Chris Bare, Jim Latshaw, Ian Tattam, Jim Ruzycki, and Rich Carmichael

Estimating Chinook escapement to the John Day River basin using a mark-recapture approach

Presentation Outline

Monitoring adult spring Chinook

– Redd counts at index sites

– Redd counts at census sites

– Mark-recapture using PIT tag detections

2

3

John Day River Basin

OREGON

4

IndexCensus

Total survey = 268 km29% Index, 71% Census

Redd Surveys

520

0020

0220

0420

0620

0820

1020

1220

140

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

Jo

hn

Da

y E

sc

ap

em

en

t𝑹𝒆𝒅𝒅𝑻𝒐𝒕𝒂𝒍 ∙( 𝑭𝒊𝒔𝒉𝑹𝒆𝒅𝒅 )=𝑺𝒑𝒂𝒘𝒏𝒆𝒓𝒔

6

Concerns with Redd Counts– Index bias– Census assumptions – Detection probability

7

John Day Dam vs. Census Redd Counts

0 100,000 200,000 300,0000

500

1,000

1,500

2,000

2,500

John Day Dam Spring Chinook

Ce

ns

us

Re

dd

Co

un

ts

8

PIT-tagging Chinook in the John Day Basin

92000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000 South ForkNorth ForkMiddle ForkUpper MainstemLower Mainstem

PIT

-ta

gg

ed

Ch

ino

ok

PIT-tagged John Day Juvenile Chinook

10

Columbia River

Pac

ific

Oce

an

BON TDA

MJ1

Detection Site

Survey Reach

11

Estimating Abundance via Mark-Recapture

: estimated number of adult John Day Chinook at PIT tag array

Mark (M ): PIT-tagged adult John Day origin Chinook detected at array

Capture (C ): intact carcasses scanned for PIT tag on spawning grounds

Recapture (): fish in group M recovered on spawning grounds

12

- Closed population: 100% homing from detection arrays to spawning grounds

- Equal pre-spawn mortality among marked and unmarked fish

- Marks are retained during upstream migration

- Equal number of marked males and females

- Mark does not affect probability of detection

- Observers correctly record all marks

Mark-Recapture Assumptions

132009 2010 2011 2012 2013 2014

0

200

400

600

800

1,000

1,200

1,400

1,600MarkCaptureRecapture

Ch

ino

ok

Basinwide Marks, Captures, and Recaptures

665

24 9 1612

14

2009 2010 2011 2012 2013 20140

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000Mark-Recapture

Redd Expansion

Ch

ino

ok

Basinwide Abundance Estimates

152012 2013 2014

0

100

200

300

400

500

600MarkCaptureRecapture

Ch

ino

ok

Middle Fork Marks, Captures, and Recaptures

16

2012 2013 20140

500

1,000

1,500

2,000

2,500Mark-Recapture

Redd Expansion

Ch

ino

ok

Middle Fork Abundance Estimates

17

PIT-falls…

18

Basinwide Redd Expansion vs. Mark-Recapture Estimates

3,5004,0004,5005,0005,5006,0006,5007,0007,5002,000

4,000

6,000

8,000

10,000

12,000

Ma

rk-R

ec

ap

ture

Es

tim

ate R = 0.427

p = 0.399

19

900 1,100 1,300 1,500 1,700 1,900 2,100 2,3002,000

4,000

6,000

8,000

10,000

12,000

Census Redds

Ma

rk-R

ec

ap

ture

Es

tim

ate R = 0.792

p = 0.060

Basinwide Redd Counts vs. Mark-Recapture Estimates

20

Future Directions

• Genetic Stock Identification

• Better understanding of survival during adult life history

21

Acknowledgements

• Oregon Watershed Enhancement Board• Bonneville Power Administration• Confederated Tribes of the Warm Springs

Reservation• Private landowners• Field crew and volunteers

Chris Bare, Jim Latshaw, Ian Tattam, Jim Ruzycki, and Rich Carmichael

Estimating Chinook escapement to the John Day River basin using a mark-recapture approach