Drivers of Demographic Rates in 

Translocated Humpback Chub 

Populations and an 

Annual Update

Brian D. Healy1,2,3, Phaedra Budy5,2,3, Mary M. Conner4,3, 

Emily Omana Smith1, Robert C. Schelly1, Rebecca Koller1

1Native Fish Ecology and Conservation Program, Grand Canyon National Park, Flagstaff, AZ 86001, 

USA

2Department of Watershed Sciences, Utah State University, Logan, UT 84322, USA

3Ecology Center, Utah State University, Logan, UT 84322, USA

4Department of Wildland Resources, Utah State University, Logan, Utah, 84322-5210

5U. S. Geological Survey, Utah Cooperative Fish and Wildlife Research Unit, Utah State University, 

Logan, UT 84322
Presentation Outline

• 2020 translocation updates

• Summarize an analysis of hypothesized 

relationships between humpback chub vital 

rates (e.g., survival, recruitment) and 

environmental variables

• Demonstrate value of tributaries as 

“mesocosms” to understand humpback 

chub ecology and population dynamics

• Next steps - 2021
Project Title: Humpback Chub Translocations

• Project elements: not included in AMP workplan, relates to G.7 (Chute Falls 

translocation)

• Project Objectives: Translocate humpback chub to tributaries outside the LCR

• LTEMP goal addressed:

• “Meet humpback chub recovery goals, including maintaining a self-sustaining population, spawning 

habitat, and aggregations in the Colorado River and its tributaries below Glen Canyon Dam”

• Funding amount and source: FY2020 - $405,855, Bureau of Reclamation, other 

funding – NPS, Utah State, USU Center for Col. River Studies, Grand Canyon 

Conservancy

• Cooperators - see final slide

• Products FY2020:

• Healy, B. D., E. C. Omana Smith, R. C. Schelly, M. A. Trammell, and C. B. Nelson. 2020. 

Establishment of a reproducing population of endangered humpback chub through 

translocations to a Colorado River tributary in Grand Canyon, Arizona. North American 

Journal of Fisheries Management 40:278–292.

• Annual report to Reclamation

• Healy et al. in prep. Invasive trout, floods, and density-dependent drivers of translocated fish 

populations in dynamic semi-arid-land tributaries.
Introduction - Goals

• Conservation measures:

• Focus: Shinumo, Havasu, Bright 

Angel (others as deemed 

appropriate)

• NPS Comprehensive Fisheries 

Management Plan (2013):

• Measures of abundance (min. 

population goal ≥ 200)

• Demographic rates (survival, 

growth, etc.) compared to LCR
Translocation 

Sites
Translocation Logistics

 Humpback chub 

collected as juveniles 

from the Little Colorado 

River

 Flown to the canyon rim, 

transported by hatchery 

truck to AZGFD or 

USFWS hatchery 
Translocation Logistics

 Rearing for 8-12 months

 Parasite & disease 

treatment

 PIT-tagging

 Weight and length
Translocations 2009 - 2020
Translocation 

Activities: 2020

• Bright Angel Creek translocation

• June 9, 2020

• 415 juvenile humpback chub, 

collected in 2019

• Completed:

• Shinumo Inflow monitoring (2 trips)

• Havasu monitoring (October)

• COVID cancellations:

• LCR collection, May-June

• Havasu spring sampling, May
Results - Review

• Havasu Creek: 

• Reproducing population 

established

• Healy et al. 2020. North American 

Journal of Fisheries Management 

40:278-292

• Shinumo Creek:

• Comparable growth/survival to 

LCR, 2009 – 2011

• Spurgeon et al. 2015. Transactions of 

the American Fisheries Society 

144:502-514

• Extirpation with 2014 fire and 

flood

• Flushed out by the flood? Or 

Mortality?

• Next: study populations to learn 

about humpback chub ecology 

and drivers of demographic 

rates
Conceptual Model
Habitat Differences between Sites
Differences in 

seasonal and annual 

hydrology between 

translocation sites

 Havasu Creek:

 Little spring runoff

 Intense, short-duration 

monsoon season 

flooding

 North Rim tributaries:

 Representative of 

Shinumo Creek

 Difference: winter 

snowmelt runoff
Differences Between Sites
Methods – Monitoring and Data Analysis

• Mark-recapture monitoring

• Hoop – netting:

• Shinumo Creek – June, September, 

2009 – 2014

• Havasu Creek – May, October, 

2011- 2020

• GCD AMP and NPS monitoring:

• Mainstem electrofishing/hoopnetting

• Portable antenna detections

• Fixed PIT-tag antenna detections 

(Shinumo, LCR, Bright Angel)

• Models tested:

• Growth, survival, recruitment ~ 

f(temp./season, flooding, rainbow 

trout, HBC abundance)
Results – Drivers of Juvenile Growth Rates

• Top models:

• Havasu growth:

• Season x flood-frequency (+ in 

summer)

• humpback chub abundance (-)

• R2 = 0.84

• Shinumo growth

• Rainbow trout x season (-)

• flood frequency (+)

• R2 = 0.69
Results – Havasu Creek Survival

• Monthly survival:

• Group effect 

• Constant and lower – in 

situ fish

• Humpback chub density (-)

• Flooding/temperature (+)

• Survival comparable to LCR

• Supports hypotheses –

• Density-dependence

• Positive impact of 

flooding
Results – Havasu Creek Recruitment

• Recruitment:

• Natal year rainbow trout abundance (-) 

• Natal year humpback chub abundance (-) 

• Flooding (weak negative effect)

• Population growth rates (λ):

• Suggests population growth driven more 

by recruitment than adult survival

• Management implications:

• Manage trout when abundant

• Carefully consider augmentation
Results – Abundance and Population Goal

• Population goal: ≥ 200

• Suggests carrying 

capacity ~ 300 – 400

• Decision:

• Is augmentation 

needed?
Results – Shinumo Creek Survival

• Monthly survival:

• Survival comparable to 

LCR most intervals

• Mortality event 

associated with fire/flood 

in 2014

• Observed spawning in 

Shinumo mouth – 2019

• Young-of-year (7) 

captured 2020
Temperature Effects?

• Colorado River – warming temperatures reduce rainbow trout impact? 

• Yackulic et al. 2018 – Col. River

• Ward et al. 2015 – laboratory

• Havasu and Shinumo Creeks -

• Negative demographic and growth impacts under natural (warmer) 

temperatures 

• Or increase metabolic demand and food consumption, increasing effects of 

competition or predation?
Summary

• Translocation sites provide natural “mesocosms” for study of 

population dynamics

• Natural flow and temperature regimes

• Rainbow trout negatively impact humpback chub:

• Growth rates (Shinumo)

• Previous food web work – dietary overlap*

• Recruitment (Havasu) 

• Note: no reproduction/recruitment noted in Shinumo

• Density-dependent growth & survival in Havasu Creek

• Natural flows and monsoon flooding may benefit (food 

delivery)

• Exceptions: 

• Extreme fire/flooding
Next steps.....

• Determine whether augmentation of Havasu Creek is 

necessary:

• Genetic testing in progress through GCMRC

• Develop plans to reinitiate translocations to Shinumo Creek: 

• How will we manage rainbow trout? 

• Continue translocations to Bright Angel Creek:

• Further monitoring is needed to assess survival, growth, 

etc.
Thank you!