Reclamation Managing Water in the West

Strategy for Establishing the 

Razorback Sucker in the Lower 

Grand Canyon and Lake Mead Inflow

 
Cover Photos: 

Top center: aerial view of lower Grand Canyon (R. Valdez, June 24, 1992); top left: aerial view 

of Dexter National Fish Hatchery and Technology Center (U.S. Fish and Wildlife Service); 

bottom left: adult razorback sucker captured in the Upper Colorado River near Grand Junction 

(R. Valdez, June 1980); bottom right: view of the Colorado River through Grand Canyon from

Nankoweap Canyon, RM 52 (B. Masslich, 1990). 

Disclaimer: 

The opinions and recommendations expressed in this report are those of the authors 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., D.A. House, M.A. McLeod, and S.W. Carothers. 2012. Strategy for establishing 

the razorback sucker in the lower Grand Canyon and Lake Mead inflow, Report Number 3. Final 

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

Colorado Region, Salt Lake City, Utah. 

i 
Report Number 3 

STRATEGY FOR ESTABLISHING THE 

RAZORBACK SUCKER IN THE LOWER 

GRAND CANYON AND LAKE MEAD INFLOW

Final Report 

REPORT TO U.S. BUREAU OF RECLAMATION 

UPPER COLORADO REGION 

SALT LAKE CITY, UTAH 

REPORT BY SWCA ENVIRONMENTAL CONSULTANTS 

FLAGSTAFF, ARIZONA 

Richard A. Valdez, Dorothy A. House, 

Mary Anne McLeod, and Steven W. Carothers 

OCTOBER 1, 2012 

ii 
Preface October 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), 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 an augmentation strategy. 

This report is the third 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 to Lake Mead. 

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.

Strategy for Establishing the Razorback Sucker Final Report 

iii 
Acknowledgments October 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 

Strategy for Establishing the Razorback Sucker Final Report 

iv 
Table of Contents October 1, 2012 

TABLE OF CONTENTS

EXECUTIVE SUMMARY .........................................................................................................viii 

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

1.1 Background................................................................................................................... 1 

1.2 Species Status................................................................................................................ 1 

2.0 RECOMMENDED STRATEGY .......................................................................................... 3 

2.1 Phase I: Determine Presence and Use of Lower Grand Canyon .................................. 3 

2.2 Phase II: Assess and Evaluate Population Viability ..................................................... 6 

2.3 Phase III: Determine Appropriateness of Augmentation Program............................... 7 

Literature Cited ............................................................................................................................... 8 

APPENDIX A: CULTURE AND AUGMENTATION OF THE RAZORBACK SUCKER........ 1 

A-1.0 Introduction....................................................................................................... 1 

A-1.1 Genesis of Augmentation.................................................................................. 1 

A-1.2 Overview of Augmentation............................................................................... 2 

A-2.0 Propagation and Grow-Out Facilities ............................................................... 2 

A-2.1 Willow Beach NFH........................................................................................... 6 

A-2.2 Dexter NFHTC.................................................................................................. 6 

A-2.3 Ouray NFH........................................................................................................ 7 

A-2.4 Grand Valley Endangered Fish Facility............................................................ 7 

A-2.5 Wahweap State Fish Hatchery.......................................................................... 8 

A-2.6 Mumma Native Aquatic Species Restoration Facility...................................... 8 

A-2.7 Uvalde National Fish Hatchery......................................................................... 8 

A-2.8 Native Fish Work Group................................................................................... 8 

A-2.9 Navajo Agricultural Products Industry (NAPI) Ponds..................................... 9 

A-3.0 Propagation and Grow-Out Approaches........................................................... 9 

A-3.1 Broodstock Development Approach............................................................... 10 

A-3.2 Repatriation Approach.................................................................................... 12 

A-3.3 Translocation Approach.................................................................................. 13 

A-4.0 Transport and Release Methods...................................................................... 13 

A-4.1 Direct Release ................................................................................................. 13 

A-4.2 Acclimation..................................................................................................... 14 

A-5.0 History of Razorback Suckers Released......................................................... 14 

A-5.1 Lower Colorado River Basin .......................................................................... 14 

A-5.2 Upper Colorado River Basin........................................................................... 16 

A-6.0 Survival of Razorback Suckers Released ....................................................... 19 

A-6.1 Lower Colorado River Basin .......................................................................... 19 

A-6.2 Upper Colorado River Basin........................................................................... 20 

A-7.0 Evaluation of Culture and Augmentation Methods........................................ 22 

Literature Cited ............................................................................................................................. 25

Strategy for Establishing the Razorback Sucker Final Report

v 
List of Tables October 1, 2012 

LIST OF TABLES 

Table A-1. Existing major propagation facilities or programs for the razorback sucker (RBS), 

their principal role in species conservation, the numbers of broodstock fish on-site, and 

approximate miles of highway distance to Diamond Creek, the principal road access 

point to the lower Grand Canyon. ................................................................................... 4 

Table A-2. Numbers of razorback suckers stocked annually into the Lower Colorado River 

Basin (1980-2004), mean total length (TL), and estimated number of first-year 

survivors. Table adopted from Schooley and Marsh (2007)......................................... 15 

Table A-3. Numbers of razorback suckers stocked annually into the Colorado, Gunnison, and 

Green rivers (1995–2010) and numbers recaptured. Source: Upper Colorado River 

Endangered Fish Recovery Program............................................................................. 17 

Table A-4. Numbers and sizes of razorback suckers stocked annually into the San Juan River 

(1994-2008). Table from Furr and Davis (2009). ......................................................... 18 

Table A-5. Description and evaluation of propagation, grow-out, and release methods for the 

razorback sucker............................................................................................................ 23 

Strategy for Establishing the Razorback Sucker Final Report

vi 
List of Figures October 1, 2012 

LIST OF FIGURES 

Figure 1. Historical and present distribution of the razorback sucker with designated critical

habitat in the Colorado River System (adopted from Maddux et al. 1993 and Schooley 

and Marsh 2007). A detailed inset map of the Lower Grand Canyon from Diamond 

Creek to Pearce Ferry is provided. .................................................................................. 2 

Figure A-1. Locations of eight major propagation facilities for the razorback sucker relative to 

the Colorado River System. The ninth location at the Uvalde National Fish Hatchery 

near Uvalde, Texas is not shown..................................................................................... 3 

Figure A-2. Total numbers and mean total lengths (shown above bars) of razorback suckers 

stocked in the Lower Colorado River Basin, 1980-2004. See Table 2 for details on 

numbers and fish lengths............................................................................................... 16 

Figure A-3. Total numbers of razorback suckers stocked in the Upper Colorado River Basin, 

1995-2010. See Table 3 for details on numbers............................................................ 17 

Figure A-4. Total numbers and mean total lengths of razorback suckers stocked in the San Juan 

River, 1994-2008. See Table 4 for numbers and fish lengths....................................... 18 

Figure A-5. First-year survival curve as a function of total length at release for repatriated 

razorback suckers that were recaptured as adults during annual March censuses in Lake 

Mohave, Arizona-Nevada, 1992-2002. Survival is shown for lengths of 300, 350, 400, 

and 500 mm TL. Figure reproduced from Marsh et al. (2005). .................................... 19 

Figure A-6. Total length (TL)-dependent, 1st-interval (ry1) and subsequent-interval (post-ry1) 

survival rate estimates for razorback suckers reared by three methods and stocked into 

the Upper Colorado River Basin, Utah and Colorado, 2004–2007. Interpolated survival 

rates are shown for lengths of 300, 350, 400, and 500 mm TL. Figure reproduced from 

Zelasko et al. (2011)...................................................................................................... 21 

Strategy for Establishing the Razorback Sucker Final Report

vii 
Executive Summary October 1, 2012 

EXECUTIVE SUMMARY 

The U.S. Bureau of Reclamation (Reclamation), in collaboration with the U.S. Fish and Wildlife 

Service (USFWS), is investigating the potential for establishment of the endangered razorback 

sucker (Xyrauchen texanus) in the lower Grand Canyon. This report describes a strategy for 

establishing the species through three phases: Phase I: Determine the presence of and use by 

razorback suckers in the lower Grand Canyon; Phase II: Assess and evaluate the viability of the 

Lake Mead razorback sucker population and its linkage to the lower Grand Canyon; and Phase 

III: Determine the appropriateness of an augmentation program for the razorback sucker in the 

lower Grand Canyon. Phase I consists for four tasks including: (1) continued use of telemetry, 

(2) reconnaissance of the large-bodied fish community, (3) characterization of the small-bodied 

fish community, and (4) a description of patterns of larval sucker occurrence and habitat use. 

Phase II is a recommended Population Viability Analysis (PVA) that can be used to evaluate the 

need and appropriateness of an augmentation program for the razorback sucker in the lower 

Grand Canyon by adding fish of different sizes and ages to the population with various survival 

rates to assess the effect on the overall adult population and future reproductive and recruitment 

potential. Phase III is a decision process in which Reclamation and the USFWS may render the 

decision to institute an augmentation program for the razorback sucker in the lower Grand 

Canyon, if appropriate. 

 . 

Strategy for Establishing the Razorback Sucker Final Report

viii 
1.0 Introduction October 1, 2012 

1.0 INTRODUCTION 

1.1 Background 

This report recommends a strategy for establishing the federally endangered razorback sucker 

(Xyrauchen texanus) in the Colorado River through the lower Grand Canyon and Lake Mead 

inflow (Figure 1). It consists of three phases that determine the extent of use of the area by the 

species; evaluate the viability of the population in the region; and helps to determine the need for 

instituting an augmentation program for the razorback suckers in the area.

This strategy was developed from information gleaned from a review of habitat used by the 

species in other regions of the Colorado River System (Valdez et al. 2012a) and from the input of 

a Science Panel (Valdez et al. 2012b). Since that information was assimilated, sonic-tagged 

razorback suckers from Lake Mead were detected in spring and early summer of 2012 upstream

from the Lake Mead inflow and in the lower Grand Canyon up to and around Quartermaster 

Canyon, about 20 mi upstream from Pearce Ferry (Kegerries and Albrecht 2012). Rising lake 

levels in 2012 inundated the Pearce Ferry rapid and evidently facilitated upstream fish 

movement, although the lower Grand Canyon had not been previously monitored with telemetry 

and fish using the area could have gone undetected. 

The information contained in this report may be used by the U.S. Bureau of Reclamation 

(Reclamation) in collaboration with the U.S. Fish and Wildlife Service (USFWS) to institute an 

augmentation program for the razorback sucker, as deemed necessary and appropriate (see 

Reclamation 2007; USFWS 2007). This report and the two companion reports cited above are 

designed to assist Reclamation and the USFWS in determining if augmentation of the razorback 

sucker is appropriate or feasible for establishing the species in the lower Grand Canyon. 

1.2 Species Status 

The razorback sucker was recognized as an imperiled species in the early 1900s (Minckley 

1983), and initial efforts to conserve the species were conducted locally by State and Federal 

agencies together with volunteer efforts (Minckley et al. 1991). The razorback sucker was listed 

as “endangered” under the Endangered Species Act of 1973, as amended (ESA; 16 U.S.C. 1531 

et. seq.) on October 23, 1991 (56 FR 54957) with critical habitat designated on April 20, 1994 

(59 FR 13374). A recovery plan was approved on December 23, 1998 (USFWS 1998) and 

Recovery Goals were approved on August 1, 2002 (USFWS 2002). 

Critical habitat was designated in 1994 as 2,776 km (1,724 mi; Figure 1) of the Colorado River 

and its tributaries in the upper and lower basins. This designation laid the foundation for 

potential population restoration sites, and the Razorback Sucker Recovery Plan (USFWS 1998) 

called for protecting and restoring habitat, augmenting or establishing populations with cultured 

fish, and maintaining existing genetic diversity. These concepts were carried forward into the 

2002 Recovery Goals (USFWS 2002) that require four genetically and demographically viable, 

self-sustaining populations (established or augmented with hatchery stocks), including two each 

in the upper and lower Colorado River basins. 

Strategy for Establishing the Razorback Sucker Final Report 

1 
1.0 Introduction October 1, 2012 

Figure 1. Historical and present distribution of the razorback sucker with designated critical habitat in the 

Colorado River System (adopted from Maddux et al. 1993 and Schooley and Marsh 2007). A detailed inset 

map of the Lower Grand Canyon from Diamond Creek to Pearce Ferry is provided. 

Strategy for Establishing the Razorback Sucker Final Report 

2 
2.0 Recommended Strategy October 1, 2012 

2.0 RECOMMENDED STRATEGY 

The following is a recommended strategy for establishing the razorback sucker in the lower 

Grand Canyon and Lake Mead inflow. The strategy consists of three phases: 

1. Phase I: Determine the presence of and use by razorback suckers in the lower Grand 

Canyon; 

2. Phase II: Assess and evaluate the viability of the Lake Mead razorback sucker 

population and its linkage to the lower Grand Canyon; and 

3. Phase III: Determine the appropriateness of an augmentation program for the 

razorback sucker in the lower Grand Canyon. 

2.1 Phase I: Determine Presence and Use of Lower Grand 

Canyon 

The presence of razorback suckers in the lower Grand Canyon was confirmed when five unique 

fish were detected at two Submersible Ultrasonic Receivers (SURs) upstream of Pearce Ferry in 

spring and summer of 2012. These SURs were placed and monitored by Bio/West starting in 

spring 2012 (Kegerries and Albrecht 2012). The SURs were placed at the Pearce Ferry boat 

ramp (RM 280), Bat Cave (RM 267) and Quartermaster Canyon (RM 260). The fish detected at 

these SURs had been sonic-tagged in Lake Mead in July and August of 2011 (a detailed 

Bio/West report was not available at the time of this document). Three of these fish were first 

detected between Pearce Ferry and the Grand Wash inflow starting in February 2012. These fish 

remained upstream of Pearce Ferry until May or June 2012 and then moved back downstream

into the Lake Mead inflow and lake proper. 

The numbers of razorback suckers in the lower Grand Canyon upstream of Pearce Ferry is 

unknown. The telemetered fish detected in early 2012 were fish from Lake Mead that may have 

been exploring new available habitats following a rise in lake elevation. Possibly movement into 

the lower Grand Canyon is part of a regular life history pattern by some Lake Mead fish that 

have gone undetected for lack of telemetry monitoring in the area. It is also possible that some

razorback suckers are residents of the lower Grand Canyon and use the lake inflow as part of 

their life history. The Lake Mead razorback sucker population is the largest known reproducing 

population, and understanding the linkage in use of Lake Mead and the lower Grand Canyon 

may be vital for conserving and possibly expanding this population. 

As the first phase of this strategy, it is important to understand the extent of use by the razorback 

sucker of the lower Grand Canyon and to estimate the numbers of fish in the area. The following 

tasks are recommended: 

1. Continued Use of Telemetry. 

Sonic tags are currently being used effectively to monitor movements of razorback suckers in 

Lake Mead (e.g., Albrecht et al. 2010). Sonic tags may not be as effective as radio tags in the 

Strategy for Establishing the Razorback Sucker Final Report 

3 
2.0 Recommended Strategy October 1, 2012 

riverine environment of the lower Grand Canyon, and it may be necessary to use a combination 

sonic and radio telemetry for monitoring fish moving between the lake and the river. The most 

appropriate tags and telemetry systems should be determine by scientists working in the region 

and most knowledgeable with this technology. Telemetry should continue to be used as a tool 

to: 

a. Detect fish moving upstream from the Lake Mead population: Given that there 

is an ongoing effort to sonic-tag razorback suckers in Lake Mead, active and 

passive monitoring should be done in the lower Grand Canyon as far upstream as 

Lava Falls rapid to determine the extent of movement by fish from the lake into the 

river. Passive monitoring should include the establishment of multiple 

strategically-located SURs for detecting year-around movement. Active monitoring 

should also be done by crews in the area to assess habitat use, daily movements, and 

fish associations. 

b. Determine if razorback suckers in the lower Grand Canyon are transient or 

resident: The fish detected above Pearce Ferry in 2011-2012 remained in the lower 

Grand Canyon for about 5 months (February through June). It is important to 

determine if the lower Grand Canyon is being used seasonally by fish from Lake 

Mead possibly for feeding and/or spawning; or if there are fish in the lower Grand 

Canyon as permanent residents. It may be appropriate to translocate telemetered 

fish from captivity (e.g., Floyd-Lamb) into the lower Grand Canyon to supplement 

the numbers of known fish in the area and to determine if fish will remain in the 

lower Grand Canyon. If appropriate, 10–15 fish should be translocated and released 

as far upstream as Lava Falls rapid, or in pools adjacent to potential spawning bars 

at Diamond Creek, Spencer Canyon, and Salt Creek. The fish should be tracked 

immediately after release to determine if they will remain in the area or move 

downstream to the lake. These fish can also be used to locate other razorback 

suckers associated in preferred habitats. Releasing razorback suckers upstream of 

Lava Falls rapid is not recommended because of the lack of a full complement of 

suitable habitat for the species and the great distance for drifting larvae to known 

nursery habitat in the Lake Mead inflow. Use of wild telemetered fish from Lake 

Mead is not advised, although “wild” fish caught in the lower Grand Canyon should 

be considered for telemetry. 

c. Locate additional razorback suckers: Telemetry should be used in tandem with 

sampling for large-bodied fish. Telemetered fish can be used as “Judas fish” to 

reveal the possible presence of other razorback suckers aggregated in the same area. 

d. Document habitat use in the lower Grand Canyon: Habitat used by various life 

stages of the razorback sucker in the lower Grand Canyon should be documented. 

If fish from Lake Mead are using this area for feeding and/or spawning, it will be

important to determine if these areas need protection or may be enhanced. 

Understanding if spawning is occurring in the lower Grand Canyon and the habitats 

used for spawning and larval rearing is also important in providing a better 

understanding of the linkage between Lake Mead and the Colorado River inflow in 

the conservation and recovery of the species. 

Strategy for Establishing the Razorback Sucker Final Report 

4 
2.0 Recommended Strategy October 1, 2012 

2. Reconnaissance Large-Bodied Fish Community. 

The primary purpose of this task should be to reconnaissance the fish species in the area, 

determine relative abundances, determine the proportion of native suckers in the area (razorback, 

flannelmouth, and bluehead), and estimate the numbers of razorback suckers in the lower Grand 

Canyon. Selective sampling should be done for large-bodied fish from Lava Falls rapid to 

Pearce Ferry (RM 169-280). The most effective gear types are trammel nets and large hoop nets 

set continuously and for several days in select habitats. These should be placed in the most 

likely habitats and used in tandem with and in proximity of telemetered fish. The razorback 

sucker is a social species and there is a good chance that telemetered fish may be accompanied 

by other un-tagged fish. Electrofishing is not considered very effective for capturing razorback 

suckers in a turbid riverine environment, and extensive use of this gear in the lower Grand 

Canyon is not advised. 

All fish captured should be recorded to species, and lengths and weights of samples should be 

recorded. Native fish should be permanently marked consistent with ongoing Lake Mead and 

Grand Canyon protocols for fish monitoring. This sampling should be coordinated with annual 

sampling by the Grand Canyon Monitoring and Research Center (GCMRC) below Diamond 

Creek and with the Lake Mead Razorback Sucker Work Group below Pearce Ferry. Where 

possible, the numbers of native suckers should be estimated with mark-recapture methods, or at 

least catch-per-effort should be recorded as numbers of fish per 10 hours of trammel nets or hoop 

nets set. This reconnaissance should also establish the proportional age categories for each 

native sucker to better understand how the lower Grand Canyon is used by these species (e.g., for 

spawning, nursing, rearing, feeding). 

3. Characterize Small-Bodied Fish Community. 

The primary purpose of this task is to determine if young native suckers, particularly the 

razorback sucker, are rearing in the lower Grand Canyon. Intensive seining is recommended in 

backwaters and other shallow, sheltered habitats that may support juvenile suckers. The 

numbers of flannelmouth and bluehead suckers in the Grand Canyon has increased since about 

2004, and possibly razorback suckers are aggregated with these related species in key habitats 

(see Valdez et al. 2012a). All fish captured should be recorded to species and lengths and 

weights of samples should be recorded. Native fish of suitable size should be permanently 

marked consistent with ongoing Lake Mead and Grand Canyon protocols for fish monitoring. 

The relative abundance of native suckers should be estimated with catch-per-effort as numbers of 

fish per 100 m2

 seined. 

4. Describe Patterns of Larval Sucker Occurrence and Habitat Use. 

Larval and post-larval fish sampling should be conducted from Lava Falls rapid to Pearce Ferry 

to identify fish species spawning in the area, possible spawning locations, timing of spawning, 

and numbers of young produced in the area as well as entering and leaving the lower Grand 

Canyon. Larval and post-larval fish should initially be collected once a month for about 7 months 

(February–July) from different habitats (shorelines, backwaters, etc.) to document species 

presence and habitat use. Once the timing of spawning by razorback suckers is established for 

Strategy for Establishing the Razorback Sucker Final Report 

5 
2.0 Recommended Strategy October 1, 2012 

the lower Grand Canyon, the window of sampling should be narrowed accordingly. Larval fish 

sampling in the lower Grand Canyon should be coordinated with larval fish sampling in the Lake 

Mead inflow. 

2.2 Phase II: Assess and Evaluate Population Viability 

Ongoing work with the razorback sucker in Lake Mead demonstrates the connectivity between 

groups of fish in Lake Mead and a possible linkage to the Colorado River in lower Grand 

Canyon (Albrecht et al. 2010; Kegerries and Albrecht 2012). The possible connection between 

Lake Mead and the lower Grand Canyon as part of the life history of fish in the region is 

significant with respect to conservation and recovery of the razorback sucker. The Colorado 

River is the largest inflow to Lake Mead and understanding its role and importance to the 

species—given the discovery of telemetered fish in lower Grand Canyon in 2012—now becomes 

an important aspect of future investigations for the species in this area of the Colorado River 

Basin. 

The numbers of razorback suckers in apparent metapopulations in Lake Mead (i.e., Las Vegas 

Bay, Echo Bay, and the Muddy River/Virgin River inflow area) have been estimated and some

of the vital demographic parameters (e.g., adult survival, recruitment to adults) have been 

determined. However, specific variables that most influence population size are not well 

understood (e.g., age-specific survival, lake elevation as it affects habitat, etc.). Confirmed 

spawning at the Colorado River inflow in 2010, 2011, and 2012 and collection of larvae in the 

inflow indicate that a fourth metapopulation is present with possible linkages to the Colorado 

River in the lower Grand Canyon. There has been a considerable amount of information 

collected on the vital demographic parameters for each of the four apparent metapopulations and 

the extent of connectivity between and among them has been documented with telemetry. 

However, the importance of each of these groups of fish to the long-term viability of the greater 

Lake Mead population cannot be readily evaluated without the aid of a population model that can 

assemble the available information into a comprehensive evaluation of long-term population 

viability. 

Population viability analysis (PVA) has become a common tool for assessing the viability and 

risk of extinction for many endangered and threatened species (e.g., Beissinger and McCullough 

2002). Age-structured stock-recruitment models are often used as the centerpiece of these PVAs 

to assess the impact of various management scenarios on species viability, including population 

augmentation. A PVA has not been developed for the razorback sucker and there are no recent 

models that have been developed for similar sucker species, although a population simulation 

model was developed for the cui-ui (Chasmistes cujus) (Emlen et al. 1993). Nevertheless, the 

expertise and technology for developing a PVA is readily available, including commercial 

software (e.g., RAMAS Metapop; Applied Biomathematics, Setauket, NY). 

Population viability analysis is a meaningful and useful tool for better understanding the 

dynamics of the Lake Mead razorback sucker population and the relationship of this population 

to the lower Grand Canyon, as well as the efficacy of an augmentation program for population 

enhancement and species recovery. An age-structured stock-recruitment model will require vital 

demographic parameters, including age composition, age-specific survival, recruitment, 

Strategy for Establishing the Razorback Sucker Final Report 

6 
2.0 Recommended Strategy October 1, 2012 

maternity, estimated species abundance, and linkages among metapopulations. These vital 

demographic parameters are important for understanding populations and should be quantified as 

part of ongoing investigations of the razorback sucker. 

2.3 Phase III: Determine Appropriateness of Augmentation 

Program

An augmentation program for the razorback sucker in the lower Grand Canyon cannot be 

developed at this time because the status of the species in the area is unknown and the prospect 

for expanding the Lake Mead population is uncertain (see Valdez et al. 2012b). Phase I of this 

strategy is designed to determine the extent of use by the species of the lower Grand Canyon and 

the approximate numbers of fish involved. Phase II is a recommended population viability 

analysis that should provide the tool for better understanding the linkages among Lake Mead 

metapopulations and the role and appropriateness of an augmentation program for the lower 

Grand Canyon. Phase III should consist of an assimilation of information and an ongoing 

dialogue among the collaborators to ensure a timely decision to determine if an augmentation 

program will be necessary and appropriate. 

As the information is brought together that assesses the viability of the razorback sucker 

population in this region of the Colorado River, Reclamation and the USFWS should continue to 

coordinate activities and the decision to institute an augmentation program. This decision should 

be made in collaboration with the 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. 

Appendix A of this report has been assembled to bring together information on the culture of the 

razorback sucker and the history of releasing of these fish to augment wild populations or 

reestablish the species in historic habitat. This appendix and the Science Panel Report (see 

Valdez et al. 2012b) are provided as an insight into the issues that may surround development of 

an augmentation program and the release of fish into the lower Grand Canyon. 

 

Strategy for Establishing the Razorback Sucker Final Report 

7 
Literature Cited October 1, 2012 

LITERATURE CITED 

Albrecht, B., R. Kegerries, P. Holden, and R. Rogers. 2010. Razorback sucker investigations at 

the Colorado River inflow area, Lake Mead, Nevada and Arizona. 2010 Final Annual 

Report, Bio/West, Inc., Logan, UT to Bureau of Reclamation, Lower Colorado Region, 

Boulder City, NV. 

Beissinger, S.R. and D.R. McCullough (editors). 2002. Population viability analysis. The 

University of Chicago Press, Chicago, IL. 

Emlen, J.A., T.A. Streckel, and C.C. Buchanan. 1993. Probabalistic projections for recovery of 

the endangered cui-ui. North American Journal of Fisheries Management 13:467-474. 

Kegerries, R., and B. Albrecht. 2012. Razorback sucker studies at the Colorado Inflow of Lake 

Mead, Nevada and Arizona – 2012. Power-Point presentation at the Fall 2012 Meeting of 

the Lake Mead Razorback Sucker Work Group, October 2, 2012, Las Vegas, NV. 

Maddux, H.R., L.A. Fitzpatrick, and W.R. Noonan. 1993. Colorado River endangered fishes 

critical habitat. U.S. Fish and Wildlife Service, Salt Lake City, UT 

Minckley, W.L. 1983. Status of the razorback sucker, Xyrauchen texanus (Abbott), in the Lower 

Colorado River Basin. The Southwestern Naturalist 28(2): 165–187. 

Minckley, W.L., P.C. Marsh, J.E. Brooks, J.E. Johnson, and B.L. Jensen. 1991. Management 

toward recovery of the razorback sucker. Pages 303–357 in W.L. Minckley and J.E. 

Deacon, eds. Battle against extinction: native fish management in the American West. 

University of Arizona Press, Phoenix, AZ. 

Reclamation (U.S. Bureau of Reclamation). 2007. Biological assessment of the Colorado River 

interim guidelines for lower basin shortages and coordinated operations for Lake Powell 

and Lake Mead, Final Environmental Impact Statement. Bureau of Reclamation, Boulder 

Canyon Operations Office, Boulder City, NV. 

Schooley, J.D., and P.C. Marsh. 2007. Stocking of endangered razorback suckers in the lower 

Colorado River Basin over three decades: 1974–2004. North American Journal of 

Fisheries Management 27: 43–51. 

USFWS (U.S. Fish and Wildlife Service). 1998. Razorback sucker Xyrauchen texanus recovery 

plan. U.S. Fish and Wildlife Service, Region 6, Denver, CO. 

USFWS (U.S. Fish and Wildlife Service). 2002. Razorback sucker (Xyrauchen texanus) recovery

goals: amendment and supplement to the razorback sucker recovery plan. U.S. Fish and 

Wildlife Service, Mountain-Prairie Region 6, Denver, CO. 

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. 

Strategy for Establishing the Razorback Sucker Final Report 

8 
Literature Cited October 1, 2012 

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., C. McAda, G. Mueller, D. Ryden, and M. Trammell. 2012b. 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, UT. 

Strategy for Establishing the Razorback Sucker Final Report 

9 
Appendix A: Culture and Augmentation October 1, 2012 

APPENDIX A: CULTURE AND AUGMENTATION 

OF THE RAZORBACK SUCKER 

A-1.0 Introduction 

This appendix has been assembled to bring together information on the culture of the razorback 

sucker and the release of these fish to augment wild populations or reestablish the species in 

historic habitat. The genesis of augmentation is described, as well as an overview of the history 

of hatchery culture for the species. This appendix identifies the propagation and grow-out 

facilities, and the approaches and methods used for propagation and augmentation. Also, a 

history of the numbers of fish released and their survival rates are provided as insight on those 

methods that have shown to be the most successful. 

A-1.1 Genesis of Augmentation 

Listing of the species in 1991 resulted in more widespread and coordinated efforts toward 

conservation, including the stocking of fish to establish new populations and augment existing 

ones. A status review of the species (Bestgen 1990) revealed extensive range reduction, losses of 

populations, and declining numbers of individuals throughout its remaining distribution, with the 

largest remaining numbers in Lake Mohave and the upper Green River. This status review 

recommended the development of a hatchery broodstock and refugia population, but cautioned 

that simply stocking large numbers of razorback suckers into a variety of existing habitats would 

not recover the species; rather, controlled experiments would be needed to better understand the 

limiting factors for natural recruitment and necessary habitat. 

Listing the razorback sucker also raised the level of species protection and conservation with the 

establishment of five major conservation programs in the Colorado River System (USFWS 

2002), including: (1) Upper Colorado River Endangered Fish Recovery Program (UCRRP), (2) 

San Juan River Basin Recovery Implementation Program (SJRIP), (3) Glen Canyon Dam

Adaptive Management Program (GCDAMP), (4) Native Fish Work Group (NFWG), and (5) 

Lower Colorado River Multi-Species Conservation Program (MSCP). Each of these programs 

conducts and supports activities that include augmentation of existing or new populations with 

fish raised in captivity. 

As part of the effort to restore populations of razorback suckers in the wild, the USFWS has 

included stocking fish as part of the requirement of Section 7 compliance under the ESA. Under 

the terms of a Biological Opinion for Lower Colorado River operations and maintenance 

(USFWS 1997), Reclamation was required, by the year 2000, to annually stock 50,000 adult 

razorback suckers in Lake Mohave and 25,000 in Lake Havasu. These activities were conducted 

and coordinated by the NFWG and MSCP. An evaluation of long-term survival of these stocked 

fish has revealed new strategies for improving successes of these stocks (see section 2.4). 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

A-1.2 Overview of Augmentation 

Razorback suckers have been raised in captivity since the early 1970s (Toney 1974; Inslee 1981) 

and used to augment declining populations in many parts of the Colorado River System (e.g., 

Creef et al. 1992; Creef and Clarkson 1993; Hendrickson 1993; Carmichael et al. 1996; Foster 

and Mueller 1999; Modde and Haines 2005; Mueller and Burke 2005). Propagation techniques 

for the species have been developed and refined, and culture facilities have the capability and 

capacity to raise large numbers of fish in captivity. Initially, millions of small razorback suckers 

were stocked into rivers and reservoirs of the Colorado River System, but low survival rates have 

led to a refinement of propagation, grow-out, and release methods. Recently, there has been a 

transition from stocking large numbers of small fish toward stocking fewer larger fish that have a 

higher rate of survival (e.g., Mueller 1995; Modde et al. 1995; Ryden 1997; Burdick 2003; 

Schooley and Marsh 2007; Zelasko et al. 2009, 2010). 

Ongoing concerns over maintaining genetic viability, fitness of fish to the receiving waters, 

imprinting to local habitats, and losses to predation and competition from nonnative fishes have 

also lead to a continued and ongoing evaluation and refinement of rearing and release methods. 

These propagation, grow-out, and release methods continue to be refined based on ongoing 

investigations and new approaches are being tested in the hatcheries and in the field. The 

following section describes the development of these methods and the refinements. 

A-2.0 Propagation and Grow-Out Facilities 

Nine major facilities or programs currently propagate, grow out, and release the razorback sucker 

(Figure 1). Fish raised in these facilities are used to reestablish populations in historical range, 

augment existing populations, and for research. Seven of these facilities are located within the 

Colorado River System and two (Dexter NFHTC and Uvalde NFH) are located outside of the 

drainage. 

The basic information associated with each facility is presented in Table A-1, including the 

approximate numbers of broodstock fish on-site. Some of these facilities have been in operation 

for a number of years and have transferred fish to and from various locations. Altogether, about 

15 million razorback suckers have been stocked from these facilities into the wild since about 

1980. 

The specific numbers of fish produced and stocked from each facility are not provided, but can 

be procured from records for each site. Other facilities have in the past propagated the razorback 

sucker and a number of research institutions have held or currently hold the species; e.g., Lake 

Havasu Fishery Improvement Project, Boulder City Golf Course Native Fish Rearing Project, 

Hualapai Native Fish Rearing Facility. These facilities are not described herein, other than to 

identify propagation or release methods that may apply to the lower Grand Canyon. 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

Strategy for Establishing the Razorback Sucker Final Report 

A-3 

Figure A-1. Locations of eight major propagation facilities for the razorback sucker relative to the Colorado

River System. The ninth location at the Uvalde National Fish Hatchery near Uvalde, Texas is not shown.
Appendix A: Culture and Augmentation 

Table A-1. Existing major propagation facilities or programs for the razorback sucker (RBS), their principal role in species conof broodstock fish on-site, and approximate miles of highway distance to Diamond Creek, the principal road access point to th

Facility Agency Year Started Primary Role for RBS Recent RBS Broodst

Willow Beach National FishHatchery 

U.S. Fish and Wildlife Service 

1974 First native fish hatchery for Southwest U.S. 

Spawners taken from Lake Mohave, spawned, and returned. 

Variable numbers of wifish from Lake Mohave 

Dexter NFHTC U.S. Fish and 

Wildlife Service 

1981 Primary native fish hatchery for Southwest U.S. 

endangered fish species. Produce young RBS from broodstock for stocking throughout System. 

~300 adults from primaLake Mohave

Ouray National FishHatchery 

U.S. Fish and Wildlife Service 

1986 Established to preserve unique genetics of wild

Green River fish. Fish produced are stocked in Green River. 

~660 adults from GreenColorado, San Juan rive

Grand Valley Endangered FishFacility 

U.S. Fish and Wildlife Service 

1992 Production meets stocking goals for Gunnison, 

Upper Colorado, and San Juan rivers. Alsoprovide fish for NAPI grow-out ponds. 

~300 adults; mix from Upper Colorado, GreenSam Juan rivers, Etter Pond, Willow BeachIMohave

Wahweap State Fish Hatchery 

Utah Division of Wildlife Resources 

1993 Maintains back-up broodstock for Green River 

fish for Ouray NFH; fish not spawned on site. 

~925 adults; back-upbroodstock for Green Rfish from Ouray NFH 

J.W. Mumma NativeAquatic Species Restoration Facility 

Colorado Department of Wildlife 

2000 Primarily a grow-out facility for fish received from 

other sources; fish not spawned on site. 

No broodstock; primarilgrow-out facility 

Uvalde National FishHatchery 

U.S. Fish and Wildlife Service 

2006 Functions as a grow-out facility for larvae 

spawned at Dexter NFHTC 

No broodstock; grow-oufacility only with target o11,400, 300 mm RBS fostocking San Juan Rive

Strategy for Establishing the Razorback Sucker  A-4 
Appendix A: 

Strategy fo A-5 

Culture and Augmentation 

r Establishing the Razorback Sucker 

Facility Agency Year Started Primary Role for RBS Recent RBS Broodst

Native Fish WorkGroup 

U.S. Bureau ofReclamation 

1990 Established to prevent disappearance of RBS 

from Lake Mohave. Collect wild larvae from reservoir for grow-out in sanctuary coves and ponds. 

Annually collect wild larfrom Lake Mohave

Navajo AgriculturalProducts Industry (NAPI) Ponds 

Navajo Nation No broodstock; primaril

grow-out ponds with tarof 6,000, 300 mm RBS stocking San Juan Rive
Appendix A: Culture and Augmentation October 1, 2012 

A-2.1 Willow Beach NFH 

The Willow Beach National Fish Hatchery (NFH) was the first facility to hold the Colorado 

River endangered species. It was built in 1962 about 11 mi downriver from Hoover Dam. The 

facility uses cold water from the dam and raises primarily rainbow trout (Oncorhynchus mykiss) 

for stocking in nearby lakes Mohave and Mead as mitigation for the construction of the dams of

the Lower Colorado River. Although trout are still stocked from the hatchery to provide 

recreational fishing opportunities, imperiled fishes like the razorback sucker and bonytail (Gila 

elegans) are also propagated or held on site for research and for release to the wild. 

Willow Beach NFH was the first hatchery to receive razorback suckers from the wild in the early 

1970s (Toney 1974; Inslee 1981). On March 27, 1974, a joint Federal-State Recovery Team

collected 40 adults near Cottonwood Cove, Lake Mohave and transported them live to the 

Willow Beach NFH (Valdez 1985). Some eggs were stripped and collected on site and moved 

with the fish to Willow Beach. On May 7, 1974, 32 of these fish were transferred to the Arizona 

State Fish Hatchery at Page Springs. The progeny of these fish were used for research and for 

release back to the wild. Much of the responsibility for raising Colorado River endangered fish 

was transferred from the Willow Beach NFH to the Dexter NFHTC in the 1980s. 

Willow Beach NFH currently receives ripe adult razorback suckers from Lake Mohave, spawns 

the fish on site, and transfers the progeny to grow-out ponds in the lower basin. The facility 

houses a variable number of wild razorback suckers from Lake Mohave, depending on time of 

year, but does not house a broodstock. 

A-2.2 Dexter NFHTC 

The Dexter National Fish Hatchery and Technology Center (NFHTC) is located in the Pecos 

River Basin in southeastern New Mexico. The NFHTC houses a Fish Culture Facility, Molecular 

Ecology Lab, and Fish Health Unit. In 2011, the center held over 1 million individuals of 15 

different threatened and endangered fish species. The Dexter NFHTC works with partners to 

reintroduce species into their native habitats; improve the quality of fish reared through genetic 

research; and maintain populations in the event of catastrophic loss in the wild. 

The Dexter National Fish Hatchery was established in 1932 to meet the demands for warm water 

sport fishing in the southwest. With passage of the ESA in 1973, there began a growing demand 

for propagation of threatened and endangered fishes, and the mission of the facility was 

transitioned from raising fish for recreational purposes to propagating, housing, and protecting 

imperiled fish species; the Dexter NFH became the Dexter NFHTC in 1984. 

The Dexter NFH began work with the razorback sucker in January of 1981 and 1982 when 134 

and 147 wild adults from Lake Mohave were transferred from Willow Beach NFH (Minckley 

and Brooks 1985). These fish became the basis for development of a broodstock at that facility, 

and some of these fish remain there today. From 1981 to 2004, the Dexter NFH and NFHTC 

produced more than 15 million razorback suckers (Dexter NFHTC, unpublished data, 2004, cited 

in Mueller 2006). Dexter NFHTC maintains a broodstock of about 300 razorback suckers and 

Strategy for Establishing the Razorback Sucker Final Report 

A-6 
Appendix A: Culture and Augmentation October 1, 2012 

produces young suckers that are either directly stocked downstream of Davis Dam or are grown 

out at other facilities and stocked elsewhere. 

A-2.3 Ouray NFH 

The Ouray National Fish Hatchery (Randlett Unit) is located on the Ouray National Wildlife 

Refuge about 35 mi southwest of Vernal, Utah. The razorback sucker was first held at the facility 

in 1989 when wild adults were collected from the middle Green River and from the San Juan 

arm of Lake Powell. The Green River fish were used to develop a captive broodstock, and the 

San Juan arm fish were later transferred to the Grand Valley Endangered Fish Facility near 

Grand Junction, Colorado. From 1989 to 1991, three lots of future broodstock (one annually) 

were created using a mixed stock of 15 females and 13 males of Green River origin. From 1993 

to 2001, 25 unique family lots were created using predominantly the Green River stock. Two of 

the lots created in 2001 are from Fl parents of the San Juan and Colorado River arms of Lake 

Powell after the fish were transferred back from the Grand Valley Endangered Fish Facility 

(Bingham et al. 2010). 

The Ouray NFH brood stock was established on the premise that fish surviving in the Green 

River possessed unique survival characteristics worth preserving (Williamson and Wydoski 

1994). Altogether, Ouray NFH holds about 660 adults from the Green, Colorado, and San Juan 

rivers and produces fish for release into the Gunnison, Colorado, and middle and lower Green 

River. It currently maintains a broodstock of about 500 genetically sound Green River razorback 

suckers (25 lots) and continues to rear about 23,000 young to meet stocking goals for 2011. 

These fish are used for floodplain wetland studies and hatchery production for population 

augmentation. The production goal is to rear 14,895 subadults that are 300+ mm total length 

(TL) for release in the middle and lower Green River in Utah.

A-2.4 Grand Valley Endangered Fish Facility 

The Grand Valley Endangered Fish Facility (EFF) is part of the Grand Valley Unit of the Ouray 

NFH (the Randlett Unit is the other). Captive rearing of endangered fish for the Upper Colorado 

River Basin began in the Grand Valley in 1992 with establishment of the Horsethief Rearing 

Ponds, where about 350 adult razorback suckers are currently held as broodstock (Bingham et al. 

2010). Additional propagation facilities were established in 1996 when the 24-Road Hatchery 

was constructed by modifying an existing warehouse near Grand Junction, Colorado. The 

hatchery was expanded in the winter of 1998–1999, and now houses two separate water re-use 

systems. In addition to the hatchery expansion, numerous ponds have been acquired and are used 

to grow razorback suckers for stocking into the Colorado, Gunnison, and San Juan rivers. 

Razorback suckers produced at the Grand Valley EFF are: (a) held on-site until large enough to 

stock (>200 mm TL); or (b) held for 1 year then stocked in grow-out ponds until large enough to 

stock (>200 mm TL). Most of these fish are released into the Upper Colorado and Gunnison 

rivers. 

The construction of 22 grow-out ponds at the Horsethief Canyon Native Fish Facility is proposed 

to begin in 2011 with ponds becoming operational in 2012. These ponds will replace leased 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

ponds in the Grand Valley and will improve the efficiency of raising the numbers and sizes of 

razorback suckers needed to meet stocking targets for the Upper Colorado River and San Juan 

River recovery programs. 

A-2.5 Wahweap State Fish Hatchery 

The Wahweap State Fish Hatchery (SFH) was established in 1993 at Big Water, Utah, near the 

Wahweap Marina on Lake Powell. The facility is administered by the Utah Division of Wildlife 

Resources and raises primarily bonytail for stocking in the Upper Colorado River Basin. The 

Wahweap SFH also maintains the Upper Basin’s backup broodstock for razorback sucker, which 

is 418 fish that average 471 mm TL. 

The goal of the Wahweap SFH is to operate a genetically sound propagation program for high 

priority endangered fish species for the Upper Colorado River Endangered Fish Recovery 

Program (Olsen 2010). The facility operates and maintains propagation facilities that are needed 

to hold, rear, or produce captive-reared endangered fishes for the upper basin in accordance with 

an Annual Propagation Facilities Operation Plan. 

A-2.6 Mumma Native Aquatic Species Restoration Facility 

The J.W. Mumma Native Aquatic Species Restoration Facility (NASRF) was built in 2000 near 

the city of Alamosa, Colorado. It is administered by the Colorado Parks and Wildlife, and is the 

primary hatchery facility for threatened and endangered aquatic species for the State of 

Colorado. This facility has raised bonytail and razorback sucker transferred from other facilities, 

and is currently raising bonytail to meet state and federal stocking requirements in the Green and 

Colorado rivers. Depending on existing demands and space, the Mumma NASRF could hold and 

raise razorback suckers (Schnoor and Marrinan 2009). 

A-2.7 Uvalde National Fish Hatchery 

The Uvalde National Fish Hatchery is a warmwater fish production station located in central 

Texas. Razorback sucker larvae are received from Dexter NFHTC, raised to ~ 300 mm TL 

(average size usually exceeds 325 mm TL each year), and stocked into the San Juan River (Furr 

and Davis 2009). In 2010, Uvalde NFH stocked 4,021 razorback suckers from the 2006 year 

class in the San Juan River, including 2,000 below Shiprock Bridge (mean, 455 mm TL; range, 

333-560 mm TL) and 2,021 below the Animas River confluence (mean, 438 mm TL; range, 318-

545 mm TL). 

A-2.8 Native Fish Work Group 

The Native Fish Work Group (NFWG) of the Lower Colorado River Basin began activities on 

Lake Mohave in 1989 as a multi-agency work group for the purpose of preventing the 

disappearance of the razorback sucker from the reservoir by replacing the old relic population 

with young adults (Mueller 1995, 2006). The NFWG is composed of biologists and resource 

managers from seven federal and state agencies including the Arizona Game and Fish 

Department, Arizona State University, Bureau of Reclamation, Biological Resources Discipline 

Strategy for Establishing the Razorback Sucker Final Report 

A-8 
Appendix A: Culture and Augmentation October 1, 2012 

of the U.S. Geological Survey, National Park Service, Nevada Division of Wildlife, and the U.S. 

Fish and Wildlife Service. 

The population in Lake Mohave declined by about 60%; from 59,500 in 1988 to 23,300 in 1992 

(Mueller 2006). Efforts to have wild fish spawn in isolated backwaters gradually evolved to 

collecting wild larvae from the reservoir and raising them to a size large enough to ensure 

survival in the presence of a suite of predators in the reservoir. From about 1995 to 2005, more 

than 500,000 larvae were collected and transferred to Willow Beach NFH for initial rearing 

(Tom Burke, Bureau of Reclamation [BOR], personal communication, 2004; cited in Mueller 

2006). Some fish were reared on-site; others were moved to other locations for further grow-out, 

including: Bubbling Ponds, Arizona; Niland, California; golf course ponds in Page, Arizona and 

Boulder City, Nevada; Parker, Arizona; and Lake Mohave backwaters (Mueller 1995). 

A-2.9 Navajo Agricultural Products Industry (NAPI) Ponds 

The NAPI ponds are grow-out ponds for razorback sucker that were part of the Biological 

Assessment and Biological Opinion of the USFWS and the Bureau of Indian Affairs that allowed 

the construction of Blocks 9-11 of the Navajo Indian Irrigation Project (NIIP). The Section 7 

consultation on the NIIP for Blocks 1 through 8 was finalized in October 1991. Three grow-out 

ponds were designated to be stocked annually with 3,000-3,500 (> 200 mm TL) hatchery-reared 

razorback suckers produced at Dexter NFHTC using a single cohort strategy; i.e., PIT-tagged 

and stocked in the San Juan River at 300 mm TL after 8 months in captivity. 

The San Juan River Long Range Plan (SJRIP 2009) identifies the need to assess the feasibility 

and implementation of razorback sucker augmentation in the San Juan River. The revised 

augmentation plan (Ryden 2005) and stocking plan and protocols for the NAPI ponds (Furr and 

Davis 2009) provides the necessary guidance for those efforts to fulfill the augmentation needs 

of the Long Range Plan. 

A-3.0 Propagation and Grow-Out Approaches 

The decline of the razorback sucker throughout the Colorado River System by the 1960s raised 

concern over the losses of populations and genetic diversity for the species (Minckley et al. 

1991). In response to this concern, artificially propagated fish were used to augment declining 

stocks. Development of culture techniques began in 1974 with the transfer of 40 wild adults from

Lake Mohave to the Willow Beach NFH (Toney 1974). Wild fish were also taken to Dexter NFH 

where the technology for propagating and raising this species in captivity developed and began 

to evolve (e.g., Inslee 1981; Jensen 1983; Hamman 1985, 1987). 

Initial efforts to raise razorback suckers focused on culture techniques, but it soon became

apparent that all aspects of raising and releasing fish were important. Eventually two approaches 

became apparent: a “broodstock development approach” that produced fish in hatchery settings 

for release of large numbers of young into the wild; and a “repatriation approach” where wild 

larvae were captured and raised in protected ponds before releasing the fish at large sizes to 

avoid predation. These fundamental approaches have been varied and refined extensively to 

identify the best strategy for enhancing genetic diversity and survival of fish in the wild. A third 

Strategy for Establishing the Razorback Sucker Final Report 

A-9 
Appendix A: Culture and Augmentation October 1, 2012 

approach—the “translocation approach”—has recently been implemented and evaluated with the 

Lake Mead population, where mature wild fish are telemetry tags (i.e., acoustic, sonic, or radio) 

and translocated to suitable habitat to help locate wild fish and in anticipation of imprinting by 

their progeny. The following describes these fundamental approaches used to propagate and 

grow-out razorback suckers. 

A-3.1 Broodstock Development Approach 

A-3.1.1 CULTURE OF EGGS AND YOUNG

When wild razorback suckers were first taken to Willow Beach NFH in 1974 (Toney 1974), 

efforts focused on developing culture techniques to successfully procure and fertilize eggs and 

hatch the young (Inslee 1981; Jensen 1983). It was quickly discovered that sexual maturation of 

the razorback sucker was more a function of size than age. Hatchery-reared males matured as 

early as 2 years of age and 355 mm in length while females first produced viable eggs at 3 years 

of age and about 400 mm in length (Jensen 1983). Females typically became gravid at about 

10°C and were ready to spawn at water temperatures of about 12.8°C. Initial culture techniques 

allowed the females to mature with temperature and they were injected with human chorionic 

gonadotropin (HCG), and later with carp pituitary extraction, to finalize maturation of the egg 

mass and to stimulate ovulation. The eggs were incubated in Heath incubator trays at an 

optimum temperature of about 21°C. Hatching occurred in 96 to 144 hours with a peak at about 

120 hours. The newly-hatched larvae are about 15 mm long. 

Once the culture techniques were developed and refined for the razorback sucker, plans were 

developed for Genetics Management Guidelines (Williamson and Wydoski 1994), a Coordinated

Hatchery Facility Plan (Wydoski 1994a), and a Genetics Management Plan (Wydoski 1994b). 

These plans describe the strategies for protecting unique genetic characteristics through planned 

matings of captured wild fish for broodstock development. Broodstock development is the 

traditional method for producing large numbers of fish while preserving the genetic diversity of 

the wild population. As many wild fish as possible are collected and selectively crossed to 

produce known family lots or pedigrees such that future paired matings avoid crossing siblings 

or half-siblings. Continued crosses of unrelated fish and infusion of new wild fish lead to the 

development of a broodstock of genetically diverse adults. Most broodstocks for the razorback 

sucker number at least 300 adults. Selected individuals from each broodstock are crossed 

annually to produce the young needed for release to the wild. Cryopreservation techniques have 

been developed for the razorback sucker to preserve genetic diversity in case of projected losses 

of certain stocks (Tiersch et al. 1997, 2000). 

The recommended breeding strategy for broodstock development for the razorback sucker has 

been to mate 25 females with 25 males (25 x 25 paired matings) to produce 25 pedigreed family 

lots (groups of fish unrelated as siblings or half-siblings) (Wydoski 1994a). This strategy is used 

if sufficient numbers of wild adults are available and removal of fish from the wild will not 

jeopardize the genetic characteristics of the founder stock. An inbreeding rate of 1% is estimated 

for an effective population size of 50 fish that is acceptable for maintaining the genetic diversity 

of wild fish stocks used as founders. 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

When stocks are low, a minimum breeding strategy involving a 5 x 5 di-allele cross may be used 

to develop a broodstock. A 5 x 5 breeding strategy has an effective population size of 10 fish and 

an estimated inbreeding rate of 5%. In the event that 5 males and 5 females are not available, a 

factorial mating may be used to capture the genetic contribution from all fish of the least 

numerous sex. Additional wild adults should be used to supplement the broodstock developed 

from a 5 x 5 or factorial cross when the fish are available to increase the effective population size 

and reduce the estimated inbreeding rate. 

Because the contemporary distribution of the razorback sucker is fragmented by large mainstem

dams and reservoirs and by habitat destruction, isolated stocks have been identified for the lower 

basin (primarily in Lake Mohave and Lake Mead), the upper basin (the Green and Colorado 

rivers), and the San Juan River. Genetic analyses of fish throughout the system revealed a 

gradient of highest diversity toward the lower basin fish (Dowling et al. 1996a, 1996b, 2005) 

with genetic characteristics distinct to certain groups and worthy of protection and preservation. 

Hence, multiple broodstocks for the razorback sucker have been developed that are derived from

fish of a given origin, and general mixing of stocks has been avoided. Broodstocks for the 

razorback sucker are currently housed at: 

• Dexter NFHTC (for Lake Mohave, San Juan River), 

• Ouray National Fish Hatchery (for Green, Colorado, San Juan rivers), 

• Grand Valley Endangered Fish Facility (for Green, Colorado, San Juan rivers), and 

• Wahweap State Fish Hatchery (for Green River). 

The manner in which these fish are handled and used for culture is guided by contemporary 

genetics management plans (Czapla 1999; Crist and Ryden 2003; Dexter NFHTC 2004). 

A-3.1.2 GROW-OUT OF YOUNG

When razorback suckers were first hatched in captivity, the young were held in small hatchery 

troughs and fed commercial fish diets that included pelletized feeds and dried and live brine 

shrimp. It was soon learned that after hatching and initial feeding in hatchery tanks and 

raceways, the young fish fared better in fertilized outdoor ponds where they could feed on 

natural foods of zooplankton (Jensen 1983; Hamman 1985). It was discovered later that this 

strategy simulated available foods in floodplains used as natural nurseries by the newly-hatched 

fish (Grabowski and Hiebert 1989; Papoulias and Minckley 1990; Mabey and Shiozawa 1993). 

The use of outdoor ponds remains the fundamental strategy for growing and holding razorback 

suckers. Small ponds (0.1-acre and 0.2-acre) are considered optimal for rearing razorback 

suckers in family lots to maintain genetic diversity and to reduce handling stress. Although larger 

ponds can be used to maintain larger marked fish, the use of smaller ponds minimizes stress to 

the fish during handling for segregated spawning. Also, small ponds warm quickly and promote 

higher growth than raceways; whereas, raceways have cooler water temperature because they are 

operated as flow-through systems and they require much more water than ponds. The numbers of 

fish and biomass in these ponds need to be continually monitored to ensure a balanced feeding 

regime, optimize metabolic rate, and to ensure adequate dissolved oxygen and avoid build-up of 

Strategy for Establishing the Razorback Sucker Final Report 

A-11 
Appendix A: Culture and Augmentation October 1, 2012 

unionized ammonia toxicity. The techniques to grow out young razorback suckers continue to be 

refined and evaluated to improve growth and especially subsequent survival in the wild. 

A-3.2 Repatriation Approach 

A repatriation program was initiated in 1990 by a cooperative partnership that became known as 

the Native Fish Work Group (NFWG; see Marsh et al. 2005 for detailed description). This 

program was formed from the concern for declining numbers of wild razorback suckers in the 

lower basin and particularly the Lake Mohave population, where the number of fish was 

historically in the hundreds of thousands, but by 2002 was believed to be only about 3,000 

individuals (Minckley et al. 2003). 

Despite evidence of spawning and larval production, juvenile recruitment was failing largely as a 

result of predation by nonnative fishes (Marsh and Langhorst 1988; Minckley et al. 1991; Marsh 

and Pacey 2005). Some fish in the population were estimated to be older than 40 years 

(McCarthy and Minckley 1987), and although still genetically diverse, there was concern over 

loss of genetic viability in the region of the Colorado River System with the greatest genetic 

diversity for the species (i.e., Lake Mohave; Dowling et al. 1996a, 1996b). 

The repatriation approach was based on prior research that showed low survival of stocked 

razorback suckers raised in the more traditional hatchery environments. Based in part on the 

work of Marsh and Brooks (1989), the initial target size for released fish was 250–300 mm TL, 

which required substantial quantities and reliable sources of larvae and predator-free rearing 

environments. In the traditional sense, broodstocks were developed and maintained at hatcheries 

from which eggs were taken and the larvae raised in raceways, troughs, and ponds. This required 

a large amount of hatchery space and high cost to feed and raise the fish to the target size, which 

took up to 2 years. 

As an alternative to traditional hatchery methods, options were explored to rear larvae in seminatural environments such as lakeside backwaters or offsite ponds where early efforts continued 

to have little success. Initially, 200 wild adult razorback suckers were taken from Lake Mohave 

in 1991 and stocked into lakeside backwaters, stripped of gametes, and the young released into 

these backwaters. This effort produced about 200,000 embryos that were released into a lakeside 

backwater but resulted in only 17 juveniles surviving (Minckley et al. 1991; Mueller 1995). 

It was felt that the problem was selective breeding of adults, and in 1994, an alternative effort 

began with collection of wild naturally-produced larvae from inlets and bays around Lake 

Mohave (Mueller et al. 1993). This effort yielded more than 440,000 larvae between 1990 and 

2002 that were subsequently reared in protected lakeside backwaters and offsite grow-out 

facilities free of nonnative predators. These fish were reared to a nominal target size and nearly 

58,000 were released as marked juveniles into Lake Mohave between 1993 and 2002. 

Annual estimates of these “repatriated fish” (i.e., fish derived from wild stock, reared in 

captivity, and stocked into the reservoir) ranged from 1,017 to 2,494 individuals and poststocking survivorship ranged from 2% to 6% for the period 1999–2002 (Marsh et al. 2005). Total 

length at release was the most important determinant of post-stocking survival, which more than 

Strategy for Establishing the Razorback Sucker Final Report 

A-12 
Appendix A: Culture and Augmentation October 1, 2012 

doubled for releases averaging 350 mm TL compared with those averaging 300 mm TL (see 

section 2.5.1 for a further description of survival). 

The goal of the NFWG was to establish a repatriated population of 50,000 razorback suckers that 

adequately represented the known historical genetic characteristics of the wild Lake Mohave 

population. The goal of a “genetic refuge” in Lake Mohave was adopted as part of the 

demographic criteria for the species recovery goals (USFWS 2002). 

A-3.3 Translocation Approach 

Biologists in Lake Mead have had recent success catching wild razorback sucker larvae, raising 

them in captivity, and returning them to the wild as large subadults or adults (Kegerries et al. 

2009; Albrecht et al. 2010). A size of ≥ 500 mm TL is recommended and the fish are equipped 

with telemetry tags to ensure that they can be tracked. Under this approach, telemetered adults 

are released just prior to spawning so they aggregate with, and show biologists the locations of, 

additional fish. Progeny produced by these fish are likely to imprint on these areas. This 

approach of locating existing wild fish with subsequent imprinting of progeny has not been fully 

evaluated, but shows promise from high survival rates and mixing of translocated fish with 

spawning aggregations of wild fish. 

A-4.0 Transport and Release Methods 

A number of methods have been used to transport razorback suckers from grow-out facilities and 

release them into the wild. The initial transport method was the traditional approach of hauling 

fish in aerated tanks on hatchery trucks. Some fish are still transported in this manner, especially 

from the primary culture facilities. Increasingly there has been a trend toward raising fish in local 

riverside or lakeside ponds where transport distances are reduced, stress to the fish is minimized, 

and overall survival is increased. 

A-4.1 Direct Release 

Traditionally and historically, fish transported to a release site were simply released with perhaps 

only attempts to adjust the temperature of the water in the holding tank to the approximate 

temperature of the receiving water. Small razorback suckers that have been released directly into 

receiving waters have experienced low survival, although all factors affecting survival of stocked 

fish are not fully understood. Larger fish have survived better, but a “fright response” has been 

identified in fish released into a new and different environment where foreign chemical cues may 

cause individuals to become frightened and swim great distances in an attempt to locate a more 

familiar area. Direct release of fish may be effective in confined habitats, but may result in initial 

long-distance movement of the fish away from targeted restoration areas. 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

A-4.2 Acclimation 

The post-stocking dispersal, habitat use, and behavioral acclimation of young razorback suckers 

in reservoirs (Mueller and Marsh 1998; Mueller and Burke 2005) show a tendency for recently 

stocked fish to move considerable distances from release sites and the need to acclimate the fish. 

Holding the fish in cages for a short time before release appears to minimize a “fright response” 

and reduces the dispersal of these fish following release. Currently, the SJRIP is experimenting 

with short-term acclimation (i.e., < 48 hours) to reduce dispersal and short-term mortality. 

The prospect of using imprinting by razorback suckers as a strategy for coaxing fish to return to 

certain areas was explored in the late 1980’s. Thyroxine concentrations and chemical imprinting 

of razorback suckers at Dexter NFHTC showed that the species will imprint at the larval stage on 

chemicals including morpholine (Scholz et al. 1993). Further tests on chemical imprinting have 

not been performed on the species. 

A-5.0 History of Razorback Suckers Released 

A-5.1 Lower Colorado River Basin 

Razorback suckers have been stocked in the Lower Colorado River Basin since 1980 and in the 

Upper Colorado River Basin since 1995. Altogether, about 14.3 million razorback suckers were 

stocked in the lower basin from 1980 through 2004 (Table A-2). The numbers of fish stocked per 

year quickly exceeded a million fish, and from 1982 to 1988, nearly 13.9 million fish were 

stocked at a rate of 560,232 to 3,183,235 fish per year. Stocking of razorback suckers in the 

lower basin became more widespread starting in the late 1990s, with the requirement to stock 

25,000 young fish into Lake Havasu and 50,000 into Lake Mohave for a 5-year period to meet 

the conditions of a 1997 USFWS Biological Opinion on Lower Colorado River operations and 

maintenance (USFWS 1997). 

From 1982 to 1988, a period when the largest numbers of razorback suckers were stocked in the 

lower basin, the average size of fish stocked was 16 to 30 mm TL (Figure A-3). These fish were 

mostly recently-hatched larvae and post-larvae that were a few days to a few weeks old. Starting 

in 1989, the average size of razorback suckers stocked began to increase and remained greater 

than 100 mm TL, except for the fish stocked in 1992 and 1996, which averaged about 80 mm

TL. Also starting in 1989, the numbers stocked per year dropped below 100,000 fish. From 1997 

to 2004, the average size of razorback suckers stocked exceeded 280 mm TL and was as great as 

342 mm TL in 2004 when 25,679 fish were stocked. 

Strategy for Establishing the Razorback Sucker Final Report 

A-14 
Appendix A: Culture and Augmentation October 1, 2012 

Table A-2. Numbers of razorback suckers stocked annually into the Lower Colorado River Basin (1980-

2004), mean total length (TL), and estimated number of first-year survivors. Table adopted from Schooley 

and Marsh (2007). 

Year

Lake 

Mead

Lake 

Mohave 

Lake 

Havasu

Lower 

River

Central Arizona 

Waters 

Sum 

All Sites

Mean 

TL (mm)

Survivors

(%) 

1980 79 79 334 20.25 

1981 7,000 7,000 81 0.09 

1982 612,627 612,627 18 0.02 

1983 457 2,664,296 2,664,753 16 0.02 

1984 3, 183,235 3,183,235 16 0.02 

1985 57 3,026,687 3,026,744 18 0.02 

1986 466,923 1,045,271 718,531 2,230,725 30 0.04

1987 1,276,367 334,018 1,610,385 28 0.04 

1988 1,700 558,532 560,232 30 0.09 

1989 1,375 79,680 81,055 103 1.02

1990 3,039 7,228 10,267 242 6.46 

1991 3,968 3,968 197 1.81 

1992 10,899 207 11,106 84 0.74

1993 1,358 1,949 14,006 1,120 18,433 141 5.55 

1994 2,195 6 81 3,493 5,775 320 26.3 

1995 40 1,501 9,888 13,514 3,156 28,099 129 2.17 

1996 3,094 91 70,165 5,963 79,313) 81 1.43 

1997 6 7,317 986 2,000 1,641 11,950 283 10.57 

1998 11 7,667 9,332 62 2,391 19,463 321 16.91 

1999 39 20,166 6,358 2,421 2,000 30,984 294 10.97 

2000 7,215 4,634 4,380 2,131 18,360 310 14.47 

2001 9 15,392 6,784 4,425 1,574 28,184 318 15.41 

2002 23 11,747 30 15,548 2,022 29,370 299 11.22 

2003 12 19,638 142 14,070 378 34,240 313 14.22 

2004 6 13,479 9,869 2,325 25,679 342 23.58 

All years 146 121,668 507,123 2,478,886 11,224,203 14,332,026 0.27

dTL 444 286 32 27 23 26

Survival (%) 65.07 12.53 1.38 0.28 0.09 0.27

Strategy for Establishing the Razorback Sucker Final Report 

A-15 
Appendix A: Culture and Augmentation October 1, 2012 

Lower Colorado River

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

1980198119821983198419851986198719881989199019911992199319941995199619971998199920002001200220032004

N

u

m

ber of Fish Stocked

0

50

100

150

200

250

300

350

400

Total Length (

m

m)

No. Stocked

Mean TL

Figure A-2. Total numbers and mean total lengths (shown above bars) of razorback suckers stocked in the 

Lower Colorado River Basin, 1980-2004. See Table 2 for details on numbers and fish lengths. 

A-5.2 Upper Colorado River Basin 

From 1995 to 2010, nearly 280,000 razorback suckers of various sizes were stocked into the 

Colorado, Gunnison, and Green rivers of the Upper Colorado River Basin (Table A-3; Figure A4). From 1995 to 2001, a total of 49,108 fish were stocked under an Experimental Stocking Plan 

(Burdick et al. 1995). In 2002, 11,648 fish were stocked under the State Stocking Plans for 

Colorado (Nesler 2001) and Utah (Hudson 2001); and from 2003 to 2010, 218,409 fish were 

stocked under an Integrated Stocking Plan (Nesler et al. 2003). These stocking plans identify the 

numbers of razorback suckers that should be produced in hatchery facilities to meet stocking 

numbers that are believed to lead to species recovery. The majority of these fish were raised in 

captivity with the methods and techniques described in section 2.2.1 under a broodstock 

development approach. Of 279,165 fish stocked, a total of 2,277 were recaptured as of 2008. 

Section 2.5.2 describes survival rates of select stocks of these fish. 

In addition to the fish stocked in the Colorado, Gunnison, and Green rivers, a total of 58,916 

razorback suckers were stocked in the San Juan River during 1994-2008 (Table A-4, Figure A5). Average sizes of these fish varied from 192 mm TL to 424 mm TL. The full range of sizes 

stocked was 68 mm TL to 573 mm TL. Unlike the lower basin, there was no distinct pattern in 

sizes of razorback suckers stocked, although a greater proportion of large fish is generally being 

stocked in all rivers of the upper basin. 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

Table A-3. Numbers of razorback suckers stocked annually into the Colorado, Gunnison, and Green rivers 

(1995–2010) and numbers recaptured. Source: Upper Colorado River Endangered Fish Recovery Program. 

Recaptures 

Year Stocking Goal Colorado, 

Gunnison 

Middle 

Green 

Lower 

Green 

Sum All 

Sites Colorado, 

Gunnison 

Green 

1995 13,1001 316 -- -- 316 -- -- 

1996 13,1001 1,112 -- -- 1,112 -- --

1997 13,1001 2,926 -- -- 2,926 0 3

1998 26,2001 606 387 -- 993 1 0

1999 58,6001 6,155 1,357 -- 7,512 0 31

2000 104,8001 29,826 224 -- 30,050 24 10 

2001 104,8001 6,199 -- -- 6,199 31 41

2002 34,9402 11,374 -- 274 11,648 3 20

2003 3,310 & 9,9303 5,541 8,446 2,377 16,364 157 13

2004 3,310 & 9,9303 6,153 9,619 5,957 21,729 121 32

2005 3,310 & 9,9303 10,284 4,850 4,231 19,365 361 101 

2006 3,310 & 9,9303 10,726 5,021 15,188 30,935 15 412

2007 3,310 & 9,9303 10,064 7,749 8,549 26,362 32 225

2008 3,310 & 9,9303 12,949 11,677 10,161 34,787 314 330

2009 3,310 & 9,9303 17,975 14,983 5,017 37,975 -- --

2010 3,310 & 9,9303 9,926 10,926 10,040 30,892 -- -- 

Totals: 142,132 75,239 61,794 279,165 1,059 1,218

1Experimental Stocking Plan (Burdick et al. 1995); fish stocked in various size ranges 

2State Stocking Plans for Colorado (Nesler 2001) and Utah (Hudson 2001) 

3Integrated Stocking Plan: 3,310 in each of 3 reaches in Colorado and Gunnison rivers; 9,930 in each the middle and lower 

Green River (Nesler et al. 2003) 

Upper Colorado River Basin

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

1995199619971998199920002001200220032004200520062007200820092010

Num

ber of Fish Stocked

Colorado, Gunnison

Middle Green

Lower Green

Figure A-3. Total numbers of razorback suckers stocked in the Upper Colorado River Basin, 1995-2010. See 

Table 3 for details on numbers. 

Strategy for Establishing the Razorback Sucker Final Report 

A-17 
Appendix A: Culture and Augmentation October 1, 2012 

Table A-4. Numbers and sizes of razorback suckers stocked annually into the San Juan River (1994-2008). 

Table from Furr and Davis (2009). 

Year # Stocked Mean TL (mm) Range TL (mm) 

19941 688 251 100-446

19951 16 424 397-482

19961 238 336 204-434

19972 2,883 192 104-412

19982 1,275 250 185-470

1999 0 -- --

20002 1,044 214 111-523

20012 688 410 288-560

20023 140 319 110-470

20033 887 327 100-495

20043 2,988 353 225-559

20053 1,996 355 223-534

20063 18,793 265 68-537

20073 22,836 268 110-573

20083 4,444 297 225-390

Totals: 58,916 304 68-573 

1Experimental Stocking Plan: 1994-96 (Ryden and Pfeifer 1994) 

2Five Year Augmentation Plan: 1997-2001 (Ryden 1997) 

3Augmentation Plan: 2002-2008 (Ryden 2003, 2005) 

San Juan River

0

5,000

10,000

15,000

20,000

25,000

199419951996199719981999200020012002200320042005200620072008

N

u

m

b

er of Fi

s

h Stoc

k

e

d

0

50

100

150

200

250

300

350

400

450

Total Lengt

h (

m

m)

No. Stocked

Mean TL

Figure A-4. Total numbers and mean total lengths of razorback suckers stocked in the San Juan River, 1994-

2008. See Table 4 for numbers and fish lengths. 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

A-6.0 Survival of Razorback Suckers Released 

A-6.1 Lower Colorado River Basin 

The survival of razorback suckers released into the wild has not been evaluated until recently. 

For years, large numbers of fish were stocked and it was presumed that at least some proportion 

would survive to justify the effort. However, the numbers of recaptured fish remained low and it 

became evident that strategies were needed for evaluating survival of stocked fish. 

In one of the most extensive survival assessments of stocked razorback suckers in the lower 

basin, Schooley and Marsh (2007) estimated that first-year survival of fish less than 100 mm TL 

was less than 1% (Table A-2). For fish stocked at mean total lengths greater than 100 mm, firstyear survival was as high as 24%. Regardless of release size, estimated annual survivorship was 

less than 30%, although there was a clear relationship between survival and size at stocking 

(Figure A-6). Evidence of long-term survival was rare, indicating that population augmentation 

through stocking failed to replace lost wild populations or establish new ones of significant size. 

Continued stocking to the lower basin was not recommended because threats were substantial 

and conditions were not conducive to long-term survival of stocked fish. Instead, starting in 

about 1997, population augmentation was recommended for “repatriated habitats” (see section 

2.2.2) that were depleted or devoid of predators. However, even predator-free habitats did not 

mitigate avian predation, and appropriate control measures were also advocated for piscivorous 

birds. Primary mortality factors for these stocked fish were attributed to piscine (fish) and avian 

(bird) predators. Piscine predation was ubiquitous in all stocked sites, and predation was 

sufficient to impact stocked populations throughout even when predator abundance was low 

(Schooley and Marsh 2007). 

First-Year Survival of Razorback Suckers Stocked in

the Lower Colorado River Basin

0.0

0.2

0.4

0.6

0.8

1.0

0 100 200 300 400 500 600

Mean Total Length

First-Year S

urvival

0.101

0.261

0.510

0.890

Figure A-5. First-year survival curve as a function of total length at release for repatriated razorback suckers 

that were recaptured as adults during annual March censuses in Lake Mohave, Arizona-Nevada, 1992-2002. 

Survival is shown for lengths of 300, 350, 400, and 500 mm TL. Figure reproduced from Marsh et al. (2005). 

Strategy for Establishing the Razorback Sucker Final Report 

A-19 
Appendix A: Culture and Augmentation October 1, 2012 

A-6.2 Upper Colorado River Basin 

A study of survival of several size classes of stocked razorback suckers (Burdick 2003) showed 

that of nearly 50,000 fish stocked in 1994–2000, only 84 (0.2%) were recaptured after being at 

large ≥ 6 months after stocking. An overview of the stocking program (Francis and McAda 

2006) summarized stocking and capture records throughout the basin from 1995–2005 and 

reported similar low survival rates for stocked fish. An integrated stocking plan (Nesler et al. 

2003) was developed for the Upper Colorado River Basin as guidance for hatchery production of 

fish and releases to the wild. Variations and combinations that involve the use of ponds and 

hatchery tanks were implemented to maximize survival of stocked fish in the wild. 

An analysis of hatchery-reared razorback suckers stocked from 1995–2005 in the Green and 

Colorado River subbasins (Zelasko 2009; Zelasko et al. 2010) found that survival in the first year 

was considerably lower than rates assumed in the integrated stocking plan: 0.05 actual survival 

(mean TL = 252.5 mm, averaging across season of stocking) vs. 0.50 assumed survival (for a 

similar sized age-2 fish). First-interval survival was positively related to total length at time of

stocking, but razorback suckers of nearly all lengths survived at significantly lower rates when 

stocked during summer compared to any other season. After their first interval in the river, 

hatchery-reared razorback suckers survived at a rate similar to the adult rate assumed in the 

integrated stocking plan (i.e., 0.75 vs. 0.70). 

In an attempt to experimentally control potential factors that might affect survival, fish were 

raised at the Grand Valley EFF and the Ouray NFH and subsequent survival was evaluated with 

three basic methods during 2004–2007 (Zelasko et al. 2011). To begin the experiment, fish were 

raised in the hatchery from incubation (April to May) until grading (May to August), at which 

time the fish were graded by size. The smallest fish were moved to outdoor rearing ponds until 

release (August to October of the following year). The ponds varied in size (surface acreage and 

depth) and consisted of leased or donated gravel pits as well as ponds built for fish culture. The 

gravel pits were used to condition fish to variable water conditions and natural diets, whereas the 

fish culture ponds were more controlled and supplemented with fish food pellets. 

The largest-graded fish remained in the hatchery until the following spring (March to May), 

when most were moved to ponds until release (August to October) and the remainder stayed in 

hatchery tanks until release (July to September). These fish were used to evaluate survival under 

each of the following three methods: 

• Pond Fish: Fish raised under the two pond-rearing methods that spent any amount of 

time (approximately 6 months to 1 year) in outdoor rearing ponds. 

• Tank Fish: Fish that were reared solely in hatchery tanks. 

• Intensive Fish: Fish that upon swim-up were moved as larvae from hatchery tanks to 

outdoor ponds (with both natural food and supplemental pellets), where they remained 

until early autumn. The fish were then harvested and moved inside to hatchery tanks to 

increase over-winter growth, and in spring, they were returned to outdoor ponds, where 

they were PIT-tagged and remained until harvest and release in autumn. 

Strategy for Establishing the Razorback Sucker Final Report 

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Appendix A: Culture and Augmentation October 1, 2012 

The mean first-year survival of these hatchery-reared fish was low for each of the three methods: 

0.03, 0.05, and 0.08 for tank-, pond-, and intensively-reared fish, respectively (Zelasko et al. 

2011). However, survival after their first year in the river was high (0.75–0.94), depending on the 

interval and rearing method. 

Zelasko et al. (2011) also reported that length at stocking and 1st-year survival were positively 

correlated (Figure A-7). Survival of fish (reared by any method) smaller than 200 mm TL 

approached zero but increased to an average of 0.83 for the few fish that were stocked larger than 

500 mm TL. Mean 1st-year survival of fish averaging 301.5 mm TL was 0.09, but increased to 

about 0.40 and higher for fish 400 mm TL. Season of stocking also had an effect on 1st-year 

survival; survival of fish 301.5 mm TL stocked in summer were 0.03, 0.03, and 0.04 for tank-, 

pond-, and intensively-reared fish, respectively. Stocking in spring produced the highest mean 

estimated survival rates of 0.20 and 0.29 for pond- and intensively-reared fish, respectively. 

Figure A-6. Total length (TL)-dependent, 1st-interval (ry1) and subsequent-interval (post-ry1) survival rate 

estimates for razorback suckers reared by three methods and stocked into the Upper Colorado River Basin, 

Utah and Colorado, 2004–2007. Interpolated survival rates are shown for lengths of 300, 350, 400, and 500 

mm TL. Figure reproduced from Zelasko et al. (2011). 

Strategy for Establishing the Razorback Sucker Final Report 

A-21 
Appendix A: 

Strategy fo

Culture and Augmentation October 1, 2012 

r Establishing the Razorback Sucker Final Report 

A-22 

In comparing survival rates of razorback suckers stocked in the lower and upper basins (Figures 

A-6 and A-7), it becomes apparent that the grow-out method, the size of fish at stocking, and the 

season of stocking are the principal drivers of survival. The general relationship of survival for 

the two basins is strikingly similar, as are the survival rates at different fish sizes. Survival rate of 

fish released in the lower basin more than doubled from 0.101 to 0.261 for sizes of 300 mm and 

350 mm TL, respectively. For the various methods used in the upper basin, survival of fish 300 

mm TL was generally less than 0.1, but was more than double (0.18–0.57) for fish 350 mm TL. 

Survival rates of fish released at 400 mm and 500 mm TL in the lower basin were 0.51 and 0.89, 

respectively, while rates of fish raised under intensive care in the upper basin were as high as 

0.78 and 0.98, respectively. This information shows that there is a substantial increase in survival 

of fish stocked at a larger size, especially fish larger than 350 mm TL, and that preferred 

stocking size should be 400 mm to 500+ mm. 

A-7.0 Evaluation of Culture and Augmentation Methods 

A large number of methods and variations have been employed in the propagation, grow-out, and 

release of razorback suckers into the wild (Table A-5). The single greatest measure of success is 

the apparent or measured survival rate of stocked fish for the various methods. The two factors 

that most appear to affect survival in the wild are: (1) grow-out method and (2) size of fish at 

release. In both the lower basin and the upper basin, the most successful grow-out methods are: 

(1) repatriation in which wild larvae are raised in protected, predator-free environments, and (2) 

intensive methods in which fish are raised in tanks and ponds to maximize growth and survival. 

Fish are also being introduced into new areas through a translocation approach in which adults 

are taken from wild populations or refuges and released just prior to spawning with the potential 

benefit of imprinting by produced larvae to the new environment. 

When considering the potential for release of razorback suckers into the lower Grand Canyon, 

the methods described and evaluated in Table 5 become relevant in the following manner (see 

section 3.0 for Recommended Augmentation Strategy): 

1. Release Large Numbers of Young: Large numbers of larvae or young will almost 

certainly have a low survival rate if stocked in the lower Grand Canyon. There are no 

protected predator-free habitats in this area and food resources for young may be limited 

to backwater habitats. The river currents will likely transport most of these fish into Lake 

Mead where there are large numbers of predators. There is also the risk of affecting the 

genetic integrity of the wild Lake Mead population if even small numbers of fish from 

selective breeding were to survive. 

2. Release Moderate Numbers of Juveniles: Juveniles are also likely to have a low 

survival rate in the lower Grand Canyon because of the riverine-like environment and the 

large numbers of predators that otherwise have an advantage over naïve hatchery-reared 

fish. 

3. Release Large Subadults or Adults: Large fish of preferably wild origin are the most 

likely to have the highest survival rate in the lower Grand Canyon, and are the least 

likely to disrupt the genetic integrity of the Lake Mead population.
Appendix A: Culture and Augmentation 

Table A-5. Description and evaluation of propagation, grow-out, and release methods for the razorback sucker. 

Method Description Evaluation

Propagation and Grow-Out

Tanks • Larvae raised in hatchery tanks. 

Larvae raised in hatchery tanks must be fed an argrowth and proper development otherwise realize

Ponds • Larvae hatched indoors and moved to outdoor 

fertilized earthen ponds. 

Larvae raised in ponds are exposed to a naturalizfoods that helps to develop feeding strategies and competition and predation. 

3⁄4 Broodstock Development 

(hatchery broodstockdeveloped from wild fish; Larvae produced fromselective paired matings) 

Intensive (Tanks and Ponds) • Larvae raised in hatchery tanks and moved to

outdoor ponds (with both natural food and supplemental pellets), where they remaineduntil early autumn. 

• Fish harvested and moved inside to hatchery 

tanks to increase over-winter growth. 

• In spring, fish returned to outdoor ponds, PITtagged, harvested and released in autumn. 

These were labeled “intensive” fish. 

This approach has resulted in the highest survival sizes of greater than about 300-350 mm TL. Fish exposed to a naturalized environment with naturafeeding strategies and possibly coping with competaken indoors increase their over-winter growth ansurvival when released in the wild. 

3⁄4 Repatriation (fish derived 

from wild stock, reared incaptivity, and stocked into the reservoir) 

Lakeside Ponds • Wild adults held in lakeside ponds and their 

larvae released back to the reservoir. 

• Wild larvae collected and raised in lakeside 

ponds to 300 mm TL and released in reservoir. 

• Wild larvae collected and raised in lakeside 

ponds to 350 mm TL and released in reservoir. 

Larvae collected from natural reproduction are pregenetic diversity, but have low survival because ononnative fish. The survival and growth of these lawhen raised in protected predator-free environmesusceptible to predation if released less than aboufindings are consistent with survival of upper basin is greater for fish larger than about 350 mm TL. 

3⁄4 Translocation (wild fish

located in new area for imprinting by young) 

No Artificial Holding Areas • Wild fish tagged with telemetry and located in

new area for imprinting by young. 

Strategy for Establishing the Razorback Sucker 

A-23 
Appendix A: 

Strategy fo

Culture and Augmentation 

r Establishing the Razorback Sucker 

A-24 

Method Description Evaluation

Transport and Release

3⁄4 Direct release (fish are 

transported and releaseddirectly on-site)

No Acclimation • Fish are released directly into receiving waters

(except for thermal tempering of transport tank). 

Fish released directly into the wild tend to move loafter release. This may be undesirable if the goal stocked. 

Cages • Fish are held in cages in receiving water to 

minimize “fright response”. 

The “fright response” has been documented for vainto the wild. Holding the fish at the release site in acclimate to the new water and to become calmed transport and release. 

3⁄4 Acclimation (fish are 

handled to minimize longdistance dispersal fromthe release site) 

Chemicals • Larval are exposed to chemicals for imprinting

at an early age, and chemicals are used at release sites to cue the fish. 

Larval razorback sucker have been shown to respimprint) such as morpholine, but only one study hafurther evaluation is needed before chemicals can razorback suckers. 
Appendix A: Culture and Augmentation October 1, 2012 

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