Taku and Chilkat River Chinook Salmon Stock Assessmentseafa.org/wp-content/uploads/2017/04/Richards-Taku... · •98% juveniles rear in freshwater for 1 year after hatching • Smolt

Taku and Chilkat River Chinook Salmon

Stock Assessment

Philip Richards: Alaska Dept. of Fish and Game, Div. Sport fish, Juneau

Jeff Williams: Alaska Dept. of Fish and Game, Div. Sport fish, Juneau

Brian Elliott: Alaska Dept. of Fish and Game, Div. Sport fish, Haines

• Why are Chinook salmon returns poor in SEAK?

Big Questions

Since 2007 Chinook salmon in Alaska have experienced poor production

Runs of Chinook salmon across 22 stocks in Alaska


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

Big Questions

http://imagelib.dfg.alaska.local/main.php?g2_itemId=3268&g2_imageViewsIndex=2



• Where are the big fish?

Big Questions




• Is it possible to increase run size?

Big Questions

Reduce harvest? Will increasing run size increase production?





• When will things get better?

Big Questions

• Southeast Alaska Chinook Salmon

• Chinook salmon harvest and management in Southeast Alaska

• Taku River – methods and trends nearly identical on Chilkat

• Drainage information and stock assessment history

• Stock assessment methods – adult and juvenile “smolt”

• Results – escapement, harvest, smolt abundance, and marine

survival

Results – will answer some of the “big questions”

Outline

• 34 Chinook salmon systems in Southeast Alaska

• 11 indicator stocks (>90% of wild production)

• ~100,000 wild “large” Chinook/year

• Large fish (≥660 mm MEF or 28”) - mostly 3 and 4 ocean, ♀

• Biological escapement goals for all 11 indicator stocks

• Taku and Stikine rivers >80% wild production (Chilkat 4%)

• Stock specific marine rearing patterns: inside and outside rearing

• Extensive SEAK hatchery program ~ 100,000 large Chinook/year

Southeast Alaska Chinook Salmon

Southeast Alaska Harvest and

Management

• Southeast Alaska harvests > 300,000 large Chinook/year – 80% commercial and 20% sport (all marine harvest)

• 70% from OR, WA, and B.C.

• Pacific Salmon Treaty – Account for all Chinook salmon harvest in SEAK

– Marine sampling programs in SEAK (harvest, biological information)

– Estimate escapements in SEAK (indicator stocks)

– Stock assessment programs in SEAK (escapement, smolt production,

harvest)

11 Southeast Alaska Indicator Stocks

Taku River Description and History

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

• Transboundary – originates in B.C.

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

• ALL Chinook salmon spawn in Canada

• Standardized escapement estimates since 1973

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

• > 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 3 ocean and 4 ocean during April, May

and June

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

• Average run size = 40,000 large

Taku River Chinook Salmon Life History

Taku River Chinook Salmon Life History Spawning Distribution

Full Stock Assessment Estimates

Full Stock Assessment Estimates

• Spawning escapement – age, sex, length

• Smolt abundance – how many smolt leave the system/annually

• Harvest – how many fish are caught

• Marine distribution – when, where and how fish are caught

• Total return by age = escapement + harvest

• Marine survival – smolt to adult survival rates

How do we get this information?

Adult Stock Assessment Mark-Recapture Experiment = Inseason and Spawning Abundance

Adult Stock Assessment Mark-Recapture Experiment = Inseason and Spawning Abundance

• 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 Assessment Aerial Surveys = Spawning Abundance

• Seines & Minnow Traps

30,000 smolt tagged annually

Smolt Stock Assessment Mark-Recapture Experiment = Smolt Abundance

Smolt Stock Assessment 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

Coded Wire Tag History

• Coast wide ocean sampling and recovery programs in AK,

B.C., WA, OR, and CA – in place for the past 40 years

• More than 50 million coded wire tags released annually

• Primarily used in hatcheries – some wild stocks tagged

• Stock identification tool used coastwide by PSC to estimate

stock composition

• GSI (genetics) is also used to estimate stock composition

- Summer 2014

- Winter 2015

- Spring 2016

Available Now!

Chinook News

www. adfg.alaska.gov

Sources for More Information

Results!!

Results!! Brood Year

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Spawning

Escapement Age

.3-.5 55,889 66,125 48,368 35,162 81,416 114,828 30,645 15,117 33,969 46,289 54,249 35,856 71,022 37,076 41,603 14,533

Female Spawners 32,954 36,149 16,815 14,100 38,122 44,247 13,919 9,838 15,798 23,434 23,486 17,346 37,560 19,198 20,790 8,564

Smolt Tagged 9,878 11,137 21,617 37,949 32,838 19,557 17,337 41,856 37,795 28,068 23,078 27,341 36,740 9,853 24,067 16,111

Smolt Abundance 1,972,159 1,113,799 1,435,853 1,244,759 1,923,761 1,926,211 1,196,952 1,739,455 1,985,002 2,133,384 1,586,446 1,586,568 4,020,066 2,030,960 3,234,738 1,329,776

SE 439,459 391,691 251,727 121,795 191,402 302,708 145,989 124,384 189,795 363,244 287,349 196,378 707,101 452,597 702,955 237,163

CV 22.3% 35.2% 17.5% 9.8% 9.9% 15.7% 12.2% 7.2% 9.6% 17.0% 18.1% 12.4% 17.6% 22.3% 21.7% 17.8%

Marked Fraction 0.5% 1.0% 1.5% 3.0% 1.7% 1.0% 1.4% 2.4% 1.9% 1.3% 1.5% 1.7% 0.9% 0.5% 0.7% 1.2%

Smolt per

Spawner 35 17 30 35 24 17 39 115 58 46 29 44 57 55 78 92

Total Return 82,442 20,133 36,004 53,774 79,543 62,980 52,180 105,826 112,104 50,966 24,572 51,092 51,460 47,333 46,107 43,202

Total Return age

.3 - .5 73,686 17,252 26,971 40,946 67,744 56,664 43,779 86,309 84,428 40,312 19,679 42,450 37,496 34,613 36,908 27,679

Marine Harvest 7,631 4,406 5,096 5,808 8,695 8,021 5,621 15,467 26,877 13,464 7,235 10,920 12,680 3,782 4,662 5,837

SE

CV 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%

Marine

Exploitation 9% 22% 14% 11% 11% 13% 11% 15% 24% 26% 29% 21% 25% 8% 10% 14%

Return per

spawner (all ages) 1.5 0.3 0.7 1.5 1.0 0.5 1.7 7.0 3.3 1.1 0.5 1.4 0.7 1.3 1.1 3.0

Return per female

spawner (all ages) 2.5 0.6 2.1 3.8 2.1 1.4 3.7 10.8 7.1 2.2 1.0 2.9 1.4 2.5 2.2 5.0

Marine Survival

(all ages) 4.2% 1.8% 2.5% 4.3% 4.1% 3.3% 4.4% 6.1% 5.6% 2.4% 1.5% 3.2% 1.3% 2.3% 1.4% 3.2%

Retrun per

spawner age .3-.5 1.3 0.3 0.6 1.2 0.8 0.5 1.4 5.7 2.5 0.9 0.4 1.2 0.5 0.9 0.9 1.9

Return per female

spawner age .3-.5 2.2 0.5 1.6 2.9 1.8 1.3 3.1 8.8 5.3 1.7 0.8 2.4 1.0 1.8 1.8 3.2

Marine survival

smolt to age .3-.5 3.7% 1.5% 1.9% 3.3% 3.5% 2.9% 3.7% 5.0% 4.3% 1.9% 1.2% 2.7% 0.9% 1.7% 1.1% 2.1%

1 -1)+(R

1)+1)(C+M( = NLR

ˆˆ

Chinook Salmon Life History 101

Brood Year vs Return year

• Brood Year

• Spawn in 2010

• Hatch spring 2011

• Smolt spring 2012

• 1 ocean (2013 return year)





• Return Year

• 2017 return year

• 1 ocean (2014 brood year)





Results





• When will things get better?

Why are Chinook Returns Poor in SEAK?

Harvest – Who and How Many

Avg. Harvest

Canada = 2,250

U.S. = 4,040

Total = 6,290

Avg. U.S. Harvest

Troll = 2,700

Sport = 760

Gillnet = 550

PU = 30

Total = 4,040

Harvest – Who and How Many

Harvest – Who, When and Where

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Taku River Chinook Salmon Salmon Coded Wire Tag Recoveries in Marine Fisheries of Southeast Alaska (1976-2016; n = 752)



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Taku River Chinook Salmon Salmon Coded Wire Tag Recoveries in Marine Fisheries of Southeast Alaska (1976-2016; n = 752)

Harvest – SEAK Chinook


Can We Increase Run Size?

• Two main ingredients in the recipe for Chinook production



1. Smolt abundance (freshwater production)



1. Smolt abundance (freshwater production)

2. Marine Survival (smolt to adult survival)




Why are Chinook Returns Poor in SEAK = Marine Survival

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Total Return vs Marine Survival - Strong Relationship!!

Total return Marine survival



Where are the BIG FISH


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

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Taku Chinook Salmon Harvest - Sport

• Based on the past 10 years of data using genetic stock

identification – considered very robust estimates of harvest

• 10% of the ANNUAL Chinook salmon harvested in the Juneau

area are from the Taku River (range 3% to 19%)

• Taku Chinook salmon are only present in the Juneau area from

late April – June

• 40% of the Chinook salmon harvested in the Juneau area from

late April – June are from the Taku River (range 12% to 65%)

• There is a strong relationship between the Taku River terminal

run and sport harvest

When Will Things Get Better?

(R2 = .80)

• 2017 Forecasts

• Taku = 13,300 terminal run (95% C.I. 9,700 – 22,800)

- Escapement goal = 19,000 – 36,000

• Chilkat = 1,037 large total run (95% C.I 681 – 1,393)

• Chilkat inriver = 634

- Escapement goal = 1,750 – 3,500

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

production

When Will Things Get Better?

Key Points – Taku River Chinook

• 24 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 SEAK from April-June

• Smolt abundance stable

• Very low harvest rate – 10% to 15%

• Marine survival dropped by one half since BY2001 (2007 return

year)

• Maturation rates are changing – fewer older fish

• Size at age stable

Key Points – Taku River Chinook

• Current marine conditions are poor for Southeast Alaska

Chinook salmon and throughout northern B.C. and Alaska

• Returns will not increase until marine survival improves

Acknowledgements

• Paul Kissner – standardized surveys and early tagging in SEAK

• Scott McPherson – full stock assessment in SEAK

• Kathy Smikrud – maps

• Funding – Federal Aid in Sport Fish Restoration, Sustainable

Salmon Fund, PSC, CSRI

• Staff

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

Micah Sanguinetti

Anne Craine

Alex Blaine

Jason Wolle

Chris Stack

Kris Maledy

Grant Ness

Jim Foster

Tina Evert

Paul Overturf

Tim Schantz

Cliff Kemmerling

Schyler Winnen

Eric Raitanen

Brett Haitt

Matt McHaley

Shane Rear

Christie Hendrich

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

Kris Maledy

Max Schoenfeld

Dave Dreyer

Malika Brunette

Dale Brandenburger

Gordie Woods

Amy Holm

Larry Derby

Andrew Smoker

Dave Magnus

Red Weller

Dale Brandenburger

Dave Dreyer

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

Micah Sanguinetti

Rich Duncan

Kris Maledy

Steve Alicandri

Michael Enders

Nathan Frost

Alanna Gottshall

Mac Oliver

Tyler Hagerman

Stephen Warta

Project Leaders,

Biometrician and

Staff

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

Malika Brunette

Kris Maledy

Micah Sanguinetti

Kelly Piazza

Mike Wood

Todd Johnson

Jeff Nichols

Brian Elliott

Troy Jaecks

Mackenzie Olvier

Alanna Gottshall

Michael Enders

Stephanie

Sanguinetti

Malika Brunette

Steve Alicandri

Acknowledgements

57

Questions??

58

Documents

Taku and Chilkat River Chinook Salmon Stock Assessmentseafa.org/wp-content/uploads/2017/04/Richards-Taku... · •98% juveniles rear in freshwater for 1 year after hatching • Smolt