Status and Trends of 

and Nonnative Fishes 

Colorado River

David Rogowski

Lisa Winters

Robin Osterhoudt

Pilar Wolters

Kristy Manuell
Overview 

• Long term monitoring 

– Numbers summary – Humpback chub – Bright Angel Creek (RM 80-90) – Little Colorado River (RM 40-80) 
Glen Can

http://www.usbr.gov/uc/waerial.jpg

Lake Mead

http://media.npr.org/assets/img/2015/04/17/107f254056f30e3207a51808a0dd2ed1a0ec70
AGFD long term monitorin

• Goal – representative sample of the fish com

the Colorado River from Lees Ferry to Lake 

• Methods 

– Random stratified sampling – 3 trips: 2 spring/summer, 1 in fall – Boat Electrofishing – near shore at night 

Photo by George Andrejko, AGFD 

Photo by G. Andrejko 
AGFD Summary

• Sampling (each site = 250 m) 

• 1-16 April = 324 sites • 30 April – 15 May = 334 sites • Fall (12-16 Oct) = 96 sites (turbidity > 4000 

• ~164.5 km shoreline sampled 

• ~18% of total shoreline sampled 

• 4,175 fish captured 

Photo b

y Geor

ge 
Sites sampled in 2015
100 

Riverwide 60

80

CPUE 20

40

0 

Rainbow trout 

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

20 1510

50 

Brown trout 

2000 2002 2004 2006 2008 2010 2012 2014 2016 2000 2002 2004 200

C

8

Common carp 

642

0 

D

755025

0 

Flannelmouth suc

2000 2002 2004 2006 2008 2010 2012 2014 2016 2000 2002 2004 200

0 1 2 3 4 5 

0 5 

10 15 20 25 30 

E F

Bluehead sucker 

CPUE (fish/hr) 

Speckled dace 

2000 2002 2004 2006 2008 2010 2012 2014 2016 2000 2002 2004 200

Year 
Five Year Trends in CPUE

Species F-value df 

Native 

Bluehead Sucker (BHS) 1.22 

Flannelmouth Sucker (FMS) 1.94 

Speckled Dace (SPD) 3.72 

Nonnative 

Brown Trout (BNT) 9.94 

Common Carp (CRP) 4.76 

Rainbow Trout (RBT) 1.60 
Humpback 

chub

• What can long-term SWEF monitoring te

– What is their distribution? – Is their recent occurrence in the lower Grand 

something new? 
AGFD long term monitorin

• Electrofishing nearshore at night 

– Somewhat standardized in 2000 – 2014 – current: random stratified sampling w

included below Diamond Creek (~RM 225) 

– Not particularly effective for HBC – But we catch a few Photo by George Andrejko, A
Humpback Chub number

Number of humpback chub
 

10000

1000

100

10

1

0.1 

Semi-standardized Standardized electrofish

1985 1990 1995 2000 2005 2010 

Year
150

TL

Humpback chub distribution 

AGFD sampling 2000-2015

100 200 300 400 

Total length 

50 100 200 

River mile 
Distribution of HBC

Humpback chub distributio

Total lenght (mm) 200

400300 

0 20 40 60 80 100 120 140 160 180 200 220 240 2

River mile

100 
2015 

2014 2013 2012 2011 2010 2009 2006 2005 2004 2003 2002 2001 2000 

year 2008 

2007 

Sample site distribution

0 20 40 60 80 100 120 140 160 180 200 220 

START_RM 
2009 

2010 2011 2012 2013 2014 2015 

Humpback Chub - distributi

year 2008 

2007 2006 2005 2004 2003 2002 2001 2000 

0 20 40 60 80 100 120 140 160 180 200 220 

START_RM 
Lake Mead elevation

 

Average elevation of 

Lake Mead (ft)

1080 1100 1120 1140 1160 1180 1200

Average yearly elevation of

Lake Mead (ft)
 

1300120011001000

900800

Year 

1930 1940 1950 1960 1970 1980 

2007 began sampling

below RM 225

2000 2005 2010 
Humpback Chub

• Occur throughout Colorado River presen

– Occurrence below RM 225 (Diamond Creek

• Not sure if this is new or not? 

– No longer a lake – Temperatures are warmer – Not adequately sampled 

Photo by George Andrejko, AGFD 

~ RM 264 
Trout and long term monitor

• Tributaries 

– Little Colorado River – Bright Angel Creek 
Little Colorado 6

BNT-above 

5 RBT-above River inflow 43

CPUE (fish/hour) CPUE (fish/hour) • CPUE of trout 20 mi above and below the 210-11998 2000 2002 2004 2006 2008 2010 201

LCR 75 BN

RB

4 3 210 

-1

1998 2000 2002 2004 2006 2008 2010 2012 

Year 

6
Bright Angel Creek 

Inflow (RM 80-90)

• Nonnative trout removal in 

a tributary stream: does it benefit native fish in the mainstem Colorado River? 

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

70605040302010

0

160140120100

80604020

0

25201510

50 

Brown Trout 

2000 2002 2004 2006 2008 

Rainbow Trout 

2000 2002 2004 2006 2008 

Flannelmouth Su

2000 2002 2004 2006 2008 

Year 
Fraction
 

Fish community at RM 80-9

Bright Angel Creek inflow reach 

native nonnative 

1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 

Year
Percent FMS downstream Bright 

Fraction FMS (log10(x))0.00 -0.50 -1.00 -1.50 -2.00 

-2.50 

Creek (RM 90-140)

y = 0.0634x - 128.27 R2 = 0.4503 

1998 2000 2002 2004 2006 2008 2010 2012 

Year
BNT removal and CPUE in 

mainstem

45 35 

BNT-CPUE BNT-removed 

30 2520 15 10 

50 

1999 2004 2009 2014 

Year 

40 

BNT- CPUE (fish/hour)
 
BNT CPUE (Fish/hour) 

Predicting BNT CPUE 

BNT.CPUE = RBT.CPUE + BNT.CPUE-1yr - BNT.removed 

60 50 40 30 20 10 

0 

1999 2001 2003 2005 2007 2009 2011 201

BNT.CPUE Rpredicted.BNT.CPUE 

Year 
Bright Angel Creek trout remova

Colorado River effects

• We can model trout metrics and removal i

important component of those models 

• Fish community changed - Due to removal? • Reduction in BNT CPUE • Length distribution of BNT has increased • Reduction in RBT CPUE 
Summary 

• Representative sample: 18% of the shorel• HBC are throughout the river (RM 0-280) 

– Don’t know if this is new or not? 

• We can detect an effect of the NPS Bright 

trout removal project in the mainstem 
Acknowledgements 

Humphrey Summit & Saint Judes - boatmen All of the volunteers, Past & present agency personnel