Razorback Sucker Xyrauchen texanus Research and Monitoring in the Colorado River 

Inflow Area of Lake Mead and the Lower Grand Canyon, Arizona and Nevada 

Brandon Albrecht 1

, Ron Kegerries 1, Judith M. Barkstedt 2, W. Howard Brandenberg 2, Adam L. 

Barkalow 2

, Steven Platania 2, Mark McKinstry 3, Brian Healy 4, James Stolberg 5, and Zachary 

Shattuck 1

(

1 BIO-WEST, Inc., 2 American Southwest Ichthyological Researchers, LLC, 3 U.S. Bureau of 

Reclamation, Upper Colorado Region, 4 National Park Service, 5 Lower Colorado River MultiSpecies Conservation Program) 

Based on past studies and recent movements of sonic-tagged Razorback Suckers from Lake 

Mead into the lower Grand Canyon (LGC) section of the Colorado River, questions regarding 

this population have spurred further interest into the presence of wild individuals and their 

relationship between the river and reservoir. For more than 20 years, Razorback Suckers were 

thought to be extirpated within the Grand Canyon. This collaborative and holistic study included 

efforts to continue monitoring Razorback Sucker (all life stages) within the Colorado River 

inflow of Lake Mead (CRI) with the inclusion of sonic telemetry, small-bodied fish community, 

and larval fish community sampling from Lava Falls downstream to Pearce Ferry, in the LGC 

(RM 180-280). The specific objectives outlined for these efforts included; (1) conducting larval 

and small-bodied fish studies to quantitatively assess annual fish reproduction, spawning, and 

nursery areas in the LGC, (2) determining if Razorback Suckers were present in the study area 

and if they associated with habitat found within the LGC through telemetry and opportunistic 

adult sampling, and (3) identifying habitat associations, relative spawning and reproductive 

effort, and population trends of Razorback Sucker in the CRI. Specifically, this paper will 

present findings from the CRI portion of this multi-faceted study, particularly regarding natural 

recruitment observed within this population, with additional results from the LGC, as informed 

from small-bodied fish community sampling and adult Razorback Sucker telemetry efforts. 
Razorback Sucker Research and 

Monitoring in the Colorado River Inflow 

Area of Lake Mead and the Lower Grand 

Canyon, Arizona and Nevada 

Brandon Albrecht 1, Ron Kegerries 1, W. Howard Brandenberg 2, Adam L. Barkalow2, 

Steven P. Platania 2, Mark McKinstry 3, Brian Healy 4, Emily Omana 4, and James 

Stolberg 5

(1 BIO-WEST, Inc.; 2 American Southwest Ichthyological Researchers, LLC; 3 U.S. Bureau of Reclamation; 4 

U.S. National Park Service; 5 Lower Colorado River Multi-Species Conservation Program)
Collaboration is key...

Federal, State, Private, Upper and Lower Colorado Basins
65 miles

Increasing evidence of 

lake-wide

movement of RBS
Colorado River inflow (CRI)

2013

2014

Dynamic!

One year of 

change shown
Methods-Lake

Field

• Sonic telemetry

• Trammel netting

• Larval sampling

Laboratory

• Age determination

• Population 

estimation

• Survival estimation
220

240

260

280

300

320

340

360

380

0

20

40

60

80

100

120

1935193719391941194319451947194919511953195519571959196119631965196719691971197319751977197919811983198519871989199119931995199719992001200320052007200920112013

Month End Lake Elevation (meters above mean sea level)

Total Number Razorback Sucker Aged

Year

Long-Term Monitoring (through 2014) Colorado River Inflow (through 2014) Lake Elevation
To date:

Over 100 wild, sexually immature 

Razorback Sucker collected at Lake 

Mead.

Most recent specimens from the CRI 

and from the Overton Arm
0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Razorback Sucker Hybrid sucker Flannelmouth Sucker

CPUE (# fish/net night)

Species

2010 2011 2012 2013 2014

Netting Catch Rates (CRI)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Las Vegas Bay

Echo Bay

Virgin River/Muddy River Inflow

CRI

Year
Larval Sampling (CRI)

12

13

14

15

16

17

18

19

20

0.0

0.1

0.1

0.2

0.2

0.3

0.3

0.4

11-Feb15-Feb19-Feb23-Feb27-Feb

3-Mar7-Mar

11-Mar15-Mar19-Mar23-Mar27-Mar31-Mar

4-Apr8-Apr

12-Apr16-Apr20-Apr24-Apr28-Apr

2-May6-May

10-May14-May

Mean Water Temperature (Celsius)

Mean Larval RS CPUE (#/light-min)

Date

Larval CPUE Mean Temperature (C)

LOCATION 2007 2008 2009 2010 2011 2012 2013 2014

Colorado River Inflow -- -- -- 0.002 0.007 0.0014 0.000 0.042

Las Vegas Bay 0.39 0.43 0.342 0.093 0.282 0.1791 0.391 0.427

Echo Bay 0.43 0.024 0.021 0.269 1.482 0.2197 0.019 0.090

Virgin River/

Muddy River Inflow 0.001 0.116 0.107 0.011 0.013 0.0036 0.205 0.265

“Active Light Sampling”

N=132
Netting Larval
Movement of 

tagged fish from 

CRI into LGC

Adult captures by 

AZGFD

South Cove

Pearce Ferry Rapid

Columbine Falls

Bat Cave

Quartermaster 

Canyon Salt Creek

Surprise 

Canyon Spencer Creek
Lower Grand Canyon

• Determine RBS presence and habitat use in 

LGC

– Larval and small-bodied fish community sampling 

within the LGC

• Assess reproduction, spawning, habitat use, and 

distribution

– Sonic telemetry, opportunistic adult sampling

• Explore linkages between Lake Mead and LGC

• Continued CRI and LGC- Holistic perspective 
LGC Small-bodied Sampling

• 7 sampling trips per year

– October, March-August 2014

– Lava Falls to Pearce Ferry (RM 179-280)

• Sonic Telemetry

– 9 RBS released near Lava Falls

– SURs deployed every 5 miles

– Active Listening

• Seining

• Generalized Random Tessellation

Stratified (GRTS)
GRTS Sampling Design

• Well established and used by NPS

• Ensures spatially balanced, random sampling 

while reducing sampler bias

• 100 RM reach was divided into 800 m 

segments

• S-Draw selected 40, spatially balanced, 

segments with an additional 10 replacements

• Sampling can occur anywhere within the 

segment

• Repeated sampling in each of the 40 segments 

each trip
LGC Small-Bodied Sampling

• No Razorback Sucker

• 4-native species

• Native dominance 

(P<0.0001)

• Native abundance 

increase Jun.-Aug.

• Native fish present 

throughout

• Native dominance at 

nearly all segments

0.0

0.5

1.0

1.5

2.0

2.5

October March April May June July August

Mean Catch Rate (#/m2)

Sampling Trip

Mean Native Mean Nonnative

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

288.2298.5302.6311.1318.0324.0327.8334.2337.3346.2354.1358.9370.0380.9387.2395.3404.1409.4418.4427.2429.9437.6444.0

Mean Catch Rate (#/m2)

River Kilometer

Mean Native Mean Nonnative
LGC Small-Bodied Sampling

• YOY suckers 

dominated early

• YOY Humpback Chub 

present May-Aug. 

(N=144; 16-97mm)

• HC abundance 

increased throughout 

the summer

• Relatively even 

distribution by Aug.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

October March April May June July August

Mean Catch Rate (#/m2)

Sampling Trip

Mean Native

Humpback Chub

Bluehead Sucker

Flannelmouth Sucker

Speckled Dace

YOY sucker

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

288.2298.5302.6311.1318.0324.0327.8334.2337.3346.2354.1358.9370.0380.9387.2395.3404.1409.4418.4427.2429.9437.6444.0

Mean Catch Rate (#/m2)

RIver Kilometer

October March April May

June July August
Telemetry

• LGC

– SURs installed every 5 RM (180-280)

– 10- Adult Razorback Suckers released April 2013 

(Separation)

– 9-Adult Razorback Sucker implanted and released 

March 2014 (Lava Falls)

• CRI

– Two, wild, adult Razorback Suckers implanted 

2014
Telemetry

• 25 (of 30) fish, 22,100 contacts

– 8 CRI released

– 17 LGC released

• Wild fish CRI to OA

• 2011 CRI fish to ~5 miles below 

Lava Falls—missing for 3+ years!

• Movement to/from lake/canyon 

and within river and likely above 

study reach
Conclusions and 

Considerations...

• Razorback Sucker present at the CRI (5th year) and second immature RBS captured at CRI 

(age-3)

• No Razorback Suckers captured during LGC small-bodied sampling in 2014, but recently 

transformed Age-0 juveniles in Iceberg Canyon

• Telemetry identified movement between river and lake, but likely that movement 

occurring above Lava Falls above our study area

• GRTS sampling yielded similar species composition with higher native catch rates (better 

than opportunistic sampling)

• Capture of other small sucker species lends hope for capturing small, wild Razorback 

Suckers in the future

• Age-0 Humpback Chub fairly common from Lava Falls to Pearce Ferry (entire study 

reach)

• Hypothesize that combination of both habitats cumulatively allow for natural Razorback 

Sucker recruitment—dynamic!
Next Steps...

• 7 trips in 2015

– March-Sept

• Continued telemetry

• Continued small-bodied 

seining

– GRTS

• Opportunistic adult 

sampling

• Opportunities for SURs 

upstream?
Reservoirs and Razorback Sucker recruitment...a 

historical perspective... 

• Razorback Sucker becoming a star 

basin-wide, despite NNF predation.

• Floodplain habitats historically 

were and will continue to be 

important for Razorback Sucker 

recruitment, now working better in 

upper basin.

• Lake Mead and the LGC may be a 

contemporary version of 

recruitment/floodplain habitat for 

this species for the lower basin.

• Consider Lake Powell

• Stay tuned for Howard’s talk 

next...

Baser Bend

Photo 

Credits:

Pat Nelson 

and Rich 

Valdez

Lake Mead 

Colorado 

River Inflow
Thank you!

Questions?
RZ FM HYB sucker BH

New Recap Total New Recap Total New Recap Total New Recap Total

5 12 17 65 35 100 2 1 3 1 0 1

TL=530-643 mm TL=310-535 mm TL=472-549 TL=375 mm

Colorado River Inflow Adult, Larval and Sonic Summary (as of 4/2/2015)

Larval Fishing

Date RZ Larvae Captured

3/23/2015 1

3/24/2015 1

4/1/2015 6

Total 8

Light Trapping

Date RZ Larvae Captured

3/17/2015 1

• Sonic fish continue to be heard in both the lake and the river using both active and 

passive gear.

• Three wild RZ were successfully sonic tagged at the CRI.

• A sonic juvenile fish from EB was contacted at the CRI SUR, demonstrating over 35 miles 

of movement.