is a principal factor. A strategy should be employed that uses the 

techniques that result in the highest possible survival rate for the fish and subsequent use of the 

area. One panelist strongly advocated the use of “conditioned fish” as part of a translocation 

strategy in which large razorback suckers are taken from an existing wild population, such as the 

Laughlin area below Davis Dam, or from the Lake Mead population. Using such fish would 

increase the chances of survival because individuals would be adapted to a riverine environment 

Science Panel Report Final Report

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2.0 Discussion and Conclusions April 1, 2012

and adept at finding habitat and food, as well as avoiding predators. The process for reaching a 

decision to augment the razorback sucker in the lower Grand Canyon is described in a strategy to 

establish the species developed as part of this deliberative process (Valdez et al. 2012b). 

3. Introduction of razorback suckers could also introduce aquatic invasive species into 

the lower Grand Canyon and Lake Mead inflow. 

Water used to transport fish from other systems could be carrying pathogens, diseases, or aquatic 

invasive species, such as crustaceans, mollusks, or fish that could negatively affect the ecosystem

of the lower Grand Canyon and Lake Mead inflow. Quagga mussels are already abundant in 

Lake Mead below the inflow, and New Zealand mudsnails are common in the Lees Ferry reach 

below Glen Canyon Dam. However, other invasive species can be introduced, and the Science 

Panel urged care in transporting fish into the area. Panel members also pointed out that the 

interstate transport of fish requires State board inspections that may require sacrificing a 

sufficient number of fish for testing (e.g., 50). Such inspections may be required if fish are taken 

from Laughlin (Nevada) and transported for release at Diamond Creek (Arizona). Because of the 

small numbers of wild fish available, it may be necessary to develop alternative means for 

satisfying State board inspection requirements. 

4. Nonnative fish predators are abundant in the Lake Mead inflow and will likely limit 

survival of young razorback suckers. 

Nonnative fish predators are known to suppress the survival of young razorback suckers. Some

members of the Science Panel strongly believe that young razorback suckers must be reared in 

predator-free environments to ensure adequate survival; however, any form of nonnative fish 

control or removal in the lower Grand Canyon and Lake Mead inflow is impractical. Panel 

members strongly recommend the use of large fish for initial releases, though the young fish 

would still be subject to substantial predation risk. Recent investigations of the Lake Mead 

population show that survival and recruitment of young naturally-spawned razorback suckers is 

made possible by the turbidity of the inflow and the presence of shoreline vegetation and cobble 

that provide cover from predators. 

5. Razorback suckers may already be present in the lower Grand Canyon or 

individuals from the Lake Mead population may be using the area intermittently. 

The lower Grand Canyon from Diamond Creek to Pearce Ferry was sampled intensively for fish 

during 1992–1995 and 2004-2006. Periodic sampling efforts were made by the Arizona Game

and Fish Department (AGFD) and the Grand Canyon Monitoring and Research Center 

(GCMRC) in 2007–2008 as a pilot study to investigate channel catfish capture methods and to 

identify the extent of invasion by channel catfish into the Grand Canyon. Razorback suckers 

have not been caught or sighted during any of these sampling efforts. However, there have been 

dramatic habitat changes in this reach of the Colorado River since the level of Lake Mead began 

lowering in the year 2000 and much of the inflow delta is exposed. Members of the Science 

Panel each have experience in sampling razorback suckers and recognize the elusiveness of the 

species, and the possibility that small numbers of individuals are present in the lower Grand 

Canyon. Panel members agreed that a first step in this evaluation process should be a more 

thorough fish community sampling effort. 

Science Panel Report Final Report

9 
2.0 Discussion and Conclusions April 1, 2012

6. Lower Grand Canyon and Lake Mead inflow will likely continue to change 

physically, chemically, and biologically with dam releases and changing lake levels. 

The habitat in the lower Grand Canyon and Lake Mead inflow (primarily from about Spencer 

Canyon [RM 246] to below Pearce Ferry [RM 280] is in a transitional stage as the Colorado 

River continues to carve a channel into the newly exposed deltaic deposits. This dynamic habitat 

condition is likely to continue for a number of years, depending on Lake Mead water levels, the 

stability of the newly formed river channel, and the ongoing effect of climate change on the 

hydrology of the Colorado River System. The effect of this dynamic nature inflow on the 

razorback sucker is unknown, but although the habitat appears unstable, the erosion of enriched 

deltaic deposits could contribute substantially to the food base and the instability may favor 

native species over less adaptable nonnative fishes. As evidence of the dynamic nature of the 

inflow channel, a severe rapid that formed about 1 mi downstream of Pearce Ferry in 2010 

impeded the movement of sonic-tagged razorback suckers in 2010, but by 2011 the channel had 

continued to change, allowing the upstream movement of fish. 

7. Maintain ongoing coordination with stakeholders and interested parties. 

Any plans to introduce razorback suckers into the lower Grand Canyon should continue to be 

coordinated by Reclamation with stakeholders and interested parties. Reclamation has committed 

to undertake this investigation in collaboration with the U.S. Fish and Wildlife Service and in 

coordination with Glen Canyon Dam Adaptive Management Program, Lower Colorado River 

Multi-Species Conservation Program, National Park Service, Grand Canyon Monitoring and 

Research Center, Nevada Department of Wildlife, Arizona Game and Fish Department, and the 

Hualapai Tribe. Coordination should also be maintained with the Lake Mead Razorback Sucker 

Work Group and Bio/West, the contractor conducting investigations of the razorback sucker in 

Lake Mead.

Science Panel Report Final Report

10 
3.0 Summary April 1, 2012

3.0 SUMMARY 

The following is a summary of the Science Panel for the potential of habitat for the razorback 

sucker in the lower Grand Canyon and Colorado River inflow to Lake Mead: 

1. Support efforts to better understand and promote the razorback sucker population 

in Lake Mead. 

The razorback sucker population in Lake Mead is the largest reproducing and recruiting 

population in the Colorado River System. Efforts to conserve and expand this population should 

be promoted, and any actions to establish the species in the lower Grand Canyon should be done 

in a manner that complements those efforts and does not harm or compromise the Lake Mead 

population. The Science Panel views the lower Grand Canyon and Lake Mead inflow as a single 

contiguous ecological complex, and the most likely way in which razorback suckers could 

become established in the lower Grand Canyon is as an expansion of the Lake Mead population. 

2. Identify and assimilate the existing and historic information on the fish community, 

food base, and habitat of the lower Grand Canyon and Lake Mead inflow. 

Much of the literature and information on the lower Grand Canyon was assimilated in Report #1 

on habitat of the razorback sucker. Information on the species and from the area should be kept 

current and ongoing involvement and participation should be maintained with the Lake Mead 

Razorback Sucker Work Group. The fish community of the lower Grand Canyon should be 

surveyed and habitat should be determined from sonic-tagged razorback suckers. An expansive 

habitat assessment (e.g., PHABSIM) is not recommended, nor is an expansive food base study. 

The food base should be quantified as the macroinvertebrate densities and diversity in primary 

habitats, including cobbles, deposits, talus, and woody debris. 

3. Initiate fish community surveys of the Lower Grand Canyon (Lava Falls rapid to 

Lake Mead inflow) and determine if razorback suckers are present. 

Fish surveys should be conducted from Lava Falls rapid to the Lake Mead inflow to document 

the fish community in this reach of the Colorado River. Intensive fish surveys have not been 

conducted in this area since 1995, and large changes to the Lake Mead inflow from a declining 

reservoir elevation have changed the habitat and likely the fish community. A larval fish survey 

could/should serve as the initial sampling effort to identify all spawning fish in the system, 

including razorback suckers that may have gone undetected. The inflow has not stabilized 

because the river continues to carve a channel in the deltaic deposits and fish habitat and 

populations may continue to change. As these surveys are being conducted small numbers of 

large sonic-tagged razorback suckers should be released to determine: (a) if the fish will remain 

in the area, (b) their movement and habitat use, and (c) to help locate other razorback suckers in 

the area (as Judas fish). Wild fish should be used, such as large individuals from the population 

below Davis Dam or from Lake Mead. About 10–15 fish should be released as far upstream as 

possible in the lower Grand Canyon, or in pools adjacent to large cobble/gravel bars at Diamond 

Creek, Spencer Canyon, and Salt Creek. Field crews conducting fish surveys can simultaneously 

sample fish and monitor the sonic-tagged fish. Sampling should before and after spawning 

(February-May) and larvae should be sampled thereafter. 

Science Panel Report Final Report

11 
3.0 Summary April 1, 2012

4. Evaluate lower Grand Canyon/Lake Mead inflow in a basin-wide perspective of 

razorback sucker conservation. 

The Razorback Sucker Recovery Goals call for two self-sustained populations each in the lower 

and upper Colorado River basins. These recovery goals do not specify where these populations 

should be established. Biologists and managers should identify and describe areas that provide 

the greatest potential for conservation of the species. The Lake Mead population has been 

recognized as the largest self-sustaining population and an expansion of the population is 

desirable. The lower Grand Canyon may have a role in that expansion, but biologists and 

managers should proceed cautiously so as not to compromise the Lake Mead population in 

attempting to establish razorback suckers in lower Grand Canyon. A long-term definition of 

success may simply be establishing the presence of fish in the lower Grand Canyon as an 

extension of the Lake Mead population. 

5. If augmentation is deemed appropriate, use translocated wild fish. 

Augmentation of the razorback sucker into the lower Grand Canyon should proceed with caution 

so as not to swamp the genetic diversity of the wild Lake Mead population. The need for 

augmentation should be determined following fish community surveys of the lower Grand 

Canyon and Lake Mead inflow. Augmentation, if deemed appropriate, should involve small 

numbers of large fish from near-by populations. Large fish may be taken from the Lake Mead 

population or from the lower Colorado River below Davis Dam. Alternatively, wild larvae may 

be captured and raised in grow-out ponds such as isolated lakeside coves. This will help to 

condition the fish to natural foods and habitat. The fish should be stocked at a sufficient size to 

minimize predation and enhance survival (≥ 350 mm TL), based on findings in the lower and 

upper basins. Large numbers of small hatchery-reared fish should not be used. 

Science Panel Report Final Report

12 
Literature Cited April 1, 2012 

LITERATURE CITED 

Gloss, S.P., J.E. Lovich, and T.S. Melis, eds. 2005. The state of the Colorado River ecosystem in 

Grand Canyon: U.S. Geological Survey Circular 1282, 220 p. (Also available at 

http://pubs.usgs.gov/circ/1282/.) 

Melis, T.S., ed. 2011. Effects of three high-flow experiments on the Colorado River ecosystem

downstream from Glen Canyon Dam, Arizona: U.S. Geological Survey Circular 1366, 

147 p. 

USFWS (U.S. Fish and Wildlife Service). 2007. Final biological opinion for the proposed 

adoption of Colorado River interim guidelines for lower basin shortages and coordinated 

operations for Lake Powell and Lake Mead. December 12, 2007. U.S. Fish and Wildlife 

Service, Phoenix, AZ. 

Valdez, R.A., D.A. House, M.A. McLeod, and S.W. Carothers. 2012a. Review and summary of 

razorback sucker habitat in the Colorado River System, Report Number 1. Final Report 

prepared by SWCA, Environmental Consultants for U.S. Bureau of Reclamation, Upper 

Colorado Region, Salt Lake City, UT. 

Valdez, R.A., D.A. House, M.A. McLeod, and S.W. Carothers. 2012b. Strategy for establishing 

the razorback sucker in the lower Grand Canyon and Lake Mead inflow, Report Number 

3. Final prepared by SWCA, Environmental Consultants for U.S. Bureau of Reclamation, 

Upper Colorado Region, Salt Lake City, UT.

Science Panel Report Final Report

13 
Appendix A: Science Panel Titles and Publications April 1, 2012 

APPENDIX A: Science Panel Titles and 

Publications 

Chuck McAda 

Present Position: Project Leader, Colorado River Fishery Project; U.S. Fish and Wildlife 

Service, Grand Junction, CO (retired) 

Relevant Reports and Publications: 

McAda, C.W., J.W. Williams, J.S. Cranney, T.E. Chart, W.R. Elmblad, and T.P. Nesler. 1994. 

Interagency standardized monitoring program: summary of results, 1986–1992. U.S. Fish 

and Wildlife Service, Grand Junction, CO. 

McAda, C.W., and R.S. Wydoski. 1980. The razorback sucker, Xyrauchen texanus, in the Upper 

Colorado River Basin, 1974-76. Technical Papers of the U.S. Fish and Wildlife Service 

99. U.S. Fish and Wildlife Service, Washington, D.C. 

McAda, C.W. 2003. Flow recommendations to benefit endangered fishes in the Colorado and 

Gunnison rivers. Upper Colorado River Endangered Fish Recovery Program, Denver, 

CO. 

Burdick, B.D., R S. Wydoski and C.W. McAda. 1995. Stocking plan for razorback sucker in the 

upper Colorado and Gunnison rivers. Final Report to the Recovery Implementation 

Program for the Endangered Fishes of the Upper Colorado River Basin. U.S. Fish and 

Wildlife Service, Denver, CO. 

Nesler, T.P., K. Christopherson, J.M. Hudson, C.W. McAda, F. Pfeifer, and T.E. Czapla. 2003. 

An integrated stocking plan for razorback sucker, bonytail, and Colorado pikeminnow for 

the Upper Colorado River Endangered Fish Recovery Program. Final Report of Upper 

Colorado River Endangered Fish Recovery Program, Denver, CO. 

Francis, T.A., and C.W. McAda. 2006. Overview of the Upper Colorado River Recovery 

Program propagation program with a preliminary assessment of survival of stocked fish 

in the rivers of the Upper Colorado River Basin. Draft report to Upper Colorado River 

Recovery Program, U.S. Fish and Wildlife Service, Grand Junction, CO. 

Science Panel Report Final Report

A-1 
Appendix A: Science Panel Titles and Publications April 1, 2012 

Gordon A. Mueller 

Present Position: U.S. Geological Survey, Denver, CO (retired). 

Relevant Reports and Publications: 

Mueller, G., and D.K. Foster. 1999. A case for site acclimation in the reintroduction of the 

endangered razorback sucker (Xyrauchen texanus). U.S. Geological Survey Open-File 

Report 99-110, MESC, Denver Field Office, CO. 

Mueller, G., P.C. Marsh, G. Knowles, and T. Wolters. 2000. Distribution, movements, and 

habitat use of razorback sucker (Xyrauchen texanus) in a lower Colorado River reservoir, 

Arizona-Nevada. Western North American Naturalist 60:180–187. 

Mueller, G., and T. Burke. 2005. Survival of young razorback suckers in relation to stocking 

rates and in the presence or absence of predator communities in Lake Mohave, ArizonaNevada. Proceedings of Restoring Native Fish to the Lower Colorado River, held in Las 

Vegas, Nevada, July 13–14, 1999. 

Mueller, G.A., and P.C. Marsh. 2002. Lost, a desert river and its native fishes: A historical 

perspective of the Lower Colorado River, Information and Technology Report 

USGS/BRD/ITR—2002—0010: U.S. Government Printing Office, Denver, CO. 

Mueller, G.A., P.C. Marsh, D. Foster, M. Ulibarri and T. Burke. 2003. Factors influencing poststocking dispersal of razorback sucker. North American Journal of Fisheries Management 

23(1): 270–275. 

Mueller, G.A. 2006. Ecology of bonytail and razorback sucker and the role of off-channel 

habitats in their recovery. U.S. Geological Survey Investigations Report 2006-5-65. 

Science Panel Report Final Report

A-2 
Appendix A: Science Panel Titles and Publications April 1, 2012 

Dale W. Ryden: 

Present Position: Project Leader, Colorado River Fishery Project; U.S. Fish and Wildlife 

Service, Grand Junction, CO. 

Relevant Reports and Publications: 

Ryden, D.W. 1997. Five-year augmentation plan for razorback sucker in the San Juan River. 

U.S. Fish and Wildlife Service, Grand Junction, CO. 

Ryden, D.W. 2000. Monitoring of experimentally stocked razorback sucker in the San Juan 

River: March 1994 through October 1997. San Juan River Basin Recovery 

Implementation Program, USFWS, Albuquerque, NM. 

Ryden, D.W. 2001. Monitoring of razorback sucker stocked into the San Juan River as part of a 

five-year augmentation effort: 2000 Interim progress report (final). U.S. Fish and 

Wildlife Service, Colorado River Fishery Project, Grand Junction, CO. 

Ryden, D.W. 2009. Long term monitoring of sub-adult and adult large-bodied fishes in the San 

Juan River: 2008. Interim Progress Report (Final Report). U. S. Fish and Wildlife 

Service, Colorado River Fishery Project. Grand Junction, CO. 

Propst, D.L., S.P. Platania, D.W. Ryden, and R.L. Bliesner. 2000. San Juan River monitoring 

plan and protocols. San Juan River Basin Recovery Implementation Program, U.S. Fish 

and Wildlife Service, Albuquerque, NM. 

Crist, L.W. and D.W. Ryden. 2003. Genetics management plan for the endangered fishes of the 

San Juan River. San Juan River Basin Recovery Implementation Program, U.S. Fish and 

Wildlife Service, Albuquerque, NM. 

Science Panel Report Final Report

A-3 
Appendix A: Science Panel Titles and Publications April 1, 2012 

Melissa Trammell 

Present Position: Fisheries Biologist, National Park Service, Salt Lake City, UT. 

Relevant Reports and Publications: 

Trammell, M., R.A. Valdez, S. Carothers, and R. Ryel. 2001. Effects of a low steady summer 

flow experiment on native fishes of the Colorado River in Grand Canyon, Arizona. 

Report of SWCA, Inc., Flagstaff, Arizona, to Grand Canyon Monitoring and Research 

Center, Flagstaff, AZ. 

Trammell, M., S. Meismer, and D. Speas. 2004. Nonnative cyprinid removal in the lower Green 

and Colorado rivers, Utah. Upper Colorado River Endangered Fish Recovery Program, 

Final Report Project 87A, Denver, CO. 

Trammell, M., and E. Archer. 2000. Chapter 4: evaluation of reintroduction of young of year 

Colorado pikeminnow in the San Juan River 1996-1998. Pages 4-1 to 4-33 in Archer, E., 

T.A. Crowl, and M. Trammell, editors. Age-0 native species abundances and nursery 

habitat quality and availability in the San Juan River, New Mexico, Colorado, and Utah. 

Utah Division of Wildlife Resources, Salt Lake City, UT. 

Speas, D., and M. Trammell. 2009. Aquatic habitat characteristics by river mile in lower Grand 

Canyon; preliminary results of 2009 field survey. Dave Speas, Bureau of Reclamation, 

and Melissa Trammell, National Park Service, Salt Lake City, UT. 

Speas, D., and M. Trammell. 2010. Razorback sucker habitat and options for repatriation 

experiments in lower Grand Canyon and the Lake Mead inflow area. [Powerpoint 

presentation.] Bureau of Reclamation and National Park Service, Salt Lake City, UT. 

Bestgen, K.R., G.B. Haines, R. Brunson, T. Chart, M. Trammell, R.T. Muth, G. Birchell, K. 

Christopherson, and J.M. Bundy. 2002. Status of wild razorback sucker in the Green 

River Basin, Utah and Colorado, determined from basinwide monitoring and other 

sampling programs. Draft Report of Colorado State University Larval Fish Laboratory to 

Upper Colorado River Endangered Fish Recovery Program, Denver, CO. 

Science Panel Report Final Report

A-4 
Appendix A: Science Panel Titles and Publications April 1, 2012 

Richard Valdez, Ph.D. 

Present Position: Senior Aquatic Ecologist, SWCA, Environmental Consultants, Logan, 

UT. 

Relevant Reports and Publications: 

Valdez R., T. Chart, T. Nesler, D. Speas, and M. Trammell. 2008. Yampa River nonnative fish 

control strategy. Upper Colorado River Endangered Fish Recovery Program, Denver, 

CO. 

Valdez, R.A. (Chairman), T. Chart, G. Burton, D. Irving, K. LaGory, R. Muth, H. Patno, and D 

Speas. 2006. Study plan for the implementation and evaluation of flow and temperature 

recommendations for endangered fishes in the Green River downstream of Flaming 

Gorge Dam. U.S. Fish and Wildlife Service, Region 6; Bureau of Reclamation, Upper 

Colorado Region; Western Area Power Administration, Salt Lake City, UT. 

Valdez, R.A. and R.T. Muth. 2005. Ecology and conservation of native fishes in the Upper 

Colorado River Basin, in J.N. Rinne, R.M. Hughes, and B. Calamusso (eds). Historical 

changes in large river fish assemblages of the Americas. American Fisheries Society,

Bethesda, MD. 

Valdez, R.A. and P. Nelson. 2004. Green River Floodplain Management Plan. Upper Colorado 

River Endangered Fish Recovery Program, Project No. C-6, Denver, CO. 

Webb, R.H., J.C. Schmidt, G.R. Marzolf, and R.A. Valdez (eds.). 1999. The Controlled Flood in 

Grand Canyon. Geophysical Monograph 110, American Geophysical Union, 

Washington, D.C. 

Schmidt, J.C., R.H. Webb, Valdez, R.A. Valdez, G.R. Marzolf, and L.E. Stevens. 1998. Science 

and values in river restoration in the Grand Canyon. BioScience 48(9): 735-747. 

Science Panel Report Final Report

A-5 
The Potential of Hab

The Potential of Hab

the Razorback Sucke

the Razorback Sucke

Lower Grand Can

Lower Grand Can

Richard Valdez

SWCA

and

Mark McKinstry Mark McKinstry

U.S. Bu U.S. Bureau of Reclam au of Reclamation
Outline Outline

 History of RBS in History of RBS in BiOps. RBS in Grand Canyon. RBS in Grand Canyon. Habitat of Lower GC and Lake M

Habitat of Lower GC and Lake M

 Significance of LGC Significance of LGC – LMI linkag

LMI linkag

 Recommendations. Recommendations.
1995 BiOp (Reclamation, Operation of Glen 

(Reclamation, Operation of Glen 

“...sponsoring a workshop sponsoring a workshop...of species exper

of species exper

management plan for the species in the Gr

management plan for the species in the Gr

Workshop: Jan 11-12, 1996 – Laughl

(72 attended)

 Dr. Harold Tyus (UC): Floodplains, nonnat

Dr. Harold Tyus (UC): Floodplains, nonnat

hydrograph. hydrograph.

 Dr. Paul Marsh (ASU): Predatory nonnative 

Dr. Paul Marsh (ASU): Predatory nonnativ

 Dr. Tom Dowling (ASU): Historical genetic 

Dr. Tom Dowling (ASU): Historical genetic 

to a single population. to a single population.

 Dr. Rich Valdez (B/W): Floodplains, cold wa

Dr. Rich Valdez (B/W): Floodplains, cold w

fish; 10 RBS (1944 fish; 10 RBS (1944-96).

 Mike Yard (GCES): Lower reach (RM 240 Mike Yard (GCES): Lower reach (RM 240-2

2

geomorphologically constrai geomorphologically constrained, Lake Mead 

ned, Lake Mead 
2006 BiOp (NPS-Colorado River Manag

Colorado River Manag

“...conduct surveys of backwaters and side cha

conduct surveys of backwaters and side cha

Gorge-Lake Mead interface, and that portion 

Lake Mead interface, and that portion 

project activities extend, for spawning razorb

project activities extend, for spawning razorb

Fish Sampling Diamond Cree

Pearce Ferry

 June 1992 June 1992 – January 1994 (Valdez 1994; Va

January 1994 (Valdez 1994; Va

 June – October 1997 (Hualapai Tribe & SW

October 1997 (Hualapai Tribe & SW

 2004 – 2006 (Ackerman et al. 2006; Ackerm

2006 (Ackerman et al. 2006; Ackerm

 2005 (Rogers et al. 2007). 2005 (Rogers et al. 2007). May 2009 (Speas and Trammell 2009). May 2009 (Speas and Trammell 2009). 2010 – 2012 (GCMRC, EL) 2012 (GCMRC, EL)—1 RBS at Surp

1 RBS at Surp
2007 BiOp (Reclamation, Shortages and 

(Reclamation, Shortages and 

Reservoir Operations) Reservoir Operations)— “...examine the pote

examine the pote

the lower Grand Canyon for the species, an

the lower Grand Canyon for the species, an

augmentation program in collaboration with FW

augmentation program in collaboration with FW

 Recon Trip of Cooperators: Reclam

Recon Trip of Cooperators: Reclam

USFWS, GCDAMP, MSCP, NPS, 

USFWS, GCDAMP, MSCP, NPS, 

NDOW, AGFD, Hualapai Tribe (S

NDOW, AGFD, Hualapai Tribe (S

 Science Panel (5 species experts) Science Panel (5 species experts) Three Reports Three Reports
Report #1: 

Review and Summary of 

Razorback Sucker 

Habitat in the Colorado 

River System

 Spawning, incubation, larval drift, nurseries, movement, diet, subadult and adult habitat. Used to gauge suitability of lower Grand Canyon and Colorado River inflow.
Report #2: Science Panel

The Potential of Habitat 

for the Razorback Sucker 

in the Lower Grand 

Canyon and Colorado 

River Inflow to Lake Mead

 Views, opinions, and recommendations of a Panel of species experts. Developed from recon field trip and meetings of Panel in September, 2010.
Report #3: 

Strategy for Establishing 

the Razorback Sucker in 

the Lower Grand Canyon 

and Lake Mead Inflow

 Strategy for establishment of the RBS in lower Grand Canyon. Naturally through expansion of the Lake Mead population orpossibly through augmentation.
Razorback Suckersin Grand Canyon

(1963 – 2012)

 10 adults

Carothers and Minckley 1984

Lower Grand Canyon

Max Elevation

(RM 235)

RM 280

RM 226
Why No RBS in Grand Canyon? Why No RBS in Grand Canyon?

Much of the Grand Canylooks like t

his !

No Floodplains 

for 300 miles

Most R

BS have been found near tributary infl

Paria River

Little Colorado 

River
The L

Grand 

Will RBS Continue Will RBS Continue 

to Use the LMI? to Use the LMI?

Photo Record:

 RBS larvae found in LMI in 2000-2001 RBS adults and larvae found startingin 2010 RBS found in LMI when lake elevation declinedNumbers of native suckers increased in ~2004

0%5%

10%15%20%25%

1992 1993 1994 1995 2004 2005 2006

Percent Composition

FM

SD

BH

Native Species

Valdez et al. 1995Ackermann et al. 2006
Separation Canyon (RM 240) Spencer Creek (R

Lava Cliff Rapid

June 24, 1992 (Valdez)

Salt Canyon (RM 255) Burnt Spring Ca

Above Quarterm
Below 

Quartermaster (RM 265)

Near Bat Cave 

June 24, 1992 (Valdez)

Above Emery Falls (RM 270) Above Pearce Fer
Spencer Creek (RM 246)

Lava Cliff Rapid

Backwater

September 18-19, 2010 (McAda)

Near Bat Cave (RM 265) Near Pearce Ferry 
Slide from Ke
Diamond Creek (RM 226) 1 Spencer Creek (R

September 18-19, 2010 (McAda)

Lake Mead Inflo

Salt Creek (RM 256) 3 (~10 mi below P
Nursery Habitat for RBS

3 Bars to Pearce Ferry Bay: Diamond Creek – 54 mi Spencer Canyon – 34 mi Salt Canyon – 24 mi1 Spawn Bar to Floodplains: Old Charlie Wash – 60 mi Leota Bottom – 52 mi Stewart Lake – 11 mi

3
Movement

Adults, Jun

SWCA)



6 fish rema

Surprise in w

river and lak

6 fish move

in 1997

• 12 fis

• 15 we

48 co

•

2 mov

down

• 60% o

or lak

Full Pool Lak

e Mead (~RM 237) Huala
Sig

Sig

 RBS P

RBS P

larges

larges

recruit

recruit

 3 meta

meta

fish m

fish m



4th me

me

 RBS fr

RBS fr

Grand 

Grand 

 Untagg

Untag

~Oct 6

~Oct 6

 Lower 

Lower 

import

import
Recommendatio

Recommendatio

 Phase I: Determine the presence of 

Phase I: Determine the presence of 

razorback suckers in the lower Gra

razorback suckers in the lower Gra

 Phase II: Assess and evaluate the vi

Phase II: Assess and evaluate the v

Lake Mead razorback sucker popul

Lake Mead razorback sucker popul

linkage to the lower Grand Canyon

linkage to the lower Grand Canyon

 Phase III: Determine the appropria

Phase III: Determine the appropria

augmentation program for the razo

augmentation program for the razo

in the lower Grand Canyon. in the lower Grand Canyon.