Update on 2003 and 20

Mechanical Removal oNative Fishes From the Colorado River

Southwest Biological Science CenterGrand Canyon Monitoring and Research Lew Coggins and Mike Yard

Preliminary Data Subject 
Objectives

 Efficacy of Mechanical Removal 

and BNT from the LCR Inflow Re

 To what extent can we remove non-

a large reach of the Colorado River?

 Rainbow and Brown Trout Diet A

Predation.

 What are non-native fish eating?

 Effect of Adult RBT and BNT on t

Dynamics of the LCR HBC Popul

 Will humpback chub recruitment in

of non-native removal?

Preliminary Data Subject 
Mechanical Removal Reach

Little CoReach (Chuar RLava ChR

eac

h, 

Preliminary Data Subject 
Mechanical Removal Reach 

N u m b e r o f D ep le tio n Pa s

0123456

Jan-03

Feb-03

Mar-03

Jul-03

Aug-03

Sep

Depletion Passes

N u m b e r o f D e p le tio n P as

R e m 

01234

Jan-03

Feb-03

Mar-03

Jul-03

Aug-03

Sep

Depletion Passes

Preliminary Data Subject 
Little Colorado River Removal Rea

Ele

ctrofi

shing Catch by Spe

cie

s and Month within t

h

e Little C

olorad

o 

0%

10

%

20

%

30

%

40

%

50

%

60

%

70

%

80

%

90

%

100%

Speckled Dace

7

2

8

6 18 53 34 92

4

7

Flannelm

outh Sucker 18

8 161 89 26

6

7

9 119 16

9 110 21

8

296 

Hu

mpback Chub 26 26 13 12

6 17

3

7

51 5

2

61 142

Bluehead Suck

er 8 18 11 12

4 19 32 37 24

8

4 

Unid

entifie

d Suck

er 2 0 0 3

5 430

3

0

F

athead Minnow 17

21 8

4

0

4 18 13 44

3

2

Co

m

m

on Carp 80 33 22

2

9 14 31

2

3

9 18

2

6 

Brown Trout 8

7

2

4

21 63 12 11 88 29 22

2

9

Rainbo

w Trout 3605 1900 1195

2

2

9

8 77

9

818 13

3

0

6

2

2

867 1464 

Jan-03

F

eb-0

3

M

ar-0

3 Jul-03

Aug-0

3

S

ep-0

3 Jan-0

4

F

eb-0

4

M

ar-04 Jul-0

4

Preliminary Data Subject 
Little Colorado River Removal Rea

El

e

ctrofishing Cat

ch R

ate f

or NonN

ativ

e Fish 

S

p

e

cies 

within t

he Little Col

orad

0

0.10.

2

0.

3

0.

4

0.

5

Jan-03

Feb0

3

M

ar-0

3 Jul-03

Aug-03

Sep0

3 Jan-0

4

Feb-04

M

ar-0

4 

RBT Catch/Minute

Preliminary Data Subject 
Little Colorado River Removal Rea

Electrofishing 

C

atch R

ate for

N

ative Fish Species within the Little C

olor

ado 

0

0.

01

0.

0

2

0.

0

3

0.

0

4

0.

0

5

0.

0

6

Jan-03

Feb-03

M

ar-0

3 Jul-03

Aug-0

3

Sep-0

3 Jan-04

F

e

b-04

Fish/Minute

Bluehead Sucker

Humpback Chub

Flannelmouth Sucker

Speckled Dace

Preliminary Data Subject 
Little Colorado River Rem

oval Reach Rainbow 

Rainbow Trout Abundance in the Little Colorado River Removal Reach

0

10002000300040005000600070008000

January03 - Initial

January03 - Final

February03 - Initial

February03 - Final

March03 - Initial

March03 - Final

July03 - Initial

July03 - Final

August03 - Initial

August03 - Final

September03 - Initial

September03 - Final

January04 - Initial

January04 - Final

February04 - Initial

February04 - Final

March04 - Initial

March04 - Final

July04 - Initial

Abundance

Proportion of January 2003 Rainbow Trout Abundance in the Little Colorado River Removal R

0%

10%20%30%40%50%60%70%80%90%

100%

January03 - Initial

January03 - Final

February03 - Initial

February03 - Final

March03 - Initial

March03 - Final

July03 - Initial

July03 - Final

August03 - Initial

August03 - Final

September03 - Initial

September03 - Final

January04 - Initial

January04 - Final

February04 - Initial

February04 - Final

March04 - Initial

March04 - Final

July04 - Initial

Proportion of January 03 Abundance

Preliminary Data Subject 
Little Colorado River Removal Reach Rainbow 

Efficacy

How fast they come in.... 773/mo How fast can w

out...12%/pass

Depletion Passes versu

012345678

Jan-03 Feb-03 Mar-03 Jul-03 Aug-0

Depletion Passes

Depletion PassesRemoval Efficiency

Monthly Rainbo

w Trout Im

migration Rate Into The LCR Removal Reach

773

-500

0

500

1000150020002500

Jan-Feb Feb-Mar Mar-July July-Aug Aug-Sep Sep-Jan Average

2003&2004

Estimation Interval

Fish/Month

20032004

Preliminary Data Subject 
Lava-Chuar to Tanner Removal Re

Electrofishi

n

g C

atch b

y S

pecies and M

o

nth within t

he Lava C

h

u

ar t

o T

0%

10%20%30%40%50%60%70%80%90%

100%

Speckled D

ace 3 5 

Flannelm

outh Sucker 1 15 1

4 25 6 11 

Humpback Chub 1 4 1 5 1 1 Bluehead Sucker 2 16 1 3 F

athead Minno

w 3 2

3 1 12 

Co

m

m

on Carp 7 15 5 6 3 12 

Brown Trout 3 9 18 17 6 5 Rainbow Trout 128 312 271 220 169 124 

Aug-03

Sep-03 Jan-04

Feb-04

Aug-04

Sep-04

Preliminary Data Subject 
Lava Chuar to Tanner Removal Reach Rainbo

Rainbow Trout Abundance in the Lava-Chuar to Tanner Remo

0

100200300400500600

January04 - Initial

January04 - Final

February04 - Initial

February04 - Final

August04 - Initial

AFil

Abundance

Preliminary Data Subject 
Rainbow Trout Diet

RAINBO

W T

R

O

U

T - 2

0

0

3

0%

10%20%30%40%50%60%70%80%90%

100%

JAN

FEB

MAR

JUL

AUG

SEP

JAN

FEB

MAR

A

B

O

VE L

C

R

B

DIET PROPORTION

AQ

U I

NVER

T

T

E

R I

NVER

T FI

S

H

O

THER V

E

R

T

RAINBO

W T

R

O

U

T : 2

0

0

3

0.000.050.100.150.200.250.300.350.400.450.50

JAN

FEB

MAR

JUL

AUG

SEP

JAN

FEB

MAR

A

B

OVE L

C

R BE

DIGESTIBLE CONTENTS ( g )

Preliminary Data Subject 
Rainbow Trout Diet

Preliminary Data Subject 

RAINBO

W T

R

O

U

T

AB

O

V

E L

C

R

0%

10

%

20

%

30

%

40

%

50

%

60

%

70

%

80

%

90

%

100%

JA

N

FEB

M

A

R JU

L AU

G

S

E

P

DIET PROPORTION

RAINBO

W T

R

O

U

T

B

ELO

W LC

R

0%

10

%

20

%

30

%

40

%

50

%

60

%

70

%

80

%

90

%

100%

JA

N

FEB

M

A

R JU

L AU

G

S

E

P

DIET PROPORTION
Brown Trout Diet

BROWN TROUT - 2003

0%

20%40%60%80%

100%

JAN

FEB

MAR

JUL

AUG

SEP

JAN

FEB

ABOVE LCR 

DIET PROPORTION

AQU INVERT TER INVERT FISH OTHER VERT

BROWN TROUT : 2003

0.000.100.200.300.400.500.600.700.800.901.00

JAN

FEB

MAR

JUL

AUG

SEP

JAN

FEB

MAR

ABOVE 

DIGESTIBLE CONTENTS( g)

Preliminary Data Subject 
Brown Trout Diet

Preliminary Data Subject 

BROWN TROUT 

ABOVE LCR

0%

10%20%30%40%50%60%70%80%90%

100%

JAN FEB MAR JUL AUG SEP

DIET PROPORTION

BROWN TROUT 

BELOW LCR

0%

10%20%30%40%50%60%70%80%90%

100%

JAN FEB MAR JUL AUG SEP

DIET PROPORTION
Predation Assessment Results: Ra

0.00

%

0.20

%

0.40

%

0.60

%

0.80

%

1.00

%

1.20

%

1.40

%

1.60

%

1.80

%

2.00

%

January February M

arch 

AB

R

ainbow Trout (>

2

5

0 m

m)

Me

a

n M

D

ate

L

ocati

o

n

xP N Pre

d % SEP CV TLPRED T

J

A

N

U

A

R

Y

Abo

v

e LC

R 18 217

7

0.8

3

%

0.094% 0.235

3

4

6

 Belo

w

L

C

R

9

510 1.76

%

0.338% 0.330

3

4

4

F

EBRU

ARY Ab

o

v

e L

C

R 16 112

0 1.4

3

%

0.178% 0.248

3

5

0

 Belo

w

L

C

R 1 205 0.98

%

0.579% 0.704

315 

M

A

R

C

H

Abo

v

e LC

R 1 637 0.16

%

0.157% 0.999

3

4

0 

 Belo

w

L

C

R 1 101 0.99

%

0.988% 0.995

4

7

0 

C

O

M

BIN

E

D Tot

al 46 475

0

0.9

7

%

0.055% 0.147

3

4

2

Ab

o

v

e L

C

R 35 393

4

0.8

9

%

0.062% 0.168

3

4

0

Belo

w L

C

R 11 81

6 1.35% 0.22

2

%

0.2

9

9 35

0

O

b

serv

ations

E

sti

m

ate

d P

ara

m

eters

Pred

ator C

har

a

cte
Predation Assessment Results: Br

0.00%

10.00%20.00%30.00%40.00%50.00%60.00%70.00%80.00%

January

February

March 

AB

Brown Trout (

>

2

5

0 m

m) O

b

serv

ations

Me

an 

D

ate Lo

c

ation

xP N Pre

d % SEP CV TLPRED 

JANUARY Ab

o

v

e L

C

R 1 49 2.04% 2.03

% 0.990 41

4

 Belo

w

L

C

R

4 22 18.18

% 6.11% 0.452 376 

F

EBRUARY Ab

o

v

e L

C

R 1 9 11.11% 10.79% 0.94

3

407 

 Belo

w

L

C

R

7 10 70.00% 12.04

% 0.207 43

4

MA

R

C

H

Abo

v

e L

C

R 0 6 0.00% - - - 

 Belo

w

L

C

R

3 9 33.3

3

% 13.21% 0.471 385 

CO

M

BIN

E

D

T

otal 16 105 15.24

% 1.83% 0.230 409 

A

bov

e LC

R 2 64

3.13% 1.84

% 0.696 426 

Belo

w L

C

R 14 41

3

4.15% 4.25

% 0.217 40

7

E

sti

m

ate

d P

ara

m

eters

Pre

d

ator Char
Hoopnet Sampling Reache

Little ColorHoopnet S

Tanner ReachUnkar HReach

Preliminary Data Subject 
Hoopnet Sampling Results

Humpback Chub Relative Abundance (Catch

0.000.050.100.150.200.25

Jan-03

Feb-03

Mar-03 Apr-03

May-03

Jun-03

Jul-03

Aug-03

Sep-03

Oct-03

Nov-03

Dec-03

Jan-04

Feb-04

Mar-04 Apr-04

Fish/Hour

LCR Inflow ReachTanner ReachUnkar Reach

Preliminary Data Subject 
Hoopnet Sampling Results

Humpback Chub Relative Abundance (Catch/Rate) in the L

0

0.05

0.1

0.15

0.2

0.25

Jun-98

Aug-98

Oct-98

Dec-98

Feb-99 Apr-99 Jun-99

Aug-99

Oct-99

Dec-99

Feb-00 Apr-00 Jun-00

Aug-00

Oct-00

Dec-00

Feb-01 Apr-01 Jun-01

Aug-01

Oct-01

Dec-01

Feb-02 Apr-02 Jun-02

Aug-02

Oct-02

Fish/hour

Yellow=JanuaryRed=June and JulyWhite = SeptemberBlue= All other months

Preliminary Data Subject 
Additional Work

• Continue development of abundance estimat

turbidity

• Construct Jolly-Seber abundance estimator in • Complete Diet and Predation sample process

analyses for 2004

Preliminary Data Subject 
2003-04 Preliminary Conclusions

•

Non-native Removal Efficacy

•

Reduction of non-native catch composition proportion from ~9

•

Conti

nued persistent reduction of RBT to b

etween 10% and 3

abundance.

•

Diet and Predation

•

RBT Dominant Prey item aquatic i

nvertebrates (Si

muli

ds, Blac

•

Temporal and spatial changes i

n R

BT diet

• Increased terrestrial component i

n summer

• Increased biomass consumed above the LCR

•

BNT dominant prey item variable (aquatic i

nvertebrates and fi

•

Temporal and spatial changes i

n BNT diet

• Increased terrestrial component i

n summer

• Less piscivorous above the LCR (li

kely related t

o native f

the LCR)

• Highly variable total biomass consumed rel

ated to compo

•

Predation assessment lab work still ongoing

•

Results for all of 2003-04 be presented at the October Sc

Preliminary Data Subject 
2003-04 Preliminary Conclusions

•

Effect of Non-Native Removal on H

Chub Population Dynamics

•

Relative abundance assessments (hoo

catch-rate) no substitute for stock assedetermine recruitment. Assessment of will require 2006 and 2007 monitoring 

•

Largest relative abundance of juvenile 

chub observed in last 6 years occurred Fall 04. Additionally, FMS and BHS dioverall positive trends in relative abund

•

However, these trends could be unrela

spuriously correlated with mechanical (increased temperature). Must contrasmechanical removal to find out.

Preliminary Data Subject 
Uncertainties and Recommendatio

•

At this point in time we do not have conclusive 

that mechanical removal efforts are providing atrends in HBC recruitment

•

Recommend con

tinuing mechanical r

emoval fo

additional year with ultimate length of this treatdetermined within the context of a blocked exp

•

We recommend discontinuing mechanical rem

context of a well designed experiment in order power of detecting a response of this treatmen

•

We recommend that the LTEP ad hoc conside

confounding in subsequent experimental plann

•

Examples of Confounding Factors: 

•

Unanticipated increase in water temperature ass

reservoir level

•

Variability in LCR juvenile HBC production

•

Variability in timing, magnitude, and duration of L

Preliminary Data Subject 
Results of Hoopnet

Sampling t

Changes in Juvenile HumpbacAbundance and Size Before an2004 Experimental High Flow

Lew

Coggins, GCMRC

Bill Persons, AGFDMike Yard, HSSRandy Van Haverbeke, USFWSJosh David, USFWS

Preliminary Data Subject 
Experimental Design

•

Hoopnet sampling to be conduc

three days before and after the experimental high flow.

•

Sampling locations and protoco

to those used during mechanicaoperation.

•

Dam releases constant 8000 cf

both sampling events.

Preliminary Data Subject 
Hoopnet Sampling Reache

Little ColorHoopnet S

Tanner ReachUnkar HReach

Preliminary Data Subject 
Hoopnet Sampling Results – C

Composition

Pre EHF Catches by LocationLocation HBC FMS BHS RBT BNT FHM CCF BBH LCR 208 4 3 3 0 3 0 Tanner 92 9 4 1 0 5 0 Unkar 12 15 2 3 3 0 0 Total Pre 312 28 9 7 3 8 0 Post EHF Catches by LocationLocation HBC FMS BHS RBT BNT FHM CCF BBH LCR 75 5 2 0 0 6 4 Tanner 26 1 2 0 0 3 1 Unkar 13 5 1 4 0 0 3 Total Post 114 11 5 4 0 9 8 Post/Pre FractionLocation HBC FMS BHS RBT BNT FHM CCF BBH LCR 36% 125% 67% 0% 200%Tanner 28% 11% 50% 0% 60%Unkar 108% 33% 50% 133% 0%Total Post 37% 39% 56% 57% 0% 113%

SpeciesSpeciesSpecies

Preliminary Data Subject 
Humpback Chub Relative Abundance (Catc

0

0.05

0.1

0.15

0.2

0.25

7/15/2004

7/20/2004

7/25/2004

7/30/2004

8/4/2004

8/9/2004

8/14/2004

8/19/2004

8/24/2004

8/29/2004

9/3/2004

9/8/2004

9/13/2004

9/18/2004

9/23/2004

9/28/2004

10/3/2004

10/8/2004

10/13/2004

10/18/2004

10/23/2004

10/28/2004

11/2/2004

11/7/2004

11/12/2004

11/17/2004

11/22/2004

11/27/2004

Catch/Rate (Fish/hour)

LCR Inflow ReachTanner ReachUnkar Reach

Hoopnet Sampling Results - A

Preliminary Data Subject 
Hoopnet Sampling Results – L

Frequency

Pre and post flood length frequency distribution of humpback chub at the LCR hoopnet sa

05

101520253035404550

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

Total length (mm)

Fish

Pre and post flood cumulative length frequency distribution of humpback chub at the LCR 

sampling site

0

0.10.20.30.40.50.60.70.80.9

1

30

50

70

90

110

130

150

170

190

210

230

250

270

290

310

330

350

Total length (mm)

Proportion offish

Pr

Preliminary Data Subject 
Hoopnet Sampling Results – T

Length Frequency

Pre and post flood length frequency distribution of humpback chub at the Tanner hoopnet s

02468

101214161820

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

Total length (mm)

Fish

Pre and post flood cumulative length frequency distribution of humpback chub at the Tann

sampling site

0

0.10.20.30.40.50.60.70.80.9

1

30

50

70

90

110

130

150

170

190

210

230

250

270

290

310

330

350

Total length (mm)

Proportion offish

Pr

Preliminary Data Subject 
Hoopnet Sampling Results – U

Length Frequency

Pre and post flood length frequency distribution of humpback chub at the Unkar hoopnet s

01234567

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

Total length (mm)

Fish

Pre and post flood cumulative length frequency distribution of humpback chub at the Unk

sampling site

0

0.10.20.30.40.50.60.70.80.9

1

30

50

70

90

110

130

150

170

190

210

230

250

270

290

310

330

350

Total length (mm)

Proportion of fish

Pr

Preliminary Data Subject 
Preliminary Conclusions 

 Relative Abundance of HBC decline

approximately 2/3 before and after tthe LCR and Tanner reaches. Relaabundance of HBC was unchanged reach before and after the EHF.

 Length frequency distribution of HB

and Tanner reaches was shifted to before and after the EHF suggesting in smaller fish following the EHF.

 Caveat: Concurrent with the EHF th

flooded. Therefore, sampling condinot identical before and after the EHturbidity in the Colorado River).

Preliminary Data Subject 
Preliminary Conclusions 

 Preliminary results suggest that the 

have been detrimental to juvenile Hin the LCR and Tanner Reaches

 Adaptive Management Practitioners 

cognizant of the potential detrimentaEHFs on juvenile HBC in the mainsColorado River.

 The EHF may make it more difficult 

determine the effect of mechanical the population dynamics of HBC unadequate long term experimental deadopted to disentangle the affects otypes of experimental actions.

Preliminary Data Subject 
Power Analysis for Estimating a Binomial Proportion

0

0.10.20.30.40.5

0 500 1000 1500 2000 

Sample Size

Coefficient of Variation ( SE(p^)/p^ )

Preliminary Data Subject