Conservation/Recovery of 

Colorado Pikeminnow in Grand Canyon

Biological Feasibility
 

KirK Young
	

April 14, 2021
	 Photo: Emery Kolb Collection, Northern 

Arizona University 
 

Colorado Pikeminnow in Grand Canyon 

Biological Feasibility
 

 A little background 

 What, How & Why? 

Photo: USFWS file photo, Upper Basin Recovery Program 

Preliminary/Draft; do not cite 
 

Colorado Pikeminnow -------1 

Historical Range 

Present Range 

Critical Habitat 

Nonessential 

Experimental 

NEVADA 

CALIFORNIA 

UTAH 

NEW MEXICO 

N 

t 

l<tLOMIETEIIS 

Background
 

Map: U.S. Fish and Wildlife Service, 2014
 Preliminary/Draft; do not cite 
Stanton’s 

Cave 4,000 ya 

Homolovi 

Site 

LCR ­

Salt Can. 

Cave 

Pikeminnow 

Archeological 

Records 

Catclaw Cave 

below Hoover 

Photo: YouTube 

Photo: Homolovi State Park Photo 

Photo: Bat Conservation International 

Background (2) 
 

 

 

 

 

 

Preliminary/Draft; do not cite 

Glen Canyon/Paria “Salmon”: Settlers – 1880s 

Stanton Christmas Meal – 1889 

Dynamite Fishing – Loper early 1900s

*Museum specimen (UM) - 1934 

Shinumo Creek “Salmon” 

- Nevills 1940; 1942 

- Goldwater 1940 

Tapeats Creek “Salmon” 

– Nevills 1948 

- J. Doerr 1948 

LCR @ Grand Falls 

“Salmon” 

– Miller (via Sykes) –

early 1900s 

Pikeminnow Historical 

Collections*/Reports 

Below Lava 14-16 “Salmon” – Kolb 1911 

Havasu Creek -

*Angler 1978 

1 

3

2 

Photo: Emery Kolb Collection, NAU 

Photo: Emery Kolb Collection, NAU 

Photo: National Park Service, Historic River Photo Collection 

Background (3) 
What & How? 

Phased Conceptual Approach: 

 Phase 1 Pikeminnow Viability/Feasibility 

Assessment
 

 Phase 2 - If Viable/Feasible (based on phase 1) 

Experimentation to Assess Feasibility. 

 Phase 3 - If Viable/Feasible (based on phase 2 

experimentation) Plan Development and 

Implement Recovery Actions (translocation(s) & 

monitoring etc.). 

Preliminary/Draft; do not cite
 
 

 

 

What & How? Phase 1
 

 Pikeminnow Viability/Feasibility Assessment 

 Paper exercise thru agreement with USGS
 

 USGS – science provider 

 Steering Committee to guide process – reps 

with management authorities in GC: AZGFD, 

NG&F, HG&F, NDOW, NPS, FWS, USBR 

 Expert elicitation (w/field visit) – Science Panel 

 Draft Report (spring 2021) 

 Stakeholder review 

 USGS OFR (fall 2021) 

Preliminary/Draft; do not cite
 
WHY?

Green River

Upper Colorado River San Juan River

Bestgen et al. 2018

Miller et al. 2018

Diver and Wilson 2018

Preliminary/Draft; do not cite
 

 

WHY? (2) 

 Supported by GCNP Comprehensive
 

Fisheries Management Plan
 

 Restore self-sustaining populations of extirpated fish species 

inc1uding Colorado pikeminnow, razorback sucker, bonytail, and 

roundtail chub as appropriate and to the extent feasible (if feasibility 

studies determine each species can be reasonably restored without 

impacting existing ESA-listed species). 

 Native Fish Thriving in Grand Canyon 
 

 

 

WHY? (3) 

“...These salmon were old friends of ours, being found 

from one end to the other of the Colorado, and on all 

its tributaries. They sometimes weigh twenty-five or 

thirty pounds, and are common at twenty pounds; being 

stockily built fish, with large, flat heads. They are not 

gamey, but afford a lot of meat with a very satisfying 

flavour.” 

E.L. Kolb 1915. 

Preliminary/Draft; do not cite 
U.S. Department of the Interior

U.S. Geological Survey

 

 

The Colorado Pikeminnow Reintroduction 

Feasibility Study 

Kimberly Dibble, Kirk Young, and Charles Yackulic 

GCDAMP Technical Work Group Meeting (virtual) 

April 14, 2021 

U.S. Department of the Interior 

U.S. Geological Survey 

Grand Canyon 

Photo: Emery Kolb Collection. NAU 
Presentation Outline 

 Study Overview 

 Objectives 

 Process steps 

 Report structure 

 Habitat assessment 

 Peak flows, base flows, water 

temperature, refuge/nursery 

habitat, forage base 

 Recommendations and 

next steps 

Photo: K. Dibble 
Presentation Outline, cont. 
 

 Study Overview 

 Objectives 

 Process steps 

 Report structure 

 Habitat assessment 

 Peak flows, base flows, water 

temperature, refuge/nursery 

habitat, forage base 

 Recommendations and 

next steps 

Photo: K. Dibble 
Study Objectives

 Synthesize information on habitat 

requirements for all life history stages

 Convene Science Panel and elicit 

expert opinion on potential habitat 

suitability in Grand Canyon and its 

compatibility with the existing fish 

community

 Recommend strategies for research to 

inform reestablishing and recovering 

the Colorado Pikeminnow in Grand 

Canyon

Grand Canyon

Photo: Emery Kolb Collection. NAU

Lower Yampa River

Photo: Burton (1987)
Steering Committee Science Panel 

Winkie Crook Kevin Bestgen 

Kim Yazzie Keith Gido 

Mark Grover Robert Schelly 

Brandon Senger Mark McKinstry 

Brian Healy Tildon Jones 

Emily Omana Smith Doug Osmundson 

Kirk Young Dale Ryden 

Process Steps 







Steering Committee 

 Meetings 2018-2019

Science Panel 

 Structured survey & text

 Workshop & river trip

(Sept. 2019)

Report completion 

 1st

nd 

draft: Dec. 2020 

 2 draft: May 2021

 OFR: Fall/winter 2021
Report Sections











Species description, distribution, 

and recovery efforts 

Habitat-related life history 

requirements 

Grand Canyon physical and 

biological characteristics 

Recovery viability in Grand Canyon 

Science Panel recommendations 

and next steps Illustration: J. Tomelleri 
 

Section Structure 





Topics and structure similar to SSA

SSA identified five habitat attributes most likely

to influence species viability

Life History Stage Habitat Attribute 

Spawning adult Peak flows 

Egg Base flows 

Embryo/larva (in substrate) Water temperature 

Larva (dispersed) Refuge/nursery habitat 

Juvenile (age 0) Forage base 

Juvenile (age 1-2) 

Sub-adult and Adult 
Presentation Outline (2)

 Study Overview

 Objectives







Process steps 

Report structure 

Habitat assessment 

 Peak flows, base flows, water

temperature, refuge/nursery

habitat, forage base

 Recommendations and

next steps

Photo: K. Dibble 
Maintain channel complexity, form backwater Peak Flows nursery habitats, clean cobble for spawning, and 

transport drifting larvae to nursery habitats 

 

Reduce vegetation 

encroachment & channel 

narrowing 

Sub-adult & 

Adult 

Spawning 

Adult 

Egg 

Embryo/ 

Larva 

Larva 

(drift) 

Age-0 

Age 1-2 

Maintain channel 

complexity and 

form low-velocity 

backwater habitats 

Transport drifting 

larvae to downstream 

nursery habitats 

Reduce reproduction by 

nonnative predators 

Trigger spawning 

migrations 

Redistribute 

sediment 

Clean substrate of fine 

sediment to provide

suitable spawning

habitat

Oxygenate interstitial 

spaces, facilitating hatching 

success 

Illustrations: J. Tomelleri; Photos: USFWS 2020 
 

 

 

 

–

Grand Canyon Flow Overview

Equalization 

Flows 

(Apr-Dec) 

Max PP 

Releases 

1983 

Flood 

Sediment 

Flushing 

Pre-Dam Post-Dam 

* * 

* 

Unpublished Data Do Not Cite 

Pre-dam: Large spring floods, low and steady summer flows

Post-dam: High daily hydropeaking, followed by MLFF regime

• Spring and fall-timed HFEs

• Releases up to Powerplant capacity
-

 

 

 

 

 

Spring High Flow Experiments

May-June 

March 26­

April 2

1996

March 4-8

2008

Pre-dam Post-dam 

Schmidt et al. 2001 

• Pre-dam spring flows higher in magnitude/duration & later than post-dam HFEs

• HFEs mobilize sediment off the bed for deposition on banks

• Create sandbars for recreational use and to help protect cultural sites

• Prevent vegetation encroachment into channel and on sandbars

• Form low-velocity backwater habitats (ephemeral)

• Other: Spring Disturbance Flow, March 2021

Rosi Marshall et al. 2010 
 

 

 

Science Panel: Peak Flows

Potential Benefits 

 Simulates spring flood

(shorter)

 Removes fine

sediment to improve

spawning gravels

 Creates backwaters

 May trigger spawning

migrations



Uncertainties 

May not substantially 

reduce embeddedness 

 Unclear if HFEs will

create well-oxygenated

substrate for egg

development

 Misses timing of larval

drift (summer)
 Base Flows Maintain stable nursery habitat in summer and
 

provide connectivity between spawning and 

foraging areas for adults
 

 

 

 

 

Provide water in 

channel for juveniles 

and adults 

Maintain low to 

zero velocity 

stable backwater 

habitats 

Transport drifting 

larvae to stable 

nursery habitat in 

summer 

Sub-adult & 

Adult 

Spawning 

Adult 

Egg 

Embryo/ 

Larva 

Larva 

(drift) 

Age-0 

Age 1-2 

Maintain connectivity 

between spawning 

and foraging areas 

Oxygenate interstitial 

spaces, facilitating egg 

attachment, incubation, and 

hatching success 

Illustrations: J. Tomelleri; Photos: USFWS 2020 
 

Glen Canyon Dam Operations 

 2016 Record of Decision for the Glen Canyon Dam

Long-Term Experimental and Management Plan,

Final Environmental Impact Statement (Alternative D)

LTEMP EIS, ROD 2016 

Unpublished Data – Do Not Cite 

Parameter Value 

Flow 

Maximum 25,000 cfs 

Minimum 5,000 cfs 

8,000 cfs 

Ramp Rates 

Ascending 4,000 cfs/hour 

Descending 1,500 cfs/hour 

Daily Flow Range 5,000 to 8,000 cfs 
Low or Steady Flow Experiments 

Experimental Releases 

allowed under 2016 ROD

 Low summer flows

 July, August, September

 2028 on; <10 maf release

 Achieve ≥14°C at LCR

 Macroinvertebrate

Production Flows

 May-August

 Steady releases on Sat-Sun

 “Give bugs the weekend

off” (TK and Jeff)

Low 

Summer
 

Flows
 

LTEMP EIS, ROD 2016 

Bug Flows 

Unpublished Data – Do Not Cite 
 

 

 

 

 

 

 

Science Panel: Base Flows

Potential Benefits 









Reliable source of 

water for movement 

Low/steady flows may

improve conditions

Native fish thriving 

despite altered flow & 

thermal regime 

Native fish use variety

of habitats (e.g., talus) 

Uncertainties 

 Hydropeaking may:

 Desiccate eggs

 Displace larvae into

Lake Mead

 Decrease stability &

persistence of

backwaters

 Impose energetic

cost with stage

change
Provide a thermal regime Water Temperature suitable for spawning, hatching, 

and growth 

 

Support juvenile, sub-adult, 

adult growth (18-30°C; 

ATU’s >47-50) Cue spawning and

adult migrations

(>16°C)

Support larval growth 

(18-30°C); lack of ‘cold 

shock’ conditions 

Facilitate larval 

survival (18-26°C) 

Sub-adult & 

Adult 

Spawning 

Adult 

Egg 

Embryo/ 

Larva 

Larva 

(drift) 

Age-0 

Age 1-2 

Facilitate embryo 

incubation and hatching 

success (18-26°C) 

Illustrations: J. Tomelleri; Photos: USFWS 2020 
Lake Powell Thermal Stratification

Vernieu et al. 2005
 
–

 

Annual Thermal Units in Mainstem

Glen Canyon Dam (RM -15) Lees Ferry (RM 0) Marble Canyon (RM 30) Upstream from LCR (RM 61) 

Downstream from LCR (RM 66) Bright Angel Creek (RM 88) 127-mile Creek (RM 127) National Canyon (RM 166) 

Diamond Creek (RM 225) Spencer Creek (RM 246) Pearce Ferry (RM 280) 

Unpublished Data Do Not Cite 
 

c 

0 

E 0.75 

E 

8 

>- 0.50 :=: 

:0 

~ 0.25 

e 

0.. 

0.00 -,-~-.--...---r--.-----, 

0 30 60 90 120 150 180 

Thermally Suitable Days 

Colorado pikeminnow 

(native) 

Current Thermal Suitability

Dibble et al. 2021; Illustration: J. Tomelleri 
 

Channel Catfish 

Colorado Pikeminnow Smallmouth Bass 

Red Shiner 

Dibble et al. 2021; Illustrations: J. Tomelleri 

Future Thermal Suitability
Unpublished Data – Do Not Cite

Unpublished Data – Do Not Cite

Tributaries
 

–

Cold Shock? What if CPM Spawn in Tributaries...

Δ 10.3°C Δ 7.7°C Δ 6.9°C 

Upstream Downstream 

Unpublished Data Do Not Cite 
 

 

 

Science Panel: Water Temperature
 

Potential Benefits 

 Western GC could 

support CPM 

 >16°C: Cue spawning 

 18°C: Support egg 

development & larval 

growth 

 Non-natives lacking 

 Pearce Ferry Rapid 

 Warmwater tributaries 

Uncertainties 

 Warming dependent on 

Lake Powell elevations
 

 Depressed summer 

temperatures & warmer 

winters (growth) 

 Sufficient cues for 

spawning (flow/temp) 

 Non-native invasion
 

with warming trend
 
Refuge/Nursery Habitat
 

 

 

 

Access to deep pools, 

runs, and eddies needed 

for foraging and refuge 

Adults target spawning riffles with 

cobble clean of accumulated 

sediment, upstream from low-velocity 

nursery habitats 

Long, unimpeded 

reaches support 

adult spawning 

migrations 

Tributaries could 

support spawning or 

growth needs 

Multiple low-velocity habitats 

in a reach provide refuge for 

larvae and juveniles 

Sub-adult & 

Adult 

Spawning 

Adult 

Egg 

Embryo/ 

Larva 

Larva 

(drift) 

Age-0 

Age 1-2 

Illustrations: J. Tomelleri; Photos: USFWS 2020 

Redundant, complex, lowvelocity habitat for spawning, 

rearing, and foraging 
GCD to Pearce Ferry: 476 km 

Pearce Ferry to Lake Mead: 26 km 

Freshwaters Illustrated 2021 

Photo: S. VanderKooi 

Grand Canyon 
Mainstem Spawning Substrate
 

Kaplinski et al. 2020, and Unpublished Data – Do Not Cite 

Freshwaters Illustrated 2021
 
 

40 Humpback Chub 40 Speckled Dace 

30 30 a 

a 

20 ab 20 

abc l be 

~ 0:: 

t 

c b 

u 10 I 10 j b 

~ b 

~ 1.[) t Ol 

+ 

E 0 0 0 

0 

- Cliff Sanci 

~ Backwater Debris Fan Talus Backwater Cliff Debris Fan Sand 

~ 

<fJ a a ~ 75 Bluehead Sucker 40 Flannelmouth Sucker 

~ <fJ 

c 

<ll 65 0 

c 

m 

4) 

:::1 

55 . 30 

45 

35 20 

b 

25 I b 

] b e 10 j t 

be be l c 

+ 

c c 

~ + ~ 0 

Fish in Backwaters & Other Habitat
 

Dodrill et al. 2015
 
Low Flows and Backwaters
 

Freshwaters Illustrated 2021
 
–

Tributary Habitats
 

Freshwaters Illustrated 2021 

Kanab Creek 

Unpublished Data Do Not Cite 
 

Science Panel: Refuge/Nursery Habitat
 

Potential Benefits 









Some suitable 

substrate available 

Monsoon season- new 

source of gravel 

Backwaters 

throughout GC 

HBC and FMS use 

other habitat types 

 Lake Mead inflow 

Uncertainties 













Spawning substrate
 

highly embedded
 

Exposed bars small 

Backwaters ephemeral
 

Larval fish- movement
 

No off-channel habitat 

or floodplain wetlands 

Non-native predationLake Mead 
Abundant forage base that exhibits low Prey Resources predation and competition from 

nonnative species 

 

 Larger invertebrates and small 

soft-rayed fishes support the 

Larger invertebrates support 

larval and juvenile growth 

(e.g., cladocerans, copepods, 

chironomid larvae) 

Sub-adult & 

Adult 

Spawning 

Adult 

Egg 

Embryo/ 

Larva 

Larva 

(drift) 

Age-0 

Age 1-2 

mixed diet of juvenile fish 

Low predation and competition 

from nonnative species essential 

for population viability 

Soft-rayed fishes 

support 

piscivorous adult 

diet 

Diatoms, algae, and first instars 

of invertebrates (e.g., 

chironomids) support larval diet 

Illustrations: J. Tomelleri; Photos: USFWS 2020 
~ 

LL 

~ 

<C 

.[ 

~ c: 

~ 

~ 

CD 

~ 

1,400 

1,200 

1.000 

800 

800 

400 

200 

0 

~8 44 6 

t=J Now Zealand Mudllllol 

- OWcnanod t=J Garrrnarus 

- Tlbfiad 

5211 55.7 64 95 123 7 164 5 1GB 1993 

Rillef Mile 

Fish 

• Rainbow troot 

• Flannelmouth sucler 

• Humpbacl: chub 

D Other 

Invertebrate 

• Mudsna'ls 

• Scuds 

• ludg~Norms 

• [artlw.<>rms 

0 Blilckties 

D lv'rd!ies 

LJ Caddsilies 

OOtller 

Aannelmouth sucker 

Midge and blackflv 

E 

::;: 

e 

<! 

2! 

g 

~ 

.g 

~ 

~ 

<I: 

30 E 

04 ::;: 

e 25 <! 

0 3 20 ~ 

" 0 

0 2 15 " lncraasmg i .,..._____ turbiditywth 10 a 

01 downsheam flow 

~ 

RM225 RM165 RM127 

E 

> 

-= 

Aquatic Invertebrate Production
 

Behn et al. 2010
 

Kennedy et al. 2013
 
Trends in Native Fish Abundance

Van Haverbeke and Dzul, Preliminary Data – Do Not Cite

AZGFD, FY19 GCMRC Annual 

Report

CPUE (fish/hr)

Illustrations: J. Tomelleri
 

Predation Potential
 

Gapes Com parison 

Rainbow trout 

Brown trout 

Smallmouth bass 

Largemouth bass 

Striped bass 

100 

80 Flathead catfish 

Vertical Gape (mm)

Bullhead catfish ~75 Channel catfish 

Northern pike 

Colorado pikeminnow 

60 

40 

~39 

20 

600 mm predator 

0 200 400 600 800 1000 

Total Length (mm) 

0 

D. Ward, In Review, NAJFM; Photos: D. Ward; Illustrations: J. Tomelleri, C. Iverson 
–

Predation Vulnerability
 

Difference in predation vulnerability
 

% Survival 

120
 

100
 

80
 

60
 

40
 

20
 

0
 

Flannelmouth sucker Humpback chub 

Prey Species 

D. Ward, Unpublished Data Do Not Cite 

Illustrations: J. Tomelleri 
 

 

Science Panel: Forage Base
 

Potential Benefits 

 Abundant prey base 

for sub-adults/adults 

 Few non-native spinyrayed fishes 

 FMS abundant 

 FMS selected over
 

HBC in lab trials
 

affected at pop level 

 HBC likely not 

Uncertainties 

 Low algal/invertebrate 

productivity to support 

larval/juvenile fish 

 Food web unstable, 

poor insect diversity 

 Low production of 

small fishes (juveniles) 
Presentation Outline (3)
 

 Study Overview 

 Objectives 

 Process steps 

 Report structure 

 Habitat assessment 

 Peak flows, base flows, water 

temperature, refuge/nursery 

habitat, forage base 

 Recommendations and 

next steps 

Photo: K. Dibble 
General Thoughts from SP 

 Habitat attributes could satisfy some, but 

perhaps not all life history requirements
 

 Substrate may not support egg development 

 Uncertainty on stable, redundant nursery habitats 

for larval and age 0-2 fish 

 Low productivity to support larval & juvenile fish 

 Potential for low survival of early life history 

stages may create a recruitment bottleneck
 
 

 

 

 

 

General Thoughts from SP 

 Habitat may support adult and sub-adult 

growth, foraging, home range development, 

migrations, and spawning 

 Native populations of HBC and FMS thriving in 

western GC, even though habitat quality 

appears low relative to Upper Basin rivers 

 HBC exhibit high condition factor, reside in
 

habitats that support multiple life stages
 

 FMS are numerically more abundant 

 GC lacks warmwater non-native predators 

 GC providing good habitat for endemic natives 
 

 

 

 

Recommendation
 

The Colorado pikeminnow Science Panel recommends that wildlife 

resource managers pursue Phase II, which focuses on 

experimentation to assess reintroduction feasibility. 

To meet this goal, the Panel developed a preliminary list of research 

questions to consider during the experimentation phase. 

While not exhaustive, this list provides fodder for a discussion of future 

order to better inform a decision on Colorado pikeminnow reintroduction into 

research priorities to resolve key uncertainties related to habitat suitability in 

Grand Canyon (i.e., Phase III). 
 

Questions?
 

Photo: Robert O. Hall, Jr. 

kdibble@usgs.gov; (928) 556-7327