U.S. Department of the Interior

U.S. Geological Survey

Drivers of humpback chub population dynamics

Maria Dzul*

Charles B. Yackulic*

Mike Yard*

*US Geological Survey, Southwest Biological Science Center, Grand 

Canyon Monitoring and Research Center

Annual reporting meeting

Flagstaff, AZ, March 2018

U.S. Department of Interior

U.S. Geological Survey
Presentation outline

 1) Two species mark-recapture 

model

 2) Adult humpback chub 

population dynamics in eastern 

Grand Canyon

 3) Humpback chub in western 

Grand Canyon (pilot year)
NORTH

0 

Nev Utah ~ 0 

Study area 

Ariz. z 

s: 

<D 

X 

3£0N 

J o 25 KILOMETERS 

\ 

\/ ---'-,,-----,- I 

0 

I 

I 

20 M.ILES 
Two species mark-recapture model

Yard et al., 2011. Trout Piscivory in 

the Colorado River, Grand Canyon: 

Effects of Turbidity, Temperature, 

and Fish Prey Availability, 

Transactions of the American 

Fisheries Society

Ward et al, 2016. Effects of turbidity 

on predation vulnerability of juvenile 

humpback chub to rainbow trout and 

brown trout. Journal of Fish and 

Wildlife Management, 7(1), 205-212.

Dzul et al, 2016. Incorporating 

temporal heterogeneity in 

environmental conditions into a 

somatic growth model. Canadian 

Journal of Fisheries and Aquatic 

Sciences, 74(3), 316-326.

Covariates:

Turbidity

Temperature

RBT density

HBC density

Responses:

Survival

Growth

P-cap 
Effect on survival:

Turbidity (-)

RBT (-)

pseudo-R2: 0.38

C. B. Yackulic, J. Korman, M.D. Yard, and M. Dzul. 2018. Ecology. 
Effect on growth:

Temperature (+)

Turbidity (+)

RBT (-)

pseudo-R2: 0.43

C. B. Yackulic, J. Korman, M.D. Yard, and M. Dzul. 2018. Ecology. 
Effect on p-cap:

Temperature (+)

RBT (-)

pseudo-R2: 0.59

C. B. Yackulic, J. Korman, M.D. Yard, and M. Dzul. 2018. Ecology. 
RBT negatively affect HBC recruitment in the Colorado River

C. B. Yackulic, J. Korman, M.D. Yard, and M. Dzul. 2018. Ecology. Inferring species 

interactions through joint mark-recapture analysis. 
July abundances of age-0 humpback chub in 

the LCR

Mean N = 

14,061

Preliminary data. Do not cite.

Total abundance (includes fish <40mm TL) 

40 -

---. 

Cl) 30 -

0 

0 

0 

~ 

...__ 

Q) 

u 20 -

C 

ro 

"'O 

C 

::::l 

..c 

<( 10 - I 

I 

I 

I 

0 19697 9866 27847 4658 8239 

2013 2014 2015 2016 2017 
 RBT had negative effects on HBC survival, however, 

magnitude of this effect is still uncertain

 Environmental influences (temperature and turbidity) 

were stronger than RBT effect

 Lots of unexplained variability in survival and growth 

(e.g., food limitation)

 Temperature has a large effect on capture probability

Take-home messages
Presentation outline

 1) Two species mark-recapture 

model

 2) Adult humpback chub 

population dynamics in eastern 

Grand Canyon

 3) Humpback chub in western 

Grand Canyon (pilot year)
Abundance of adult humpback chub 

(≥ 200mm TL) that spawn in the LCR

Preliminary data. Do not cite. Vertical lines represent 95% confidence 

intervals.
Abundance of subadult humpback chub 

(150-199mm TL) in the Little Colorado River (LCR) and in the Colorado River juvenile chub 

monitoring (CR-JCM) reach

Preliminary data. Do not cite. Vertical lines represent 95% confidence 

intervals.
Spawning probabilities of adult humpback chub 

200-249mm TL >250 mm TL

Preliminary data. Do not cite. Vertical lines represent 95% confidence intervals.

C) 

C 

11.0 

0.8 

-~ 0.4 

al 

a. 

U) 

0.2 

0 . 0 

-

-

-

-

-

-

• 2009-20114 

• 2015-20116 

..,. 2017 

... ~ ' 

t + t 

t 

Small adults Lairge adults 
Take-home messages

 The adult humpback chub population in eastern Grand 

Canyon seems to be stable

 Subadult humpback chub numbers are more variable, 

potentially a decrease in numbers in the LCR since 2013 

and an increase in JCM since 2016

 Spawning probabilities decreased from 2015-2016. 

Some evidence that the 2012 age-0 cohort is starting to 

recruit.
Presentation outline

 1) Two species mark-recapture 

model

 2) Adult humpback chub 

population dynamics in eastern 

Grand Canyon

 3) Humpback chub in western 

Grand Canyon (pilot year)
5

10

15

20

25

30

Temperature (C)

| | | | |

Jan-2017 Apr-2017 Jul-2017 Oct-2017 Jan-20

~ RM 61

LCR

~ RM 225

Preliminary data. Do not cite. Water temperatures of the Little Colorado 

River (LCR) and the Colorado River at river mile (RM) 61 and 225..
0

5

10

15

20

25

30

35

40

45

Catch

SIZE CLASS (TL)

HBC JUVENILE 

SIZE DISTRIBUTION

JCM-FALL CYN. & JCM-LCR

FAL-Oct17

PAR-May17

Age-0

Age-1

Age-1

Preliminary data. Do not cite. Truncated length-frequency distributions of 

humpback chub captured near Fall Canyon (FAL) and Parashant (PAR).
Take-home messages

 Humpback chub were captured in all three sites in 

western Grand Canyon. We will probably choose Fall 

Canyon for our longer-term research.

 Growth patterns of juvenile humpback chub vary 

throughout Grand Canyon and seem to be mainly 

influenced by water temperatures.
Glen Canyon Dam Adaptive 

Management Group

US Fish and Wildlife Service

Kirk Young, Dennis Stone, Randy

Van Haverbeke, Mike Pillow, Chad 

Baumler

US Geological Survey

Clay Nelson, Mike Yard, Ted Kennedy, 

Glenn Bennett, Ken Sheehan, Mike 

Dodrill, Dave Ward

Ecometric Research 

University of Florida

AZ Game and Fish Department

Navajo Nation Department of 

Fish and Wildlife

Bureau of Reclamation

National Park Service

Also: Evan Anderson, Chelsie 

Arndt, Peter Atkinson, Luke Avery, 

Margeaux Bestard, Tanner 

Carothers, Mariah Giardina, Jake 

Hall, Ellie Johnson, Kyle Patterson, 

Kirk Burnette, Brian Dierker, Colin 

Evans, Dennis Harris, Jason 

Moore, Brett Stark, Jamie 

Townsend

Thanks!