Effects of 2003/2004 GCD Enhanced 

Flows on the Early Life History S

Rainbow Trout in Glen Can

Josh Korman, Matt Kaplinski

Joe Hazel, Ted Melis

GCMRC

Lew Coggins Barbara Ralston Car

ol Fritzinger

Funded from FY03/04 GCDAMP E

xperimental Flow Program
Objectives of Project

I. Estimate magnitude of incubation mortality (

caused by Jan.-Mar. fluctuations and to prediflow regimes.

II.

Quantify spawning habitat preference (depth

to determine how discharge controls spawnin

III.

Evaluate factors that determine recruitment o

trout (emergence timing, growth, habitat shifand their linkage to GCD operations 

–

Useful in the design flow regimes targeted at regula

–

As a monitoring tool to assess impacts from GCD o

multi- or within-year comparisons of different flow 

IV.

Evaluate the extent of successful reproductio

between Lee’s Ferry to the LCR confluence

–

Need to quantify the sources of reproduction (Glen 

mainstem vs. Marble tributary) if we are trying to r
3 Good Reasons to Focus Ef

Glen Canyon

1. Need to understand the linkage between G

trout recruitment in Glen Canyon as it wi

2. Logistically, Glen Canyon is a much mor

environment to work in. Understanding fbe transferred downstream.

3. If emigration of trout from Glen Canyon 

population in Marble Canyon, recruitmenhave direct consequences on population i
Conceptual Model of Incubation Mor

Timing of spawning

Morphology

Homing behavior

GCD flow regime

Redd Elevations

Intergravel

water

temperature

Incubation Mortality
#

#

# #

# #

Site Type

# Intensive# RAT

Location of Spawning Areas

in Glen Canyon
Redd Counts

2004

0

200400600800

10001200

Nov-23

Dec-23

Jan-21 Feb-04 Feb-29

Mar-14

Mar-28

Apr-18

# of Redds Present RAT

FM, PL, PH
Total redds for year and timing of excava

from raw counts and survey 

2004

0

200400600800

10001200

Dec-01

Dec-31

Jan-30

Feb-29

# of Redds Present

0

1000200030004000

Dec-01

Dec-31

Jan-30

Feb-29

Total Redds Excavated2004 2003

# Redds = AUC/Survey Life
Redd Location and

Elevation at 

Four Mile Bar, 2004

Four Mile Bar (2004)

144 123 211 367 79 33 22

0

20406080

100

Feb-04 Feb-29 Mar-14 Mar-28

Apr-18

May-02

May-22

% of Redds

15-2012-158-125-8<5

#

#

#

# #

#

#

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#

#

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#
System-Wide Redd Hypsom

Inte

n

sive + RAT (2004)

397 443 681 962 439 271 

0

20406080

100

Feb-04

Feb-29

Mar-14

Mar-28

Apr-18

May-02

% of Redds
Intergravel Temperature

Four Mile

B

ar (

2

0

0

4)

5

10152025303540

Feb-01 Feb-16

Mar-02

Mar-17 Apr-01 Apr-16 May-01 May-16 May-31

Max. Daily Temperature (C)

510121517.5Lethal Limit

P

o

w

erline B

ar (2004)

5

10152025303540

Feb-01 Feb-16

Mar-02

Mar-17 Apr-01 Apr-16 May-01 May-16 May-31

Max. Daily Temperature (C)

5101518Lethal Li

mit

F

o

u

5

10152025303540

Feb-01 Feb-16

Mar-03

M

Max. Daily Temperature (C)

P

o

w

5

10152025303540

Feb-01 Feb-16

Mar-03

M

Max. Daily Temperature (C)
Summary of Egg/Alevin Mor

All 

Stages

< 5 kcfs 5-8 kcfs 8-12 

kcfs

1

k

2004Total 2142 1069 374 401 % Lost 33

0

0 100 

2003Total 4033 1811 1019 716 % Lost 23

0

0 79 
Comparison of 2004 Redd Mo

with Other Scenarios

Scenario % R

2004 2004 with ROD Flows 

Jan: 12-20 with Sunday 12

Feb-Mar: 8/15 with Sunday 8

2004 + Extend Flux. Through Apr. 2004 + Sunday Steady Flow of 5 kcfs Extended Flux and Sunday S

teady 5 kcfs 

Pre-ROD 
Conclusions from Redd Morta

Very unlikely to see any effect of 2003/

Mar. flows on recruitment to age 1 Glen Canyon:

1. Little difference in redd mortality relative to n2. Additional redd mortality likely compensated 

density-dependent mortality at later life stages

density dependence

# of age 1 recruits No density de

# of surviving eggs
Estimation of Incubation Survival and Gr

Use, and Survival of Young-of-Year (Y

Egg Depositio

Emerging (

Food A

vailability

C

ompetition

Growth

Habitat Use

Ontogenetic Habitat Shifts

# Survivin

Incubation survival Spawning site selection

Intergravel temperature

GCD Flow

# Surviving t

# Surviving t

Predation risk 
Habitat Types

Low angle habita

t

20-60 mm YoYDebris fans, cobble and s

and 

50% of shoreline length Glen 20 sites/trip sampled by back600 m/trip sampled, or 2% oSteep angle habit

a

t

> 60 mm YoYTalus slopes40% of shoreline length in G20 sites/month sampled by b1000 m/trip sampled, or 5% 
Statistical Catch-at-Age M

•

Obtain length-frequency data for multiple s

•

Use simple population and observation mod

length-frequency for these same periods bafollowing parameters:

–

# of fish hatching per week

–

Survival of fish each week

–

Growth rate (otolith data)

–

Vulnerability

•

Estimate parameters (and uncertainty) by co

predictions to the length-frequency observa
Statistical Catch-At-Age Analysis 

0

50

100150200

20 30 40 50 60 7

For

klengt

h (

m

m)

Catch

Ma

y July

Traditional SCA

(Adult / catch from fishery)

Hyp

(Juvenilfrom scisurveys

Size-at-age Imprecise PreciseCatchability Variable ConsisteHabitat use Minor Signific
Model Structure

NS,a,t = (NS,a-1,t-1 + NL,a-1,t-1 * M

O

Va) * S

S

NL,a,t = NL,a-1,t-1 * (1 -

MOVa) * S

L

( ) ( )( )

N

R dt

t

t

t ∫ t t

−

−

−

=

−

1

1 1

0, 1

α

β

θ

θ

a

L

+

=

1

Population Dynamics Observa

Recruitment (# hatching/wk) Growth (ag

Movement Vulnerabilit

# Alive (/age and wk)

MovSl MovSl

MovSl

a MovHalf l

l MOV

+

=

Ch,l,t = Nh,

# Caught (/len

h l VulH

V

, =

LorenzenSize-survival

q = C

obs

h 

Catchability 
Fit Parameters by maximizing li

assuming error is Poisson-dist

( , , , , , , )

, ,

p

h l t h

h

h

e

k

S VulHalf VulSl MovHalf MovSl

− 

L

α

β

=

rt

Sh, (t,t+i)

Sum likelihood across habitat types (h), length And sampling trips (t)Maximize likelihood using iterative search proc
Length-at-Ag

Otolith measurements 

Fisheries and 

0

20406080

10

0

12

0

0

3

0

6

0

9

0 12

0 15

0 180 210 240 270 

Ag

e from H

atch (da

ys)

Forklength (mm)

L

o

w (

2004)

L

o

w (2

0

0

4) - 

M

L

E

Steep (

2004)

Steep (

2004) -

M

L

E

2003 -

M

L

E
Hatch (Recruitment) Tim

0

100200300400500

1-Nov

1-Dec

31-Dec

30-Jan

29-Feb

30-Mar

29-Apr

29-May

28-Jun

Hatc

h Date

# of Fry Hatching Per Wk

B

ack-c

alculated from Fry

R

edd C

ount (with 3

3 d

a

y shift)

n = 4,900
Daily High Flow 

(9:00 am – 8:00 pm)

Daily Low Flow

(1:00 am – 6:00 am)

Varial Zone

river bank

cross-section

8,000

10,00012,00014,00016,00018,00020,000

Jun-04

00:00

Jun-05

00:00

Jun-06

00:00

Discharge (cfs)

And on Sunday Let them 

0

20406080

100120140160

Day N

Low Angle (bakpac

# YoY Per 100 m

High FlowLow Flow
Steep A

n

gle - B

oat

0

255075

100125150175

20 30 40 50

6

0 70 80 90 100 110 120 130

Forklength (

m

m)

# Per 1000 m

n = 3393

Lo

w A

ngle - B

ackp

ack

0

255075

100125150175

20 30 40 50

6

0 70 80 90 10

0 110 120 130

Forklength (

m

m)

# Per 1000 m

AprilMa

y

Ju

n

e

JulyAu

g

u

st

S

e

ptember

No

v

e

m

b

er

D

e

c

e

mber

n = 1502

0

5,000

10,00015,00020,00025,000

1-Sep-03

Discharge (cfs)

Obs

F
L

o

w Angl

e - E

arly 

S

e

a

son

0

50

100150200250

20 30 40 50 60 70 80 90

# Fis h /1000 m

01-Apr06-May10-Jun01-Jul

01-Apr

06-May

10-Jun

01-Jul

Low Angle -

Late Sea

son

0

20406080

100120

20 30 40 50 60 70 80 90

Forklength (m

m)

# F is h/1000 m

05-Aug09-Sep04-Nov02-Dec

05-Aug

09-Sep

04-Nov

02-Dec

St

e

ep 

0

20406080

100

20 30 40 50 60 

Steep 

0

20406080

100120140

20 30 40 50 60 
Uncertainty in Monthly Estimates of Surv

Low Angle

0

0.

2

0.

4

0.

6

0.

8

1

0.5 0.6

0.7 0.8

0.9 1.0

W

eekly S

urvival

R

ate

Probability

JuneJulyAugustS

eptember

N

o

ve

mber

Steep An

gle

0

0.

2

0.

4

0.

6

0.

8

1

0.5 0.6

0.7 0.8

0.9 1.0

We

e

kly S

urviv

al R

ate

Probability

0

5,000

10,00015,00020,00025,000

1-Sep-03

1-Nov-03

1Jan04

Discharge (cfs)
Conclusions

• Daily fluctuations are reducing YoY growth rates 

– Increased growth on Sundays seen in otoliths when flows are near minimu

holding

– Literature

• Juvenile trout do not fully compensate for increased water flow by changing mic• After initial velocity increases fish move closer to the streambed, and then, if ne

1994). 

• Foraging area theory (Walters and Jaunes).

• Sudden changes in flow (Aug-Sept) increase YoY Mortality R

or displacement

– Reduced survival will be compensated by increased survival rates during w

– Ultimately need to compare survival predictions with long-term recruitmen

AGF).

• Catch-at-age model potentially valuable monitoring tool to ass

year effects of GCD operations.

– Requires assumption that size-dependent catchability is constant over sam
Is There a Better Way to Regulate Trout R

Glen Canyon than Higher Fluctua

• ‘Juvenile Stranding Flow’: High steady flow for 2 day

decrease in flow to 5 kcfs for 24 hrs. 

•

One or two events in June and/or Ju

l

y when small YoY 

present in low angle shorelines where effects of flow chpronounced.

•

Will it Work?

–

Aug.-Sep. survival rate was anomalously low.

–

Hydro operations can strand fish (much literature and reg

• Stranding rates highest for very young/small fish and in low angle co

2003) such as cobble and vegetated sand bars in Glen Canyon.

• Stranding rates highest following a long habituation period t

o one flo

2003) like 10-18 kcfs summer flows.

• Juvenile stranding difficult t

o observe directly in field (Slatveit et al

evidence from fishing guides in Glen Canyon.

–

Will it have a significant effect on recruitment? Need to monitor 
Stranding Flow (con’t)

Reasons to Try It (assuming you want to reduce 

1) Reduce recruitment while minimizing impacts of foo

supporting adult growth and improving fishery.

2) If rainbow population in Marble Canyon is supporte

Glen Canyon, making Glen Canyon as attractive as pdensity with lots of food) may minimize emigration.

3) Less harmful than high fluctuations on sand storage 4) Stranding flow would be very easy and reasonably in

evaluate.

Reasons Not To:

1) Potential impact on native fish2) Not a moneymaker3) Need to maximize recruitment in Glen to meet mana
3) Did we find 

Young-of-Year downstream of Lee’s Ferry?

Yes, but very few. Spatial and seasonal patterns in YoY abundance suggest that the majority of them probably came from Glen Canyon.Growth rate and emergencetiming for YoY in MarbleCanyon identical to that fromGlen Canyon.

Backpack Electrof

0

50

100150200

Glen 0-15 15-

3

0 

Fish < 90 mm Per 100 m 

B

o

at Electrofis

0

50

100150200

Glen 0-15 15-30 

R

each in 15-

Mile 

Fish < 90 mm Per 100 m
Part IV: Reproduction of Rainbow Tro

Ferry

1) Is there substantial suitable spawning habi

mainstem?

2) Is there direct evidence of substantial spaw

mainstem? 

3) Is there suitable spawning habitat or direct 

spawning in tributaries downstream of Lee

4) Are there Young-of-Year downstream of L
2) Is there direct evidence of RBT s

the mainstem?

•

Coggins et al. found ripe fish during MR in winter but Co

saw no redds above minimum flow elevations (5 kcfs) basin spring.

–

They did not survey below minimum flow elevation

•

April ’04 trip found no redds above the minimum flow ele

–

Turbidity was too high to look for redds below minimum flo

•

June ’04 trip had good water clarity but no redds observed

–

Could have been too late in season.

•

Surveys were conducted following 9 mechanical removal 

possible that the majority of spawners were removed belo

–

However, removal would not have effected fish densities in 

Nankoweep Ck. where suitable spawning habitat is present.
Why VERY little Reproduction of 

Trout in Marble Canyon in 20

1) Mechanical removal removed all the spawners. Un

fish above and withi

n control reach. No reason spa

concentrated in removal reach (mostly below LCR

2) Spawning habitat in mainstem and tributaries too e

Nankoweep is suitable as are small areas in mainstnot be consistently available across years. Consistebe a requirement for substantive use if spawning si

3) Current condition of fish in Grand Canyon is too p

maturation due to lower food supply relative to Gledensities were lower, growth in Grand Canyon may 
Measuring Recruitment Factors usin

Catch-at-Age Modelling App

•

Define spawn-timing and magnitude throug

•

Measure change in length-frequencies from 

Catch-Per-Effort sampling in 2 habitat type

•

Length-stratified sub-sample of catch to me

age from daily otolith increments

•

Fit survival rate, hatch-timing, movement, a

vulnerability parameters of statistical catch-using maximum likelihood
Conflict Between 2004 Observation of 

with results from Tagging Studies (8

Documenting Limited Downstrea

0

50

100150200250300350

1988 1990 1992 199

4 

CPE (Fish/Hour)

Glen CanyonCPELCR InflowReach CPEGlen CanyonKn

0

50

100150200250

0 25 50 

Miles D

o

wn

CPE (Fish/Hour)

•

Increased densities in Glen 

through 90’s due to ROD flows could have increased rate of downstream dispersal.

•

Resulting high densities of 

trout in Marble Canyon led to reduced growth which could have reduced reproduction.