National Park Service

U.S. Department of the Interior

Grand Canyon National Park

Brian Healy, Robert Schelly, Emily Omana Smith, Charles Yackulic, 

Melissa Trammell, Rebecca Koller, Keegan Evans, Mary Conner, 

Mark McKinstry, Kirk Young, Phaedra Budy

Joe Tomelleri Illustrations
Funded by:

Reclamation (non-AMP funds)

National Park Service

Grand Canyon Conservancy

Arthur L. & Elaine V. Johnson Foundation Center for 

Colorado River Studies – Utah State US Geological 

Survey, Utah Cooperative Fish and Wildlife Unit (In 

Kind)

Utah State University-Ecology Center/Watershed 

Sciences National Park Foundation/Albright-Wirth 

Grant
Conservation Measures –

Humpback Chub

• Glen Canyon Dam Operations Biological Opinion:

• Control of nonnative fish (rainbow and brown trout)

• Translocations to Grand Canyon tributaries

• Objective: assess efficacy of conservation measures
1. Summarize results of invasive trout control efforts and

trends in fishes in Bright Angel Creek

2. Preliminary results of generalized linear mixed effects

models to predict native fish distribution and abundance in

Bright Angel Creek

Assess hypothesized relationships among native fishes, and 

invasive trout, temperature, hydrology, and electrofishing 

effort

Results of humpback chub translocations to Havasu and

Bright Angel creeks
Study Area – Bright Angel Creek

Speas 

2003

Bright Angel Creek Inflow
3

4

5

gs Creek Angel Sprin

Creek

1

Roaring Sprin gs 

2
Changes based on peer-review:

• “Continue trout control to avoid

a potential for a compensatory

response, ...redistribute trout

suppression efforts to “hotspots”

..., and/or target areas of high

YOY trout abundance. “

• Two-pass depletion, with

targeted single-pass

electrofishing at “hot spots”
Rainbow trout

• Increase in 2018 

Brown trout

• Strong BNT year class

in 2018

• 2018 BNT abundance

= 84% decline since

2012 (>90% through

2017)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

2012 2013 2014 2015 2016 2017 2018

Abundacne Estimate - 2-pass data

Bright Angel Creek al, young-of-year, adult 

abundance

: tot

RBT

2012 2013 2014 2015 2016 2017 2018

Rainbow trout: total catch- 2-pass

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Sum of 2-pass catch

total >230 YOY
Brown trout: 

• Very few

adult/spawning BNT

remaining

• Shift in size structure

since 2012

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

2012 2013 2014 2015 2016 2017 2018

Abundacne Estimate - 2-pass data

Bright Angel Creek: total, young-of-year, adult 

abundance

total >230 YOY

2018 (red) adults
Brown trout: 

• Very few

adult/spawning BNT

remaining

• Shift in size structure

since 2012

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

2012 2013 2014 2015 2016 2017 2018

Abundacne Estimate - 2-pass data

Bright Angel Creek: total, young-of-year, adult 

abundance

total >230 YOY

2018 (red) adults

Hypothesized vulnerable 

period for YOY trout
Native fishes

• Creek-wide abundance

• Sum of 2-electrofishing

passes (preliminary)

• Declines in catch in

2017-2018

0

100

200

300

400

500

600

2012 2013 2014 2015 2016 2017 2018

Sum of 2-pass catch

Native suckers: total catch -2 passes

FMS BHS

0

5000

10000

15000

20000

25000

30000

2012 2013 2014 2015 2016 2017

Sum of 2-pass catch

Speckled dace: total catch - 2 passes

SPD
Drivers of native fish abundance and distribution

Time

Invasive

Native Native

Invasive

Native fishes ~ f (Invasive fishes, environmental 

variation, electrofishing, time, space)
Drivers of native fish abundance and distribution

Time

Environmental 

Variation

(temp., flooding) (-)

Environmental 

Variation

(temp., flooding) (+)

Invasive

Native Native

Invasive

Native fishes ~ f (Invasive fishes, environmental 

variation, electrofishing, time, space)
Drivers of native fish abundance and distribution

Time

Mechanical Removal

(electrofishing) (-)

Environmental 

Variation

(temp., flooding) (-)

Mechanical Removal

(electrofishing) (~)

Environmental 

Variation

(temp., flooding) (+)

Invasive

Native Native

Invasive
Methods – Data Analysis

• Objective: predict distribution and 

abundance of native fish

• Analytical approach:

• Hypothesized drivers:

• Flow, spatial-thermal, trout, electrofishing effort, 

interactions

• Generalized linear mixed-effects models

• Probability of occurrence of native fish, and 

abundance components 

• Random effects:

• Year – random intercept

• Reach - Random intercept and slope

• Model Evaluation – lowest BIC 
Methods – Data Analysis

“Spatial-thermal” variable:

• Bair et al. (in press)

• Temperature predicted by distance

from source
Methods – Data Analysis

“Spatial-thermal” variable:

• Proxy for temperature

• Assigned sites a “distance from the 

Colorado River”
Flow variables

Water Year 2012 Water Year 2017

• Variation in flow variability

• Captured in flow metrics – Spring and monsoon season 

flow variability/flood magnitude 

• Annual time step (years very different)
• Top Model:

• Native Fish (aggregated) abundance ~

• Spatial-thermal (-)

• Trout density (-)

• Spring flooding index (+)

• Native Fish (aggregated) prob. of

occurrence ~

• Spatial-thermal (-)

• Monsoon flooding index (+)

• Electrofishing not a strong predictor of

native fish counts

Spatial-thermal

Trout Density
• Top Model:

• Native Fish (aggregated) abundance ~

• Spatial-thermal (-)

• Trout density (-)

• Spring flooding index (+)

• Native Fish (aggregated) prob. of

occurrence ~

• Spatial-thermal (-)

• Monsoon flooding index (+)

• Electrofishing not a strong predictor of

native fish counts

Spring Flooding

Monsoon Flooding
• Brown trout abundance remains 84% below baseline levels

• Native fishes have increased and expanded upstream with

declines in trout

• Temperature, trout, and flows predict native fish abundance

• Drought in winter-spring 2018 could explain small native fish

and large trout cohorts

• Effects of reductions in invasive trout likely outweigh any

negative effects of electrofishing to individuals
E X P E R I E N C E Y O U R A M E R I C A

Photo by George Andjreko, AZ Game & Fish

Illustration by Joseph Tomelleri
• Largest Population

• Little Colorado River – Center

of the Humpback Chub

Universe:

• Sole Spawning Location =

Risk of Extirpation

https://www.smithsonianmag.com/arts-culture/who-can-save-the-grand-canyon-180954329/

Hatchery Rearing

• Parasite & disease

treatment

• Flow training

• Pit tagging

• Weight & length measurements
Shinumo ~ 1,102 fish, 2009-2013

Havasu ~ 1,956 fish, 2011-2016

Bright Angel ~ 116 fish, 2018
1) Annual Abundance of Humpback Chub

Compared to the Little Colorado River (sou

2) Apparent Survival

3) Growth

4) Reproduction/Recruitment to Maturity

rce):
~12 meters
• Population estimate ~ 

300

• Non-translocated/fish 

produced in situ catch 

continues to increase

• ~50% of abundance 

estimate in May, 2018
√ Reproduction and Recruitment

• Continued recruitment 

• 2018 – Increases in catch of fish 

produced in Havasu Creek

• Multiple age-classes present 

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Sampling Occasion

No. Non-translocated Captures of 

Humpback Chub
• May, 2018, released 116 adult humpback chub (mean TL =257 mm)

• Detected 29 individual translocated humpback chub (May – February)

• 2 HBC tagged in the Colorado River – RM 80 and 100

• 2 Brown trout tagged at -3 and -4 mile above Lee’s Ferry (90+ miles

upstream)

E X P E R I E N C E Y O U R A M E R I C A
Bright Angel Creek:

• Antenna data and captures (fall hoop-netting + e-fishing)

• Preliminary apparent survival ~80%; estimate will

change with additional data

*BAC - Preliminary estimate

0.7

0.75

0.8

0.85

0.9

0.95

1

Monthly survival 

Cohort or Shinumo Creek time period (time-varying model)

Apparent survival - all translocations

*
• Havasu Creek represents a second

reproducing population in Grand

Canyon

• Next steps: Spring 2019, larval

collection for Bright Angel translocation

#2 (2020)

• Continued monitoring/trout suppression

- Bright Angel

• Monitoring and potential augmentation

- Havasu Creek.
Questions?
Annual Reports (2): translocations and nonnative

Fish Control

Trip reports (all trips)

Manuscripts in preparation:

• Establishment of an endangered humpback chub

population through experimental translocations (to be

submitted to North American Journal of Fisheries

Management)

• Native fish recovery across environmental gradients

following invasive trout control in a Grand Canyon

tributary(to be submitted to Canadian Journal of Fisheries

and Aquatic Sciences)
E X P E R I E N C E Y O U R A M E R I C A
E X P E R I E N C E Y O U R A M E R I C A
• Water years:

2017 and 2018
• Water years:

2017 and 2018

E X P E R I E N C E Y O U R A M E R I C A
• Water years:

2017 and 2018

E X P E R I E N C E Y O U R A M E R I C A

2018