Taku and Chilkat Rivers Chinook Salmon

Stock Assessment and Trends

Philip Richards: Alaska Department of Fish and Game, Division of Sport Fish, Juneau

Jeff Williams: Alaska Department of Fish and Game, Division of Sport Fish, Juneau

Brian Elliott, Alaska Department of Fish and Game, Division of Sport Fish, Haines

Territorial Sportsmen Hosted Event

March 27, 2019

1

• Drainage information

• Life history

• Stock assessment projects

– adult and juvenile “smolt”

• Results

- Spawning escapements

- Who, when, where and how many fish are harvested?

- Where are the big fish?

- Is it possible to increase run size?

- When will things get better?

Outline – Taku River Chinook Salmon

2

Taku River Description and History

• Remote, large-sized glacial river (17,000 km2, > Connecticut)

• Transboundary – originates in British Columbia

• > 90% of the Taku River watershed is in Canada

• ALL Chinook salmon spawn in Canada

• Standardized escapement estimates since 1973

• 25 years of full stock assessment – smolt/harvest/escapement

• Management and harvest are covered under the Pacific Salmon

Treaty and numerous domestic policies 3

• > 98% juveniles rear in freshwater for 1 year after hatching

• Smolt leave the system in May and June

• Rear in the Gulf of Alaska and Bering Sea for 1 to 5 years

• Adults return as mostly 5 and 6 year olds during April, May

and June

• BEG 19,000 – 36,000 large Chinook (McPherson et al. 2010)

• Average run size ~ 50,000 large seen prior to the recent poor

production, but since 2007 it has been ~ 30,000

• < 10,000 in 2017 and 2018 – lowest runs on record

Taku River Chinook Salmon Life History

4

Adult Stock AssessmentMark-Recapture Experiment = Inseason and Spawning Abundance

5Event 1 Event 2

• Standardized since early

1970s

• Peak counts are expanded

• 5 major spawning

tributaries– Nakina River

– Nahlin River

– Kowatua River

– Tatsamenie River

– Dudidontu River

• 20% of escapement

Adult Stock AssessmentAerial Surveys = Spawning Abundance

6

Event 1 - Smolt from brood year 2017

are leaving the Taku River in spring

2019

Event 2 - Chinook from this age class will be sampled for adipose fin clips

and coded wire tags during the next 4 return years

2020: 3 year old 2021: 4 year old 2022: 5 year old 2023: 6 year old

Brood Year

2017 samples

Smolt Stock AssessmentMark-Recapture Experiment = Smolt Abundance

Event 1 – Tagging Smolt

Seines & Minnow Traps

30,000 smolt tagged annually

Smolt Stock AssessmentMark-Recapture Experiment = Smolt Abundance

8

Smolt Stock AssessmentMark-Recapture Experiment = Smolt Abundance

9

Event 1 - Tagging Smolt

Coded Wire Tags

Coded Wire Tag

• 1.0 mm stainless steel wire

• Injected into snout

• Unique codes to identify release group (hatchery or wild stock)

•All tagged fish are adipose clipped

• 50 million coded wire tags release annually coastwide 10

11Event 2 – Sampling for Theta

Smolt Stock AssessmentMark-Recapture Experiment = Smolt Abundance

Use of Theta (Q)

QS: used to calculate smolt abundance based on 2-

event mark-recapture

n1, n2, m2

SW BW TP

or year Catch a a' t t' m theta Calc'd phi lambda 95% CI

Year Fishery District Time Q/D N Var[N] n2 a1 a2 m1 m2 mc pi (th) n1 (n2/N) G(pi) G(1/th) G(Ni) Var[n1i] SE[n1i] RP[n1i]

2006 Purse seine 112 SA 12 NE 715 0 600 84 83 76 76 2 0.003373 0.0780 31 84% 0.9881 0.468 0.010 0 453 21 69%

2006 age-1.1 recoveries total 2 31 21

2007 Drift gillnet 115 SW 27-37 NE 435 0 241 21 21 19 19 6 0.024896 0.0780 139 55% 1.0000 0.159 0.010 0 3,239 57 41%

2007 Troll 114 TP 4 NW 306 0 74 8 8 7 7 1 0.013514 0.0780 53 24% 1.0000 0.981 0.010 0 2,761 53 99%

2007 Troll 110 TP 5 NE 1,248 0 147 9 8 5 5 1 0.007653 0.0780 123 12% 0.8889 0.992 0.010 0 14,890 122 100%

2007 Haines sport 115-34 BW 10-13 NE 44 219 8 1 1 1 1 1 0.125000 0.0780 71 18% 1.0000 0.986 0.010 0.1131 4,916 70 99%

2007 age-1.2 recoveries total 9 385 161

2008 Drift gillnet 108 SW 24 NE 1,267 0 655 29 29 29 29 1 0.001527 0.0780 25 52% 1.0000 0.960 0.010 0 591 24 98%

2008 Drift gillnet 115 SW 25 NW 177 0 32 6 6 5 5 1 0.031250 0.0780 71 18% 1.0000 0.986 0.010 0 4,964 70 99%

2008 Troll 114 TP 2 NW 2,243 0 1,196 80 74 65 65 1 0.000904 0.0780 26 53% 0.9250 0.962 0.010 0 651 26 98%

2008 Troll 114 TP 3 NW 51,297 0 19,340 1,337 1,302 944 938 2 0.000107 0.0780 70 38% 0.9676 0.486 0.010 0 2,428 49 70%

2008 Juneau sport 111-50 BW 17 NE 482 8,578 123 6 6 6 6 1 0.008130 0.0780 50 26% 1.0000 0.980 0.010 0.0369 2,479 50 99%

2008 Haines sport 115-34 BW 9-12 NE 27 128 10 2 2 2 2 1 0.100000 0.0780 35 37% 1.0000 0.971 0.010 0.1756 1,171 34 99%

2008 Haines subs 115-32 BW 12-14 NE 28 0 13 1 1 1 1 1 0.076923 0.0780 28 46% 1.0000 0.964 0.010 0 736 27 98%

2008 age-1.3 recoveries total 8 305 114

2009 Troll 113, 114 TP 2 NW 15,888 0 7,910 522 519 373 373 7 0.000890 0.0780 181 50% 0.9943 0.137 0.010 0 4,801 69 38%

2009 Gustavus sport Area G 2009 NW 384 147,456 384 30 29 13 13 1 0.002694 0.0780 13 100% 0.9667 0.925 0.010 1.00 176 13 100%

2009 Haines sport 115-32 BW 9-12 NE 111 76 61 10 10 10 10 8 0.131148 0.0780 187 55% 1.0000 0.120 0.010 0.0062 4,664 68 37%

2009 Haines subs 115-32 BW 12-13 NE 46 0 11 2 2 2 2 1 0.090909 0.0780 54 24% 1.0000 0.981 0.010 0 2,825 53 99%

2009 age-1.4 recoveries total 17 435 112

Total 74,698 36 1,156 51,745 227 38.6%

Bernard and Clark 1996

( )( )( )( )( ) ( )21

11

2

2

2

222121

++

−−++=

mm

mnmnnnVar

QM: used to calculate marine harvest in mixed-stock

fisheries, includes valid-read tags from Taku River

Chinook

Results

• Spawning escapements

• Who, when, where and how many fish are harvested?

• Where are the big fish?

• Is it possible to increase run size?

• When will things get better?

13

14

Taku Escapement and Harvest – How Many

Low Harvest Rate

Average ~ 20%

2016-2018: with zero harvest would have still been below BEG

2016-2018: with zero harvest would have still been below BEG

Chilkat Escapement and Harvest – How Many

Total Harvest – How Many by Whom

16

Alaska Harvest – How Many by Whom

17

Alaska Harvest – When, Where and by Whom

18

Taku River Chinook Salmon Coded Wire Tag Recoveries

by Fishery and Subdistrict

Alaska harvest onlyRecent 10 year average

19

Harvest – When, Where and by Whom

20

Harvest – When, Where and by Whom

Taku “High Seas” Coded Wire Tag Recoveries, 1976 to 2017

n = 17

Where are the BIG FISH

21

Where are the BIG FISH

400

450

500

550

600

650

700

750

800

850

90019

8819

8919

9019

9119

9519

9619

9719

9819

9920

0020

0120

0220

0320

0420

0520

0620

0720

0820

0920

1020

1120

1220

1320

1420

1520

16

Len

gth

(M

M M

EF

)

Return year

Taku River Chinook Salmon Size at Age; 1988-2016 (n = 23,000)

2 Ocean

3 Ocean

4 ocean

22Run Year

4 Year old

5 Year old

6 Year old

Where are the BIG FISH

23

6 Year Olds

- Larger

- 70% female

0%

10%

20%

30%

40%

50%

60%19

76

19

77

19

78

19

79

19

80

19

81

19

82

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

Per

cen

tag

e o

f T

ota

l R

etu

rn

Brood Year

Taku Chinook Age at Return, 1976 to 2012

Can We Increase Run Size

• Two main ingredients in the recipe for Chinook production

24

Can We Increase Run Size

• Two main ingredients in the recipe for Chinook production

1. Smolt abundance (freshwater production)

25

Can We Increase Run Size

• Two main ingredients in the recipe for Chinook production

1. Smolt abundance (freshwater production) 2. Marine Survival (smolt to adult survival)

26

Will Increasing Escapement Increase Freshwater Production

27

Will Increasing Escapement Increase Freshwater Production

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

4,500,000

Esc

ap

emen

t (l

arg

e fi

sh)

Sm

olt

ab

un

da

nce

Brood Year

Taku River Chinook Salmon Smolt Abundance

Smolt abundance Escapement 28

Will Increasing Escapement Increase Freshwater Production

= NO

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

4,500,000

Esc

ap

emen

t (l

arg

e fi

sh)

Sm

olt

ab

un

da

nce

Brood Year

Taku River Chinook Salmon Smolt Abundance and Escapement

Smolt abundance Escapement 29

Why are Taku River Chinook Salmon Runs Poor

30

1,960,000

98% UNKNOWN morality due to natural

mortality, incidental mortality, un-identified

harvest

25,000 Escapement

15,000

Harvest

2% Marine Survival

1,980,000

98% UNKNOWN morality due to natural

mortality, incidental mortality, un-identified

harvest

20,000 Escapement

0

Harvest

Average Taku Chinook Smolt Production

2,000,000

1% Marine Survival

31

1,960,000

98% UNKNOWN morality due to natural

mortality, incidental mortality, un-identified

harvest

25,000 Escapement

15,000

Harvest

2% Marine Survival

1,980,000

98% UNKNOWN morality due to natural

mortality, incidental mortality, un-identified

harvest

20,000 Escapement

0

Harvest

Average Taku Chinook Smolt Production

2,000,000

1% Marine Survival

32

1,960,000

98% UNKNOWN (natural mortality,

incidental mortality, un-identified harvest)

25,000 Escapement

15,000

Harvest

2% Marine Survival

1,980,000

99% UNKNOWN (natural mortality,

incidental mortality, un-identified harvest)

20,000 Escapement

0

Harvest

Average Taku Chinook Smolt Production

2,000,000

1% Marine Survival

33

1,960,000

98% UNKNOWN (natural mortality,

incidental mortality, un-identified harvest)

25,000 Escapement

15,000

Harvest

2% Marine Survival

1,980,000

99% UNKNOWN (natural mortality,

incidental mortality, un-identified harvest)

20,000 Escapement

0

Harvest

Average Taku Chinook Smolt Production

2,000,000

1% Marine Survival

34

Escapement Goal

19,000 to 36,000

1,960,000

98% UNKNOWN (natural mortality,

incidental mortality, un-identified harvest)

25,000 Escapement

15,000

Harvest

2% Marine Survival

1,980,000

99% UNKNOWN (natural mortality,

incidental mortality, un-identified harvest)

20,000 Escapement

0

Harvest

Average Taku Chinook Smolt Production

2,000,000

1% Marine Survival

35

Escapement Goal

19,000 to 36,000

Why are Taku River Chinook Salmon Runs Poor

= Marine Survival!!

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

9.0%

10.0%

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

% m

ari

ne

surv

iva

l

Brood year

Taku River Chinook Salmon Marine Survival, Brood Years 1991 to 2012

36

Why are Taku River Chinook Salmon Runs Poor

= Marine Survival!!

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

9.0%

10.0%

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

% m

ari

ne

surv

iva

l

Brood year

Taku River Chinook Salmon Marine Survival, Brood Years 1991 to 2012

Average Marine Survival has dropped by

half since brood year 2001 (~ 2007 run)

37

Why are Chinook Salmon Runs Poor in Southeast Alaska

= Marine Survival!!

38

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

9.0%

10.0%

199

1

199

2

199

3

199

4

199

5

199

6

199

7

199

8

199

9

200

0

200

1

200

2

200

3

200

4

200

5

200

6

200

7

200

8

200

9

201

0

201

1

201

2

% m

ari

ne

surv

iva

l

Brood year

Taku River Chinook Salmon

Marine Survival

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

199

8

199

9

200

0

200

1

200

2

200

3

200

4

200

5

200

6

200

7

200

8

200

9

201

0

201

1

% m

ari

ne

surv

iva

lBrood year

Chilkat River Chinook Salmon

Marine Survival

Key Points – Taku River Chinook

• 25 years of full stock assessment data…some of the only

defensible wild stock Chinook salmon data on the west coast

• Taku Chinook are only in Southeast Alaska from April to early

July

• Smolt abundance stable - through brood year 2012

• Very low harvest rate ~ 20%

• Marine survival dropped by one half since brood year 2001

(~ 2007 calendar year run)

• Age at return is changing – fewer older fish

• Size at age stable39

• 2018 escapement – lowest run on record

• 2019 Taku outlook – 9,050 large fish – well below escapement,

inseason projection available in late May

• 2019 Chilkat outlook – 1,000 large fish – well below escapement

• Foreseeable future (1-2 years) looks grim for Southeast Alaska

Chinook production

• Runs will not improve until marine survival improves

• Possible double whammy from the combination of extremely

poor escapements with fewer females (reducing freshwater

production for brood years 2016, 2017 and 2018??) and poor

marine survival

When Will Things Get Better?

40

Acknowledgements• Paul Kissner – standardized surveys and early tagging in

Southeast Alaska

• Keith Pahlke – 20 years Southeast Alaska Chinook stock

assessment

• Scott McPherson – full stock assessment in Southeast Alaska

• Kathy Smikrud – maps

• Marine Harvest Studies – Anne Reynolds Manney, Mike

Jaenicke and Diana Tersteeg

• Funding – Federal Aid in Sport Fish Restoration, General Fund,

Sustainable Salmon Fund, Pacific Salmon Commission, Chinook

Salmon Research Initiative41

Acknowledgements

42

Dave Magnus

Red Weller

Meg Cartwright

Chiska Derr

Dave Dreyer

Amy Holm

Kurt Kondzela

Doug Hill

Dale

Brandenburger

Cliff Kemmerling

Ron Hulse

Steve Huffine

Roger Hayward

Tim Schantz

Nicole Zeiser

John Preus

Andy Piston

Tom Cappiello

Matt Fox

John Barton

Jason Leavitt

Chris S’gro

Christie Hendrich

Roger Wagner

Greg Vaughn

Anne Craine

Jason Wolle

Chris Stack

Kris Maledy

Peter Montesano

Grant Ness

Jim Foster

Tina Evert

Paul Overturf

Tim Schantz

Cliff Kemmerling

Schyler Winnen

Eric Raitanen

Brett Haitt

Matt McHaley

Shane Rear

Lyman Jim

Chris Brun

Lori Weller

Holly Carrol

Brad Baker

Nicole Zeiser

Greg Vaughn

Steve Eger

Don Curfew

Jayme Schricker

Chris S’gro

Roger Wagner

Kristin Lyle

Micah Sanguinetti

Rich Duncan

Stephanie

Warnement

Joey Hancock

Alex Blaine

Chris Stack

Steve Alicandri

Kris Larsen

Connor Fergusen

Alex Pennino

Michael Enders

Nathan Frost

Alanna Gottshall

Red Weller

Max Schoenfeld

Malika Brunette

Mackenzie Oliver

Stephen Warta

James Bryant

Lars Sorensen

Joseph Simonowicz

Kristin Neuneker

Jeff Williams

Reed Barber

Liam Cassidy

David Folletti

Elizabeth Segars

Dana Vanburgh

Gordie Woods

Amy Holm

Larry Derby

Andrew Smoker

Dale Brandenburger

Cliff Kemmerling

Andy Piston

Peter Branson

Ron Hulse

Shane Rear

Roger Hayward

Tim Schantz

Krista Kissner

Christie Hendrich

Jayme Schricker

Jason Leavitt

Greg Vaughn

Chris S’gro

John Barton

Roger Wagner

Kristin Lyle

Chris Stack

Rich Duncan

Kris Maledy

Michael Enders

Nathan Frost

Alanna Gottshall

Mac Oliver

Tyler Hagerman

Stephen Warta

Lars Sorensen

Joseph Simonowicz

Jacob Ross

James Bryant

Paul Kissner

Scott Mcpherson

Keith Pahlke

Red Weller

Amy Holm

Dennis Hubartt

Robert Marshall

Steve Elliot

Don House

Mary Urquhart

Rocky Holmes

John

Derhovanisian

Steve Hoffman

Ed Jones

Dan Reed

David Evans

Jody Goffinet

Vanessa Nowland

Brian Frenette

Judy Lum

Malika Brunette

Kelly Reppert

Mike Wood

Randy Petersen

Todd Johnson

Phil Richards

Nathan Frost

Questions??

43