Humpback Chub Tributary Translocation Monitoring

GCDAMP Annual Reporting Meeting January 11, 2022

Emily Omana Smith, Brian Healy, Bob Schelly, Rebecca Koller

Design by Amy Martin 
Acknowledgements
Today

• Why translocate?

• Shinumo Creek

• Havasu Creek

• Bright Angel Creek

• Come join us!
Translocation 

Objectives & Indicators

Evaluation of success: (a) retention in the translocation creek for a minimum of one year, (b) similar or 

increased survival of juveniles relative to survival in the LCR or Colorado River, (c) similar or increased 

growth rates relative to the LCR and mainstem, (d) contributions to the mainstem aggregation, (e) 

evidence of successful reproduction, (f) evidence of recruitment to maturity (Trammell et al. 2012, 

NPS-CFMP 2013). 

Why translocate?

Success measured by 1) the 

establishment of a second spawning & 

recruiting population or 2) sufficient 

survival and growth to provide a 

rearing opportunity to augment the 

local aggregation (CFMP 2013)
Project 

Area

The project area, including the Little Colorado River which is the source for collections of 

humpback chub for translocations, and translocation sites including Shinumo Creek, and 

Bright Angel Creek, Havasu Creek in Grand Canyon National Park (green boundaries).
Translocations outside of the Little Colorado River
Translocation-related field work, FY 2021

Five monitoring trips: on the Colorado River in the Shinumo Inflow reach (1 trip); in the 

Colorado River inflows around Bright Angel Creek, Shinumo Creek, and Havasu Creek (1); in 

Bright Angel Creek (1), and in Havasu Creek (2). 

One targeted winter invasive trout control trip was implemented at suspected sources of 

trout production in tributaries and tributary mouths along the Colorado River between 

Nankoweap Creek and Surprise Creek. A total of 111 rainbow trout and 19 brown trout were 

captured during this trip.
Surveillance for potential invasive species

Seine nets were used for presence/ 

absence surveillance of potential 

invasive species in hotspots 

including Kanab and Surprise creeks 

and large backwaters during June 

and September mainstem 

translocation monitoring trips. 

During these efforts, invasive green 

sunfish, plains killifish, and fathead 

minnows were captured along with 

native fish species.
Shinumo Creek
Shinumo Creek 2014 Galahad Fire & Flooding
Shinumo Creek Survival

A joint-live recapture/resight model 

“Barker’s model”- estimate survival for HBC 

translocated to SHI (using data collected by NPS, 

AZGFD, GCMRC, and USFWS in Shinumo Creek, the 

Little Colorado River, and the mainstem Colorado 

River; Healy et al. in review). 

Survival was comparable to that in the LCR 

(Yackulic et al. 2014) except for the intervals 

following the Galahad Fire and subsequent 

ash-laden flood that apparently led to high 

mortality of translocated HBC (Healy et al. in 

review). 

No recent estimates of survival due to low 

numbers of resights. 

Survival (accounting for site fidelity) estimates over time for translocated HBC relative to survival in 

the LCR (dashed line; Yackulic et al. 2014). Triangles indicate survival estimates for each interval 

between sampling events, and the dashed reference line is a survival benchmark for the LCR for 

comparison to Shinumo HBC survival (standardized to a monthly rate). The gray vertical bar 

indicates the timing of the Galahad Fire and subsequent ash-laden flood that occurred in July 2014. 

Source: Healy et al. (in review). 
Shinumo Creek- Contribution to Inflow aggregation 

• The proportional contribution of translocated fish 

to the SHI aggregation was generally higher than 

non-translocated fish through 2014 

• A higher proportion of non-translocated fish

entered the population in 2015-2016 

• Both groups’ abundance declined after 2016. 

• Cautious with absolute abundance estimates due to 

variation in sampling effort over time, but:

• Relative contributions of groups to the aggregation 

abundance at a given time and to the super 

population should be considered more reliable. 

• Abundance estimates for the non-translocated group 

are within a range estimated by Valdez and Ryel

1995 & Persons et al. 2017. GCMRC/FWS CPUE 

results also showed increases in HBC in the area 

following translocations (Persons et al. 2017)

Results of POPAN mark-recapture modeling showing differences in proportional 

abundance of non-translocated HBC and those translocated to SHI (2009 – 2014) to 

the SHI Inflow aggregation (between RM 108.3 and 109.5). 

POPAN parameter estimates include the probability of entry of individuals into the 

population through births or immigration during each sampling occasions 

(recruitment), apparent survival (φ), abundance on each occasion (N෡), and a superpopulation abundance (N*). N* is defined as the total number of individuals estimated 

during the entire study period (Schwarz and Arnason 1996). 
Havasu Creek
Havasu Creek Body Condition

The mean relative weight of May 2021 

Havasu HBC (>120 mm) was 89.48 (95% 

C.I. = 78.92 – 100.04). Median relative 

weights were slightly lower than the 

established standard (i.e., <100) but 

similar to past years (median range: 

79.5 – 103.7, 2011 – 2019)

Estimates lower than the standard may 

relate to HBC density and lack of 

flooding (Healy et al. in review). 
Recapture / Resights

A joint-live recapture/resight model “Barker’s model”-

estimate survival for HBC translocated to HAV (using data 

collected by NPS, AZGFD, GCMRC, and USFWS in HAV, the LCR, and 

the mainstem Colorado River; Healy et al. in review). 

Recent & more widespread use of portable PIT tag 

antennas deployed by FWS, GCMRC, and NPS appears 

to significantly augment encounter histories and to 

improve estimates. 

72 Havasu-translocated HBC had been detected in the 

mainstem Colorado River between 2011 and 2019 –

while 34 were detected on the NPS-deployed portable 

antenna in the mouth of Havasu Creek from June- July 

2021 alone. 
Havasu Creek 

Apparent Survival 

Varied over time (bottom) and by cohort 

(top), ranging from 0.44 to near 1.0. 

No environmental covariates were included 

in alternative survival models- previously 

survival was found to vary with HBC density 

and flood frequency (Healy et al. in review). 

Survival is high for HBC translocated to 

Havasu and comparable to that in the Little 

Colorado River (Yackulic et al. 2021, 0.4 –

0.9). 

Survival estimates in the time-varying model were scaled to be comparable to an annual rate. 

The last estimate in 2021 is confounded with time-varying recapture/resight probability. 
Havasu Creek Abundance Estimation 

The abundance estimate was 215 (95% CI 200 – 264)- considerably higher than the previous 

abundance estimate generated in spring of 2019 (116, 95% CI 109 – 153) 

Genetic management plans recommend at least 200 HBC be maintained at each translocation site 

if reproduction occurs, with occasional augmentation with LCR fish as necessary to maintain 

genetic integrity (USFWS 2010, Van Haverbeke et al. 2016). The abundance now exceeds the 

population goal established in the NPS CFMP (2013). 

The 2021 Havasu Creek population consists of 85% non-translocated fish, or wild fish. 
Havasu Creek Recruitment & Population Growth

A temporal symmetry model (Pradel 1996) was 

used with non-translocated HBC:

• recruitment estimate: 0.52 (95% C.I. = 0.32 - 0.71) 

• seniority probability estimate: 0.66 (95% C.I. = 0.54 

– 0.76)

• population growth estimate: 1.39 (95% C.I. = 1.09 –

1.77). 

Population growth estimates have remained at 1 

(i.e., 95% CIs overlap 1) or above 1 for the last 

several years in Havasu Creek, indicative of a 

stable or increasing population. 

The higher 2021 seniority probability estimate 

(~0.50) relative to previous years indicates that 

this increase was more driven by high adult 

survival than recruitment.
Bright Angel Creek- preliminary
Bright Angel Creek Growth & Body Condition

• Translocation cohorts differed in size at release, and 

growth in HBC declines with age and size (Pine et al. 

2017)- growth is difficult to compare. The average 

size of 2020 translocated HBC was similar to the 

2009 & 2010 cohorts translocated to SHI. 

• Annual total growth of 2020 cohort averaged 30.7 

mm between June 2020 and June 2021. This rate is 

similar to annual growth rates for the 2009 & 2010 

SHI cohorts (Spurgeon et al. 2015), but less than 

those published for the LCR (Stone et al. 2020). 

• Median relative weights were also slightly lower 

than the published standard (i.e., <100) in June 

2021- perhaps due to high trout densities (2020-

2021) and a lack of flooding (summer 2020) (Healy 

et al. in review, Behn and Baxter 2019)
Bright Angel Creek PIT Antenna Detections

138 unique HBC detected since installation in May 

2018 (translocated & non-translocated)

PIT-tag antenna array was destroyed during a flash 

flood on August 17, 2021

28 unique HBC (16 released in 2018, 11 from 2020, 

1 RM 79.9) in FY 21

Most of the FY 2021 detections occurred between 

April and June- conditioning & spawning

After reinstallation, detection data will be 

incorporated into future mark-recapture models to 

estimate survival, emigration rates, and potentially 

abundance for translocated HBC
Summary

449 HBC captures during monitoring or trout suppression trips in FY 2021 including 355 in HAV, 46 in 

BAC, 48 in the combined tributary inflows (BAC, SHI, and HAV). PIT tag antennas also detected 34 

unique translocated HBC in the HAV inflow and 28 unique HBC in BAC. PIT tag antenna data improve 

survival estimates.

In HAV, survival was relatively high and stable and comparable to that found for HBC in the LCR. The 

2021 abundance estimate of 215 exceeds the population goal of 200. Reproduction and recruitment 

of the translocated population of HBC in HAV, first observed in 2016, continued. 

SHI survival was comparable to the LCR until the Galahad Fire (2014). Mainstem abundance and 

survival modeling results before & after the fire suggest translocations to SHI can have important 

contributions to mainstem HBC aggregations. 

Continue to gather data to assess BAC translocations and plan to install another PIT Tag antenna 

array. Preliminary data point to potential seasonal movements for conditioning and spawning.

During surveillance of potential invasive species hotspots, captured green sunfish, plains killifish, 

and fathead minnows along with native fish species.
Questions?