Arizona Game and Fi

Department 

system wide monitori

David L. Rogowski Arizona Game and Fish Department, Research Branch, 500West Carefree Highway, Phoenix, Arizona 85086 
Lees F

Lake Mead

http://media.npr.org/assets/img/2015/04/17/107f254056f30e3207a51808a0dd2ed1a0ec70
Goal

• Representative sample of the fish communit

Colorado River from Lees Ferry to Lake Me(distribution and relative abundance) 

– objectives 

• 3 trips: 2 spring/summer, 1 in fall 

– Boat Electrofishing – near shore – Baited hoop nets (new in 2016) 

Photo by George Andrejko, AGFD 
Measurements and Processi

 Water temperature Photo by G, Andrejko  Turbidity (NTU)  Fishes 

 Identification  Length  Weight (nonnatives)  Scan for PIT tags  Tag all fish > 150 mm except Rainbow Trout 

rare nonnatives 
AGFD sample site distributi

(electrofishing) Diamo
Lake Mead elevation

 

Average elevation of 

Lake Mead (ft)

1080 1100 1120 1140 1160 1180 1200 800 900 1000 1100 1200 

1300 

1930 1940 1950 1960 1970 1980 

Average yearly elevation of

Lake Mead (ft) 

Year 

Photo by Ethan Miller / Getty Images

2000 2005 2010 
Humpback Chub – range expansio

lower Grand Canyon or better sam

• What is their distribution? • Is their recent occurrence in the lower/wes

Grand Canyon new? 
Number of Humpback Chub cap

within Colorado River by river m

(1980-2014) Little Colorado River 

confluence 

1000 

Number of HBC captured at specific river mile

(log scale)

(1980- OCT 2014)
 10010

1 

0.00 50.00 100.00 150.00 200.00 250

Colorado River Mile 
What is the distribution of Hum

Chub in the Grand Canyon

• AGFD – representative sample of the R

but not effective (e.g. electrofishing) 

• USFWS – effective sampling (hoop net

trammel nets), but not representative 

Picture by Josh Smith 
-1

123456789

10

0 25 50 75 100 125 150 175 200 225 

Number Humpback Chub/hoopnet

River Mile

2016 Humpback Chub CPUE 

-0.05 

0.05 0.15 0.25 0.35 0.45 0.55 

Humpback Chub

Catch per unit effort (fish/hour) Diamond Cre

hoop nets (n = 319) 

0 50 100 150 200 

River mile 
Spri

RM 

Humpback 1214 n=42

10

8 Chub length 6

Frequency
 frequency 42

0 histograms 84 102 121 139 158 176 195 213 2

Total length (mm) of Hu

Bin (label shows upp

40

Fall sample RM 225-281 n=106 

75 100 125 149 173 197 221 24

353025201510

50

Frequency
 

Humpback Chub total leng

Bin (label shows upper l
Humpback Chub Recaptur

(hoop nets)

• Above RM 220: 21/37 recaptures (57%

– At Little Colorado River confluence ~80% 

recaptures

• Below RM 220: 3/146 recaptures (2%) 

– 3 were tagged recently and at RM 238-239 

Photo by George 
Humpback Chub

• Occur throughout Colorado River? 

– Occurrence below RM 225 (Diamond 

• Not sure if this is new or not? 

– No longer a lake – More turbid, temperatures are warmer – Not adequately sampled 

Photo by George Andrejko, AGFD 

~ RM 264 
 

Flannelmouth Sucker CPUE (fish/h

baited hoop nets (n=319) by river 

Flannelmouth Sucker

catch per unit effort

(fish/hour)
 

2.5 2.0 1.5 1.0 0.5

-0.1

River mile 

0 50 100 150 200 
 

Speckled Dace CPUE via baited 

nets (n=319) for 2016 by river m

0 50 100 150 200 

River mile 

-0.1 

0.2 0.4 0.6 0.8 1.0 1.2 1.4 

Speckled Dace

catch per unit effort

(fish/hour) 
Electrofishing results 

• 2016 spring/summer only 

• 639 sites (*250 m = 182.75 km) • ~18 % of shoreline sampled 

Photo by George Andrejk
2016 AGFD summary resu

Native Electrofishing Hoop nets (106, 132, 81) totals 

N 639 319 

Humpback 

Chub 

Flannelmouth 

Sucker 

Bluehead 

Sucker 

26 

2200 

198 

197 

1120 

3 

223 

3320 

201 

Speckled Dace 

Razorback 

Sucker 

496 

1 

239 

0 

736 

1 
Nonatives Electrofishing Hoop nets totals 

Rainbow Trout 928 2 930 

Brown Trout 77 0 77 

Common Carp 47 4 51 

Fathead 

Minnow 46 7 53 

Striped Bass 5 0 5 

Plains Killifish 2 0 2 

Red Shiner 2 0 2 
2016 CPUE of 60 

50 

fishes by reach 40

30 20 

Native Fish 

FMS BHS SPD 

1. 0 < 56 BHS2. 56 < 803. 80 < 130

CPUE (fish/hour) 

10

0

4 

No

RBT 

BNT 

Carp 

0 1 2 3 4 

4. 130 < 180 3

2 5. 180 < 220 

6. 220 - 281 1

0 

Colorado River Reach 
(fish/hour) by 

electrofishing 

System wide 

CPUE

species and 

year

via 

CPUE (fish/hr) CPUE (fish/hr) CPUE (fish/hr)

A

100

Rainbow trout 

80604020

0

2000 2002 2004 2006 2008 2010 2012 2014 2016

C

8

Common carp

642

0 

2000 2002 2004 2006 2008 2010 2012 2014 2016

E

543210

2000 2002 2004 2006 2008 2010 2012 2014 2016 

Bluehead sucker 

Year 

B

20

Brown trou

1510

50 

2000 2002 200

D

755025

0 

Flannelmou

2000 2002 200

F

3025201510

50

Speckled d

2000 2002 20
A

Reach 1River Mile 0 - 56

400 Rainbow 350

450300200 Trout 250150

50 CPUE via 0

100

2001 2004 2007 2010 2013 2016

C electrofishing 60

4020

0

2001 2004 2007 2010 2013 2016

Reach 3 River Mile 69.1 - 109 

E

12

840

2001 2004 2007 2010 2013 2016

Reach 5 River Mile 179.1 - 225 

Year 

CPUE (fish/hr) CPUE (fish/hr) CPUE (fish/hr)

B

450400350300250200150100

50

0

Reach 2 River Mile 

2001 200

D

604020

0 

Reach 4 River Mile 

2001 20

F

210 

Reach 6 River Mile 

2001 20
48 7810713716619522525428331334237

Frequency
 

Rainbow Trout length frequen

distribution 2016 (via electrofish

80

N = 936 70

605040302010

0

Bin (label shows upper limit)
4 Brown Trout Reach 1 

River Mile 0 - 56 

A

CPUE via 

321 electrofishing 0

2001 2004 2007 2010 2013 2016

C

Reach 3River Mile 69.1 - 109

30402010

0

2001 2004 2007 2010 2013 2016

E

54321

Photo by Mike Roth, Northern 0

2001 2004 2007 2010 2013 2016

Reach 5 River Mile 179.1 - 225 

Arizona Guide Service 

Year 

CPUE (fish/hr) CPUE (fish/hr) CPUE (fish/hr)

B

43210 

Reach River M

2001 200

D

10

Reach 4River Mile 1

86420

2001 20

F

1.00 0.75 0.50 0.25 0.00 

Reach 6 River Mile 

2001 20
Brown Trout length frequency histogr

year (RM 0- 85, 90-281) 

2000 2001 2002 2003 2005 2006 2007 2008 2010 2011 2012 2013 2015 2016 

0.000 0.005 0.010 0.015 

0.000 0.005 0.010 0.015 0.000 0.005 0.010 0.015 0.000 0.005 0.010 0.015 

Density 

0 100 200 300 400 500 600 0 100 200 300 400 500 600

Total length (mm) 
CPUE of fishes 

from the Bright 

Angel reach (RM 

80-90)

via electrofishing 

CPUE (fish/hour) CPUE (fish/hour) CPUE (fish/hour) 

605040302010

0

140120100

80604020

0

353025201510

50

Brown Trout 

2000 2002 2004 2006 2008 2

Rainbow Trout 

2000 2002 2004 2006 2008 2

Flannelmouth Su

2000 2002 2004 2006 2008 2

Year 
6 

0 1 2 3 4 5 BNT-above 

RBT-above 

1998 2000 2002 2004 2006 2008 2010 2

CPUE of trout at 

the Little Colorado 

confluence area 

BNT CPUE (fish/hour) BNT CPUE (fish/hour) 

-1 (above: ≥41.5 < 61.5; below: ≥61.5 ≤81.5) 67

BNT-below RBT-below 

via electrofishing 54

3210

-1

1998 2000 2002 2004 2006 2008 2010 2

Year 
This year - 2017

• Continue hoop nets • Extend sampling below Pearce Ferry Ra

– 3 night hoop net trial 

Pearce Ferry Rapid
Acknowledgements

• AGFD crew: K. Manuell, R. Osterh

L. Winters, & P. Wolters 

• Humphrey Summit & Saint Judes L

boatmen 

• All of the volunteers • Past & present agency personnel 
“Humpback Chub aggregatio

From: Valdez

& Ryel 1995
2016 number of Humpbac

Chub/hoop net (285 hoop ne

-1 

1 2 3 4 5 6 7 8 9 

10

Number Humpback Chub/hoopnet 

Di

0 25 50 75 100 125 150 175 200 225 

River Mile 

182 Hum
4 

3 

Brown 2

1 

Trout 0

4 length 3 2 frequency 1 0 histograms 

(river mile 34 8-60) 12 

0 43210

2000 2001 2002 2003 2005 2006 2007 2008 2010 2011 2012 2013 2015 2016 

One fish captu

~365 mm FL

100200300400500600 100200300400500600 

Total length (mm) 

Density 
Species 

Native 

Electrofishing 

Hoop 

n e 

t 

s 

Percent of 

total 

catc 

h 

Overall 

electrofishing 

CPUE [95% 

CI] 

Overall ho

CPUE 

C

Bluehead Sucker 

Flannelmouth Sucker 

Humpback Chub 

Speckled Dace 

Razorback Sucker 

198 

2,200 

26 

496 

1 

6 

1,120 

179 

239 

0 

3.6 

59 

3.7 

13.1 0.02 

3.44 [2.61, 4.68] 30.2 [26.8, 33.6] 6.28 [4.67, 7.89] 

3.51 [2.950.56 [0.410.75 [0.49

Unidentified Sucker 1 0 0.02 

Flannelmouth-Razorback 

Sucker Hybrid 1 3 0.07 

Sub total 2,923 1,547

Nonnative 0 1 0.02 Black Bullhead