U.S. Department of the Interior

U.S. Geological Survey

Results from Colorado River 

Study Site and ongoing 

population modeling

Annual Reporting for FY13

January 28, 2014

Charles B. Yackulic* (U.S.G.S. – GCMRC),

Michael D. Yard (U.S.G.S. – GCMRC), 

Josh Korman (Ecometric Research Inc.), 

David R. Van Haverbeke (U.S. FWS, Arizona Fish and 

Wildlife Conservation Office), and

Lew Coggins (NOAA Fisheries, Sustainable Fisheries 

Branch, SEFSC, Beaufort Lab)

* Presenter – email: cyackulic@usgs.gov
Outline

 Juvenile chub survival and abundance in JCM. 

 Humpback chub dynamics - general patterns

 Modeling humpback chub dynamics for LTEMP

 Age 0 recruitment and movement. 

Annual Survival of HBC (40-99 mm) in the 

Colorado River Study Site

Preliminary Data Do Not Cite
Juvenile Abundance in JCM

month

Preliminary Data Do Not Cite
Outline

 Juvenile chub survival and abundance in JCM. 

 Humpback chub dynamics - general patterns

 Modeling humpback chub dynamics for LTEMP

 Age 0 recruitment and movement. 
The model and its parameters (excluding capture probabilities).

Yackulic, Yard, Korman and Van Haverbeke, in press
• Monthly survival generally 

increases with size and is 

higher in Colorado river 

than in LCR.

• Growth is much 

faster in LCR.

Yackulic, Yard, Korman and Van Haverbeke, in press
LCR – typical values based on 

2009-2012 data

Yackulic, Yard, Korman and Van Haverbeke, in press
LCR – typical values based on 

2009-2012 data

Yackulic, Yard, Korman and Van Haverbeke, in press
Colorado River – typical values 

based on 2009-2012 data

Yackulic, Yard, Korman and Van Haverbeke, in press
Colorado River – typical values 

based on 2009-2012 data

Yackulic, Yard, Korman and Van Haverbeke, in press
Size class 2 Size class 3 Size class 4 Size class 5

10

8

6

4

2

0

2012?

“I don’t trust your black magic models Charles...show me 

some data.” – skeptic

“Fine, lets look at all fish that were caught in 2009 in size 

class 2 and also caught (in any size class) in 2012. And 

let’s do it separately for the LCR and Colorado River.” – me
LCR

2009 2012

Size class 2 Size class 3 Size class 4 Size class 5

10

8

6

4

2

0

Yackulic, Yard, Korman and Van Haverbeke, in press
Colorado River Study Site

2009 2012

CR

Size class 2 Size class 3 Size class 4 Size class 5

6

5

4

3

2

1

0

Yackulic, Yard, Korman and Van Haverbeke, in press
LCR

CR

Size class 2 Size class 3 Size class 4 Size class 5

Size class 2 Size class 3 Size class 4 Size class 5

10

8

6

4

2

0

6

5

4

3

2

1

0

Yackulic, Yard, Korman and Van Haverbeke, in press
Other findings

 Evidence for both skip-spawning and residents.

 Larger adults spawn more frequently.

 Most size class 1 HBC leave LCR during monsoons.

 Adult Abundance – 11K (95% CI: 7-16K) 
Outline

 Juvenile chub survival and abundance in JCM. 

 Humpback chub dynamics - general patterns

 Modeling humpback chub dynamics for LTEMP

 Age 0 recruitment and movement. 
Preliminary Data Do Not Cite
Rainbow Trout Abundance in JCM reach

Juvenile Humpback Chub Survival

Fitted relationship between Juvenile

Preliminary Data Do Not Cite HBC survival and RBT abundance.
Rainbow Trout Abundance in JCM reach

Juvenile Humpback Chub Survival

Comparison to annual estimates. Preliminary Data Do Not Cite
Temperature 

- Celsius

Size transition rate (~growth)

Fitted 

relationship 

between 

monthly size 

transition rate 

(~growth) of 

juvenile HBC 

and 

temperature at 

two different 

RBT densities.

Preliminary Data Do Not Cite
Fitted 

relationship 

between 

monthly size 

transition rate 

(~growth) of 

larger HBC 

size classes 

and 

temperature.

Temperature - Celsius

Size transition rate (~growth)

Preliminary Data Do Not Cite
Backcasting

 Relationships I just showed based on 2009 – 2013 data.

 How well do these relationships explain behavior 

between 1990 & 2009?

 Observed Temp

 Modelled RBT 

 Abundance at LCR

 1990 Year 2009

1000

800

#RBT

(JCM)

200

0

Preliminary Data Do Not Cite
Dots and error bars - Coggins and Walters, 2009

Red dotted line - model developed for LTEMP EIS

Back-casted 

predictions are 

reasonably 

close to ASMR 

estimates (keep 

in mind that 

ASMR is known 

to smooth 

trends).

Preliminary Data Do Not Cite
Outline

 Juvenile chub survival and abundance in JCM. 

 Humpback chub dynamics - general patterns

 Modeling humpback chub dynamics for LTEMP

 Age 0 recruitment and movement. 
Recruitment in the ASMR context

 Recruitment to age 2

 combines a number of processes – initial 

amounts, compensation (density dependence), 

etc. 

 Ageing issues lead to smoothing
Fall LCR abundance

Preliminary Data Do Not Cite

Modified from Van Haverbeke et al. (Annual Reporting 2013)
LCR Recruitment Fall 

Abundance

?

Additions

to CR ?

ωω tt

1 − ωω tt

Time
Recruitment Fall 

Abundance

?

Additions

to CR ?

ωω tt

1 − ωω tt

Don’t necessarily care about Recruitment per se. But sure 

would be nice to be able to track (and backcast) additions to 

Colorado River

If we knew ωω tt, we could figure everything else out. 

Alternatively, we could estimate additions to JCM and expand 

for CR.
Analyzing abundances suggests lower (and 

highly variable) export when compared to 

estimates based on boulders only marking. 

Preliminary Data Do Not Cite
Why knowing additions to CR matters *LCR Spring Flow

How many juvenile HBC 

were actually in the 

Colorado River for LSSF?

Good

Bad

?

*Sum of daily means between Jan. 1 and May 31 at Cameron gauge.

Preliminary Data Do Not Cite
 Juvenile chub survival and abundance in JCM. 

 N still higher than 2009, but survival fairly low.

 Humpback chub dynamics - general patterns. 

 Big differences in growth/survival between CR & LCR.

 Modeling humpback chub dynamics for LTEMP.

 Mostly data-driven (using 2009-2013 data).

 Age 0 recruitment and movement. 

 Biggest modeling uncertainty. 

 Affects interpretation of previous CR treatments (e.g., LSSF). 

 Motivation for July LCR research. 
Acknowledgements

 US Fish and Wildlife Service

 Near Shore Ecology Group

 Mike Yard , Josh Korman, Lew 

Coggins, Maria Dzul

 Glen Canyon Adaptive 

Management Group

 Bureau of Reclamation

 Navajo Nation Department of 

Fish and Wildlife

 National Park Service