Is there evidence for stock segregation in Chinook salmon during ocean residence?

Indicators of survival: reconstruction of juvenile size-at-emigration Is bigger better?Who survives?

Jessica Miller, Oregon State University, Coastal Oregon Marine Experiment Station, Department of Fisheries & Wildlife

Biogeochemical tags - otoliths

Is there evidence for stock segregation during ocean residence?

Classification success (% correct)  

Stock Year of capture Year prior to capture Random

Central Valley (21) 67 71 48

Rogue River (10) 73 64 18

Mid-Columbia (11) 70 60 30

Average 69 67 36

Fre

quen

cy

Estimated fork length at initial emigration (mm)

1214

2012

3.53.7

Fre

quen

cy

Fork length at release (mm)

CROOS adults from Central Valley

Central Valley hatchery releases

Millions of fish

(50 fish)

(49 fish)

Reconstruct juvenile size-at-emigration Is bigger better?Who survives?

There is evidence for stock segregation during ocean residence

Central Valley, Rogue, and Mid-Columbia stocks

Variability in juvenile size-at-emigration

Relative importance of smaller migrants, natural-productionContribution of ‘fry’ migrants