Effects of 2003/2004 GCD Enhanced Fluctu

Flows on the Early Life History Stages 

Rainbow Trout in Glen Canyon

Josh Korman, Matt Kaplinski

Jeff Sneep, Steven Hall, 

Joe Hazel, Ted Melis

Funded from FY03/04 GCDAMP Experimental Flow Program
Objectives of Project

I. Estimate extent of mortality of eggs and alevins cause

Jan.-Mar. fluctuations and to predict effects of other fregimes.

II. Quantify spawning habitat preference (depth, velocity

substrate) to determine how discharge controls spawnelevation.

III. Estimate timing of emergence, growth, and mortality 

Young-of-Year (YOY) rainbow trout in their first six 

– as a monitoring tool to assess impacts from GCD operations t

multi-year comparisons under different flow regimes

– To improve understanding of mechanisms that control growth 

survival of fish that are likely most vulnerable to dam operatioinfo can in turn help design more effective flow regimes to rerecruitment

IV. Determine the origin of rainbow trout between Lee’s 

the LCR confluence

Part I: Factors That Determine Egg and A

Mortality Resulting from Fluctuating 

1) Timing of spawning and duration of incubation relative to c

flow regimes determine the fraction of eggs/alevins potentiaeffected.

2) Hypsometry (elevation of redds) determines the proportion 

egg/alevins that will be exposed for different durations.

3) Intergravel temperatures, controlled by the interaction of ele

and discharge, determine the extent of mortality

• Field data on each of these components collected in 2003 an

Spreadsheet model integrates results to compute relative mo
Egg and Alevin Mortality: Methods

• Redd surveys conducted at intensive sites and system-wide (R

determine magnitude and timing of redd deposition

– 1 survey/month Feb.-May 2003 (n=4) + lot’s of habitat data (fo– 2 surveys/month Feb-May 2004 + 1 survey/month Nov.-Jan. & 

• Counted redds and determined elevation at:

– 3 intensive sites (Four Mile, Powerline, and Pumphouse Bars) u

station and site-specific stage-discharge curves to get elevation 

– 24 other sites in Glen Canyon using a rod and level for clusters 

• Collected habitat information (depth, velocity, grain size) at i

sites in 2003 to determine spawing habitat preference.

• Measured intergravel temperatures at 4-5 elevations from 5 – 

two intensive sites (Four Mile and Powerline).

• Excavated 125 redds in 2004 to directly evaluate (roughly) ef

timing and elevation on egg mortality.
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Site Type

# Intensive# RAT

1000 0 100

Location of Spawning Areas

in Glen Canyon

From Kondolf, 2000
Redd Counts

2004

0

200400600800

10001200

Nov-23

Dec-23

Jan-21

Feb-04

Feb-29

Mar-14

Mar-28

Apr-18

May-02

May-22

# of Redds Present RAT FM, PL, PH

2003

0

200400600800

10001200

Feb-10

Mar-10

Apr-10

May-25

# of Redds Present
2004

0

200400600800

10001200

Dec-01

Dec-31

Jan-30

Feb-29

Mar-30

Apr-29

Redds Counted (/survey 

0

1000200030004000

Dec-01

Dec-31

Jan-30

Feb-29

Mar-30

Apr-29

Total Redds

20042003

2003

0

200400600800

10001200

Dec-01

Dec-31

Jan-30

Feb-29

Mar-30

Apr-29

Redds Counted (/survey

Total redds for year and timing of excavation estimated from raw counts and survey life

•E=AUC/SL•Estimate survey life (SL) from GIS (= 3.3 – 4.2 wks) at intensive sites•Estimate total redds (E) and timing of spawning from raw counts
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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Elevation (k

# 12-15# 15-20# 5-8# 8-12# <=5

System-Wide Redd Hypsometry

Intensive + RAT (2004)

397 443 681 962 439 271 136

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

Intensive + RAT (2003)

757 936 878

0

20406080

100

Mar-10

Apr-10

May-25

% of Redds
Intergravel Temperature

Four Mile Bar (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)

510121517.5Lethal Limit

Powerline Bar (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 Limit

Four Mile Bar (200

5

10152025303540

Feb-01 Feb-16 Mar-03 Mar-18 Apr-02 Ap

Max. Daily Temperature (C)

Powerline Bar (200

5

10152025303540

Feb-01 Feb-16 Mar-03 Mar-18 Apr-02 Ap

Max. Daily Temperature (C)
Temporal 

Dynamics of Mortality

2004

05

101520253035

Dec-01 Dec-31 Jan-30 Feb-29 Mar-30 Apr-29 

Redds (#/day)

Redds ExcRedds Sur

2003

05

10152025303540

Dec-01 Dec-31 Jan-30 Feb-29 Mar-30 Apr-29 

Redds (#/day)
Summary of Egg/Alevin Mortality

% Lost 23

0

0 79 68 

Total 4033 1811 1019 716 365 2003

% Lost 28

0

0 85 86 

Total 2142 1069 374 401 234 2004

1

12-15 

kcfs

8-12 

kcfs

All < 5 kcfs 5-8 kcfs

Stages
Direct Estimates of Egg Mortality

Feb-Mar A

Redds Examined 

<8 27 

8-12 46 

12-20 32 

Total 105 

Redds with Eggs (Live or 

<8 15 

8-12 33 

12-20 23 

Total 71 

% Redds with Dead Eggs 

<8 13 

8-12 24 

12-20 30 

Total 24 
Conclusions from Egg/Alevin Mortality St

• Increased fluctuations during Jan. likely do not cause much m

as emergence occurs before the onset of lethal temperatures.

• Extending the range of fluctuations through April or May thro

spawning period would substantially increase mortality.

• Decreasing the minimum daytime flow to 5 kcfs would substa

increase mortality by eliminating production from the 5-8 kcfs 

• Ultimate test of model will be to compare seasonal pattern in s

redd numbers with those inferred from back-calculated hatch dderived from fry sampling. Ideally this comparison would be dboth ROD- and enhanced fluctuation-years.
Part III: YoY Emergence Timing, Habit

Growth, and Survival

• Knowing emergence timing defines the window for flows tar

reducing YoY survival. In conjunction with redd counts can b

evaluate effects of flows on egg/alevin survival.

• Understanding ontogenetic habitat shifts from low angle shor

steeper habitats also useful for defining window of vulnerabil

• The effect of temperature and GCD operations on YoY grow

an important component that determines year-class strength.

• Documenting changes in the survival rate of YoY in first six 

when they are likely most sensitive to habitat changes would 

resolution monitoring tool to assess impacts of GCD operatio
Methods for YoY Study

• Monthly catch-per-effort sampling by backpack and boat electrof

fry habitat at daily minimum flow (23:00 – 7:00). 

• 2003 (Jun-Oct): 20 low angle backpack sites (LF only) • 2004 (Apr-Oct): 20 low angle backpack sites (LF)

20 steep talus shoreline boat sites (LF)80 sites from LF to LCR in Apr., Jun., an

• Age a subset of fish from otoliths to develop length-age key and 

estimate time of hatch and emergence. (n = 237 in 2003, 2004 pe

• Translate length-frequency of catch (by month) into age-frequenc• Use model to compute in-season estimates of apparent mortality 

recruitment.

• Examine relationships between operations and mortality and grow

patterns.
Habitat Types

Talus – Stee40% of Glen 30% of MarbSample by bo

Debris Fans, Sand Bars – L50% of Glen C50% of MarblSample by bacAnd boat/back
2004 Length Frequency

All Habitat Types

0

20406080

100120

20 30 40 50 60 70 80 9

Forklength (mm)

# Per 1000 m

AprMay JunJuly AugSep

Recruitment (emergence)Size-dependent VulnerabilitySurvivalGrowth

Factors Determining 

Changes in LengthFrequency Over Time

N = 4,300
2004 Length-Frequency in Glen Canyo

Steep Angle - Boat

0

20406080

100120140

20 30 40 50 60 70 80 90 10

Forklength (mm)

# Per 1000 m

Low Angle - Backpack

0

100200300400500600

20 30 40 50 60 70 80 90 10

Forklength (mm)

# Per 1000 m

April - 02May - 05June - 10July - 01August - 08September - 

Recruitment (emergence)Size-dependent VulnerabilitySurvivalGrowthMigration

Factors Determining 

Changes in LengthFrequency Over Time
Otolith Microstructure
Size-at-Age for YoY’s in Glen Canyon 2

0

20406080

100

0 50 100 150 200 25

Age (days from Hatch)

Forklength (mm)

Oct SeptJuly JuneMay April Best-fit von B
Back-calculated Timing of Hatch 20

0

20406080

100120140

1-Jan

31-Jan

2-Mar

1-Apr

1-May

31-May

30-Jun

30-Jul

29-Aug

Date of Hatch

# of Fish

0

20406080

100120

01-Jan

31-Jan

02-Mar

01-Apr

01-May

31-May

30-Jun

30-Jul

29-Aug

Date of Spawn

# of Hatched Eggs

050100150200250

# of Redds Excavated

Back-calculated from YoYRedds 2003
What Happened to YoY in Early Septemb

Weekly Recruitment - Cons

0

20406080

100

20 30 40 50 60 

Catch

PPOO

Weekly Recruitment - Mont

0

20406080

100

20 30 40 50 60 

Forklength (m

Catch

Flow-change induced movement 

out of low angle habitats

Flow-change induced mortality 

in low angle habitats

05

10152025

1-Nov

1-Dec

31-Dec

30-Jan

1-Mar

31-Mar

30-Apr

30-May

29-Jun

29-Jul

28-Aug

27-Sep

27-Oct

Discharge (kcfs)
And the Lord Clayton Said:

“Let them Grow on $unday”

8

101214161820

Jun-12

12:00

Jun-13

00:00

Jun-13

12:00

Jun-14

00:00

Jun-14

12:00

Jun-15

00:00

Jun-15

12:00

Jun-16

00:00

Jun-16

12:00

Jun-17

00:00

Jun-17

12:00

Discharge (kcfs)

20032004

Friday Saturday Sunday
Evidence that YoY do not follow the water

with flow increases during the day

July - 12 Sites

0

20406080

100120140

High Flow Low Flow High Flow Low Flow

Backpack (Cobble/Sand) Boat (Talus)

Fish/100 m

DayNight
Evidence That Suggests ‘Stranding’ Flows C

be Used to Regulated YoY Recruitment in 

Canyon

• Much literature on stranding:

– Stranding rates highest for very young/small fish and in low angle complex habitats (H

2003).

– Stranding rates highest following a long habituation period to one flow regime (Hallera

– Stranding difficult to observe directly in field (Slatveit et al. 2003).

• Daily fluctuations are likely reducing YoY growth but not daily s

events.

– Observed large decrease in catch rates during and after memorial day weekend.– 4-fold higher densities at low flow than at high flow (2004 study).– Literature

• Juvenile trout do not fully compensate for increased water flow by changing microposition (Ve• After initial velocity increases fish move closer to the streambed, and then, if necessary by mov

1994). 

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

holding (however this could be a temperature effect)

• Decreased density of fish in low angle habitats following Sept. change in 

flow

– Could have been a stranding-induced mortality or a temporary movement from low ang
Advantages of Stranding Flows

• High steady flow for 2 days followed by sudden decrease in flow to 5 kcf

Before and after monitoring to measure effect.

• One or two events in June and/or July when small YoY are most abundan

• Six Reasons to Try It Experimentally

1) Reduce recruitment while minimizing impacts of food base, thereby supportin

growth and improving fishery.

2) If rainbow in Marble Canyon are coming from Glen Canyon, making Glen as 

possible (low density with lots of food) may minimize emigration.

3) Smaller fluctuations will reduce downstream sand transport. We may be minin

resource when we don’t have to.

4) Potential impacts of fluctuating flows on native fish are reduced.5) Stranding flow would be very easy and reasonably inexpensive to evaluate.

• Conclusions depend in part on results from catch-at-age analysis on 2004 

to determine the extent of mortality from Sept. event.
1) Is there suitable spawning habitat in the mainstem?

2) Is there direct evidence of spawning in the mainste3) Are there Young-of-Year downstream of Lee’s Fer4) Is there suitable spawning habitat or direct evidenc

spawning in tributaries downstream of Lee’s Ferry

Part IV: Origin of Rainbow Trout below Lee
1) Is there suitable spawning habitat in 

mainstem?

0

0.10.20.30.40.5

0 0.25 0.5 0.75 1 1.25 1

Velocity (m/sec)

Utilization

FFP

0

0.10.20.30.40.5

0 15 30 45 

D85 (mm)

Utilization

Site

Area ('000 

m2) Grain Size D/V

FM 28 196 460

FS 17 136 177PL 11 64 257

PH <1 22 66

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1) Is there suitable habitat in the mainst

(con’t)

• Very small pockets of suitable gravel above 8 kcfs.• Small amounts of suitable spawning substrate below 8 kcfs ex

– 1.6*, 5.5, 37.6, 49.1, Little Nankoweep Ck., 53.1 (lower Nankowe

55.3*

• A good proportion of the suitable gravel we did find was 3-10 

and often below riffle/rapid where energy was high enough to 

but not too high to scour gravel. 

2) Is there direct evidence of RBT spawni

the mainstem?

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

saw no redds above minimum flow elevations (5 kcfs) based on limin spring.

– They did not survey below minimum flow elevation

• April ’04 trip found no redds above the minimum flow elevation (8 

– Turbidity was too high to look for redds below minimum flow.

• 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 trips in 1.5 

possible that the majority of spawners were removed below Kwagun

– However, removal would not have effected fish densities in the vicinity 

Nankoweep Ck. where suitable spawning habitat is present.
3) Did we find 

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

Boat Electrofishing

0

20406080

100

Glen 0-15 15-30 30-45 45-60 

Fish < 90 mm Per 100 m April June August

Backpack Electrofishing

0

1020304050

Glen 0-15 15-30 30-45 45-60 

Reach in 15-Mile Increments

Fish < 90 mm Per 100 m

Yes, but very few. Spatial and seasonal patterns inYoY abundance suggest that the majority of them probably came from Glen Canyon.
4) Is there suitable spawning habitat or dire

evidence of spawning in tributaries downstr

of Lee’s Ferry?

• In it’s April ’04 condition, Nankoweep Ck. could support a fe

thousand spawners.

– Gravel quality is excellent and temperature is suitable in winter– Emergence would need to occur by mid-March, thus spawning 

most of January would likely be successful.

• Saw a few pairs of fish spawning, but temperatures by April w

already too high.

• No YoY captured but they might have entered mainstem shor

emergence in March (but almost no mainstem YoY were foun

05

1015202530

0-Jan 20-Jan 9-Feb 29-Feb 20-Mar 9-Apr 29-Apr

Water Temperature (C)

Daily Avg.Daily Max.

Source: GCMRC DIWQP

All evidence suggests that there was very little rainbow trout repr

below Lee’s Ferry in 2004. Why?

1) Mechanical removal removed all the spawners. Unlikely, m

adult fish above and within control reach.

2) Spawning habitat in mainstem and tributaries to ephemeral. 

Nankoweep is suitable as are small areas in mainstem, but tnot have been consistently available across years, which marequirement for spawners to key-in on those locations.

3) Current condition of fish in Grand Canyon is too poor to su

maturation due to lower food supply relative to Glen Canyo

densities were lower growth in Grand Canyon may have besufficient.

Conclusions on Origin of Rainbow Trout b

Lee’s Ferry
Monitoring Options

A. Consistent and relatively long-duration treatments coupled 

monitoring adult abundance, size, and condition.

• Measuring what you care about• Time delays between treatment and response• Linkage to dam operations may be weak (depends on expt. D

B. Enhance A) with monitoring of growth and mortality for li

that are most sensitive to dam operations.

• Short response time• Strong linkage to dam operations• Does not require as rigorous an experimental design