Long-Term Experimental & 

Management Plan (LTEMP) Biological 

Opinion Conservation Measures 

Update

Technical Work Group Meeting

January 13, 2022

Kerri Pedersen, Bureau of Reclamation, Upper Colorado Basin 
Incidental Take Parameters – Tier 1 Action Initiation Triggers

Model estimates for adults are rounded to the nearest 1,000 and to the nearest 100 for sub-adults.

*No estimate was obtained for sub-adults in LCR in spring 2020 due to COVID-19 restrictions. The 2020 number was estimated 

by using data collected and abundance estimated from fall 2019.

Tier 1 – Early Intervention Trigger 2019 2020 2021 3-year average

Combined adult (>200 mm) humpback chub 

(HBC) in the mainstem Little Colorado River 

(LCR) aggregation and LCR

≤ 9,000 12,000 11,000 TBD

Not applicable. Trigger for 

adults based on annual 

population estimate

OR

Recruitment of sub-adult HBC (150-199 mm) 

does not equal or exceed estimated adult 

mortality

1) Sub-adult population estimate in LCR in 

spring

≤ 1,250 for 3 

years 2,600 1,000 TBD TBD but likely to be above 

trigger

OR

2) Sub-adult population estimates in mainstem 

in Juvenile Chub Monitoring (JCM) Reach in fall

≤ 810 for 3 

years

500 200 TBD TBD but likely below

trigger
Incidental Take Parameters – Tier 2 Action Triggers

Tier 2 – Action Triggers TRIGGER 2019 2020 2021

Mechanical Removal implemented

If adult HBC (≥200 mm) as estimated by the HBC 

population model <7,000 N/A N/A N/A

Terminate Mechanical Removal 

If predator index is <60 rainbow trout/km in JCM reach - - -

and immigration rate is Low (to be determined) - - -

OR

HBC population estimates > 7,500 - - -

and survival rates of sub-adult chub exceeds adult mortality for at least 

2 years - - -
Two-Tier Approach

 Tier 1 – emphasize conservation 

actions that take place during adult 

or sub-adult population declines.

 Tier 2 – predator removal if 

conservation actions are 

unsuccessful.
Humpback Chub – Tier 1 Action Triggers

• If the # of adult HBC (≥200 mm) in the LCR aggregation (includes the 

Colorado river mainstem and the LCR population) is < 9,000 

OR

• If recruitment of sub-adult HBC (150-199mm) ≤ estimated adult mortality 

such that:

• a) Sub-adult abundance <1,250 fish (3-yr average) in the spring LCR population 

estimates.

OR

• b) Sub-adult abundance <810 fish (3-yr average) in the fall mainstem Juvenile 

Chub Monitoring reach.
Trigger Response

Sub-adult decline in mainstem due to: 

• Poor recruitment

• Poor condition of adults in mainstem 

• Habitat quality in the Little Colorado River

• Predation by catfish & other species

Close coordination with USFWS

• Developing & updating dynamic response plan

• 535 sub-adults translocated above Chute Falls in the 

LCR

• 2022- action determined after larval production 

assessed
5-year trigger review

• LTEMP BO – requires review of triggers at least 

every 5 years

• 2021 review complete and officially 

submitted to USFWS

• Assessed/updated technical assumptions & 

conservation action options

• Improved clarity to document

• Identified topics for additional evaluation

• Western Grand Canyon

• Bioeconomic model

• Predator index
Conservation Measures as described in the 2016 

LTEMP ROD & Biological Opinion

Resource Conservation Measures

Humpback chub

Translocations

Monitoring

Non-native fish removal

Refuge support

Disease & parasite monitoring

Razorback sucker Monitoring

Determine hybridization extent

All native aquatic species

Non-native fish management

Evaluate temperature control

Evaluate fish passage

Southwestern willow flycatcher Monitor every 2 years

Yuma Ridgway’s rail Monitor every 3 years
Humpback Chub

Conservation Measures 2021 Updates

Translocations 535 sub-adults translocated above Chute Falls (response to trigger)

Monitoring 1 trip to Shinumo Inflow reach (September 2021)

1 trip to the CO river inflow around Bright Angel, Shinumo & Havasu Creeks (June 2021)

1 trip to Bright Angel Creek (June 2021)

2 trips to Havasu Creek (October 2020 & May 2021)

Non-native fish removal 26 brown trout & 96 rainbow trout (electrofishing)

8 brown trout & 18 rainbow trout (weir)

Refuge Support Collections occurred in spring 2021 but priority was placed on translocations above Chute Falls 

to respond to the trigger and no additional fish were added to the refuge in 2021.

Disease & parasite monitoring No Asian tapeworm monitoring occurred in the LCR in 2021

Monitoring for Asian tapeworm is scheduled to occur mainstem & LCR in 2022

USFWS & AZGFD examined all fish caught during routine monitoring for external parasites 

(Lernea & others)
Razorback Sucker

Conservation Measure 2021 Update

Monitoring • Monitoring trips in March (larval only), April, May, June, July, August, September 

(small-bodied only)

• 0 small-bodied razorback suckers

• 0 larval razorback suckers

Other Species Identified on Monitoring Trips

Non-native Species # of Juveniles # of Larvae

Brown trout 1 0

Channel catfish 1 0

Common carp 1 17

Fathead minnow 236 290

Plains killifish 321 64

Green sunfish 15 0

Red shiner 343 31

Western mosquitofish 21 6

Rainbow trout 163 6

Native Species # of Juveniles # of Larvae

Bluehead suckers 101 8,448

Flannelmouth suckers 2,707 14,253

Humpback chub 368 325

Speckled dace 3,429 3,471

Unidentified Cyprinid 1 0

Unidentified Sucker 2,044 22
Avian Surveys

Conservation Measure 2021 Updates

Partially assist with funding monitoring 

of Southwestern Willow Flycatcher 

(SWFL) every 2 years.

Surveys occurred in May, June & July.

Willow Flycatchers detected on first trip 

but no SWFLs.

Partially assist with funding monitoring 

of Yuma Ridgway’s Rail every 3 years.

No surveys planned or conducted – next 

survey planned for 2022.
All Native Aquatic Species – Temperature Control

Conservation Measure Updates

Explore efficacy of temperature 

control device

Temperature Control Device Update Provided in 2018: 

https://www.usbr.gov/uc/progact/amp/twg/2018-10-10-twgmeeting/Attach_01.pdf

Technical Services Center completed report in 2020 that reviewed options 

& identify unapplied technologies

(https://www.usbr.gov/tsc/techreferences/hydraulics_lab/pubs/PAP/PAP1184.pdf)

Technology search conducted by Yet2 with various ideas reviewed at April 

2021 TWG

Temperature Control Update Provided in June 2021

Includes history of progress on TCD since 1978

Power office looking at appraisal level study to examine bypass generation 

at river outlets

Potential Role of TWG: 

Identify environmental benefits of temperature control with clear 

objectives (target temperature, resources that benefit, etc.)
All Native Aquatic Species – Fish Passage

Conservation Measure Recent Progress

Evaluate means to prevent fish passage through 

the dam

2019-2020 Reclamation & DOE partnered to 

present a prize competition to evaluate fish 

passage. 

Reclamation initiated 3-part project to update 

2007-2009 Glen Canyon Dam forebay fish survey

• Utah State University is sampling the forebay 

various times over the next couple of years to 

characterize the fish community

• Reclamation’s Technical Services Center (TSC) is 

sampling forebay using hydroacoustics

• TSC engineering group is evaluating potential 

options for fish exclusion

Potential role of TWG: 

• Quantify risks associated with detections for 

each non-native species.

• Determine origination of detection (through the 

dam, from tributary, other source, etc.)
Results from October 2021 Lake Powell Sampling Trip

USU – Preliminary data – do not cite

n=66, 7 species

Depth (m)
Species Identified during Lake Powell October 2021 Trip

CCF = Channel Catfish

CRP = Carp

GZD = Gizzard Shad

SMB =Smallmouth Bass

STB = Striped Bass

TFS = Threadfin Shad

WAE =Walleye

USU – Preliminary Data – Do not cite
Questions?

Thanks to our partners for all the hard work and 

collecting the data to help us meet our 

conservation measures!
TWG Discussion

Temperature Control

Refine the problem statement that 

includes timing, temps, location

• Are we protecting native fish or 

disadvantaging non-native fish?

• When do we need what temperatures in 

what reach of the river? 

• When do we need to avoid what 

catastrophic temps in what reach of river?

Fish Passage

Discuss warmwater non-native 

detections below the dam 

• Quantify risks associated with detections 

for each non-native species (# of species 

at a certain river mile or during a certain 

time of year, or certain size or age class, 

etc.)

• Determine origination of detection 

(through the dam, from tributary, other 

source, etc.)